Precor 9.21 Treadmill - Answered Questions & Fixed issues

You probably have a circut board malfunction.

https://www.precor.com/sites/default/files/manuals/Owners-Manual-164_920920s_19940901_ENGLISH.pdf http://www.buyfitnessonline.com/product_info.php?products_id=1015 Lisa if you go on the internet and type in people that service Precor products I am sure you'll find several of them here's a manual that might be some help.

it is there as a safety measure to stop you injuring your self Don't bypass it ---fix it and be safe

There is a red magnet or insert that it used as a safety key. If you lost it, you will need to buy another. Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/russell_1d1c35fa8a5a0be4

Adjusting Tension on a Treadmill Running Belt It is necessary to properly tension a treadmill belt when it is replaced. After time, a belt can stretch and may begin to slip. When this happens, it is necessary to adjust the tension of the running belt to stop it from slipping. Manufacturers of treadmills generally agree on one of three procedures for how to tension a treadmill running belt.

1. Adjust for no slippage of the treadmill walking belt on the front roller (Often referred to as the "Stomp Test")
   1. This procedure works well for a previously installed belt that is now slipping.
   2. Underside of belt should be free of any glazing/wax buildup.
   3. Rollers must also be free of wax buildup.
   4. Be sure belt tracking/centering is correct before proceeding.
   5. The most popular speed for this adjustment is 2mph to 3mph.
   6. Try to slow the belt by applying pressure with your foot against the belt movement while grasping the handrails. If the running belt slow, slips or stops (and the front roller does not) adjust BOTH adjustment bolts 1/4 turn clockwise. Test again and repeat adjustment if necessary.
2. This procedure requires two belt gauges or calipers
   1. This procedure works well when installing a new belt.
   2. This procedure requires you to stretch the belt. Depending on the manufacturer*, this varies between .4 and .6 percent. A dial on the gauge or caliper will indicate the amount of stretch. *Consult the owner/service manual for proper tension.
   3. If you are working on a previously tensioned belt you will need to release the tension before attaching the gauges or calipers.
3. Gauges or Calipers unavailable
   1. Release the tension on the belt.
   2. Using a yard stick or tape measure, place two marks on the left and right edges of the belt and deck 36 inches apart (or 50 inches if you prefer).
   3. Adjust the left and right tensioning bolts until both sides measure 36 3/16 inches (or 50 1/4). This is equal to .5% of stretch.
   4. Test for proper tracking and tension, adjust if necessary.

How to Tension Treadmill Walking Belt that Slips

When a running belt has excessive wear, it creates a lot of friction which causes the drive motor to work harder. When the drive motor works harder it will start overheating. If the belt is not lubricated periodically, it will ruin the deck, the drive motor, and cause other electrical problems such as tripping the breaker [after a while, the circuit breaker on the treadmill will need to be replaced. It is suggested to lubricate the belt every month. At this point, you may need to replace both your deck and your running belt. With your model and serial number, you can visit our website and view the products we have available for your particular machine. Precor Repair Parts for 9 1 9 10 Treadmills SPORTSMITH net

If the belt is worn on the underside you will definitely want to replace the belt. The link at the bottom will take you to a video on how to use a liquid lube on your treadmill. Lubricating the belt/deck every 30 days will prolong the life of the belt and the deck. The friction caused by excessive wear on the belt and/or the deck can cause a high amp draw and make the drive motor work harder than it's designed to. How to Lubricate Treadmill Using Liquid Lube Video

Precor Error 41, Lift has not Responded in Acceptable Time Probable Cause Error 41 was present in early software versions and is no longer being used. Corrective Action If you encounter a unit that has software with an error 41, diagnose the same way you would if getting an error 40. Precor Error 41 ****** Precor Error 40, No Lift Motion Detected Probable Cause 1. Blown lift fuse in lower PCA. 2. Lift motor is physically jammed and not able to move. 3. Bad lower PCA. 4. Bad lift capacitor. 5. Bad lift motor winding. 6. Bad interconnect cable between upper and lower PCA. 7. Bad upper PCA. Corrective Action

1. Check the lift fuse from the lower PCA. Using an ohmmeter, the fuse should measure 1 ohm or less. If the reading is significantly high, replace the fuse. If the fuse is open, refer to steps 3 and 4 before continuing.
2. Disconnect the lift motor from the ramp (elliptical) or lift platform (treadmill). If the lift nut or lift tube is jammed against the motor housing, turn the lift tube or lift nut away from the motor housing. If the lift was jammed, refer to step 3 before continuing. Calibrate the lift motor per the proper procedure for the unit being serviced and reattach the lift motor to the ramp (elliptical) or lift platform (treadmill). NOTICE: You must find and repair the cause for the jammed lift. Only re-calibrating the lift motor will not solve the problem.
3. One of two modes can cause the lower PCA to fail. The lift switch could fail in an operated condition. If this happens the lift will move (either up or down) as soon as the unit powers up. The usual result is that the lift will be physically jammed as explained above, and probably also being cause for the lift fuse to blow. The lift switch could also fail in an open condition. If this happened, the lift would not operate in one direction. If either of these conditions occur the lower PCA needs replaced.
4. Most units have the lift capacitor mounted inside the lift motor, and others use external lift capacitors. This information applies to units with the external lift capacitors. If the lift capacitor is shorted the lift fuse blows. Check the capacitor for a short using an ohm meter. Disconnect the capacitor from the lift motor and test. A good capacitor reads in the millions of ohms. Replace the capacitor if the reading is significantly low. Capacitor can also fail in the open condition which would result with the lift motor trying to run but not having normal power. Test the capacitor by measuring AC voltage across it. A good capacitor will read AC peak voltage while an open capacitor reads AC RMS voltage.
5. When a lift motor winding is bad the lift will not operate in one or both directions depending upon the exact fault in the motor. Check the lift motor winding with an ohm meter. AC lift motors have a split winding (3 wires) and DC lift motors will have a single winding. Both windings must be checked on an AC lift motor. Normal winding readings could vary anywhere between 1 and 60 ohms, depending on the lift motor being tested. See the proper service manual for the motor being tested.
6. Test unit with a known good interconnect cable. Replace the interconnect cable if necessary.
7. Test unit with a known good upper PCA. Replace the lower PCA if necessary.

Precor Error Code 40

Precor Error 70, LPCA Not Read Probable Cause Incorrect or missing software in the LPCA Corrective Action Test with a known good LPCA Precor Error 70 LPCA Not Read AMT12 Only

Precor Error 41, Lift has not Responded in Acceptable Time Probable Cause Error 41 was present in early software versions and is no longer being used. Corrective Action If you encounter a unit that has software with an error 41, diagnose the same way you would if getting an error 40. *** Precor Error 40, No Lift Motion Detected Probable Cause 1. Blown lift fuse in lower PCA. 2. Lift motor is physically jammed and not able to move. 3. Bad lower PCA. 4. Bad lift capacitor. 5. Bad lift motor winding. 6. Bad interconnect cable between upper and lower PCA. 7. Bad upper PCA. Corrective Action

1. Check the lift fuse from the lower PCA. Using an ohmmeter, the fuse should measure 1 ohm or less. If the reading is significantly high, replace the fuse. If the fuse is open, refer to steps 3 and 4 before continuing.
2. Disconnect the lift motor from the ramp (elliptical) or lift platform (treadmill). If the lift nut or lift tube is jammed against the motor housing, turn the lift tube or lift nut away from the motor housing. If the lift was jammed, refer to step 3 before continuing. Calibrate the lift motor per the proper procedure for the unit being serviced and reattach the lift motor to the ramp (elliptical) or lift platform (treadmill). NOTICE: You must find and repair the cause for the jammed lift. Only re-calibrating the lift motor will not solve the problem.
3. One of two modes can cause the lower PCA to fail. The lift switch could fail in an operated condition. If this happens the lift will move (either up or down) as soon as the unit powers up. The usual result is that the lift will be physically jammed as explained above, and probably also being cause for the lift fuse to blow. The lift switch could also fail in an open condition. If this happened, the lift would not operate in one direction. If either of these conditions occur the lower PCA needs replaced.
4. Most units have the lift capacitor mounted inside the lift motor, and others use external lift capacitors. This information applies to units with the external lift capacitors. If the lift capacitor is shorted the lift fuse blows. Check the capacitor for a short using an ohm meter. Disconnect the capacitor from the lift motor and test. A good capacitor reads in the millions of ohms. Replace the capacitor if the reading is significantly low. Capacitor can also fail in the open condition which would result with the lift motor trying to run but not having normal power. Test the capacitor by measuring AC voltage across it. A good capacitor will read AC peak voltage while an open capacitor reads AC RMS voltage.
5. When a lift motor winding is bad the lift will not operate in one or both directions depending upon the exact fault in the motor. Check the lift motor winding with an ohm meter. AC lift motors have a split winding (3 wires) and DC lift motors will have a single winding. Both windings must be checked on an AC lift motor. Normal winding readings could vary anywhere between 1 and 60 ohms, depending on the lift motor being tested. See the proper service manual for the motor being tested.
6. Test unit with a known good interconnect cable. Replace the interconnect cable if necessary.
7. Test unit with a known good upper PCA. Replace the lower PCA if necessary.

Precor Error Code 40

Precor Error 01, Memory, RAM, EEPROM Test Error Probable Cause This error message almost always indicate an upper PCA problem when they are consistently displayed. Failures causing this error message to be displayed are rare. Corrective Action If the error message is consistently displayed when the unit is powered up, the upper PCA should be replaced. It is possible to see this message displayed intermittently due to external causes. If the units A.C. input significantly dips during the power up test sequence the test could fail resulting in this message being displayed. Treadmills operating on non-dedicated A.C. circuits may see this message displayed on Precor Error Code 01

Precor Error Code 22 Error Code: 22 Manufacturer: Precor Model: All Models Error Description: Error 22, No Motor Pulses at Start Up - Error indicates that the display has sent a command for the drive motor to start, however, the speed sensor has not returned the signal acknowledging that the drive motor has started. Possible Reason:

1. The line of sight between the speed sensor and the speed sensor target is obstructed.
2. Badly worn drive motor brushes.
3. Incorrect gap between the speed sensor and the speed sensor target.
4. Incorrect adjustment of the speed sensor potentiometer (when equipped).
5. Inoperative speed sensor.
6. Faulty lower PCA.
7. Faulty interconnect cable between upper and lower PCA.
8. Faulty upper PCA.

Recommended Action:

1. Using a static safe vacuum cleaner, carefully vacuum out the drive motor compartment. Be sure to thoroughly clean the area between the speed sensor and the speed sensor target.
2. Bady worn drive motor brushes cannot make proper contact with the motor commutator, therefore the drive motor will not start when voltage is applied. Inspect and replace drive motor brushes if necessary.
3. Inspect the gap of the speed sensor to the speed sensor target. Proper gap is 3/16" and the speed sensor photo eye should be aimed at the larger portion of the targets wedge shaped section. If unit has a magnetic speed sensor, the gap between the end of the sensor and the flywheel tooth needs to be 3/16".
4. Locate the speed sensor potentiometer (when equipped) on the lower PCA. Set the speed sensor potentiometer to mid-range. Start the treadmill and increase speed to 6 mph. Carefully adjust the speed sensor potentiometer until the treadmill is operating the smoothest. Increase the speed to full speed and again adjust the speed sensor potentiometer until the treadmill is operating the smoothest. These two adjustments are typically small and are generally only a matter of fine tuning.
5. An inoperative speed sensor will allow the drive motor to start and run briefly before the error appears. If able to access the speed sensor wiring, measure the DC voltage between the speed sensor leads. Two of the leads will always read about 5 VDC. Two will toggle between 0 and 5 VDC as you slowly turn the speed sensor target. If both measurements are not seen, the speed sensor needs replaced. Some units have the speed sensor mounted on the lower PCA and the lower PCA needs replaced.
6. Determine if the lower PCA is bad by swapping with a known good lower PCA.
7. Determine if the interconnect cable is bad by swapping with a know good cable.
8. Determine if the upper PCA is bad by swapping with a know good upper PCA.

Precor Error Code 22

Precor Error 41, Lift has not Responded in Acceptable Time Probable Cause Error 41 was present in early software versions and is no longer being used. Corrective Action If you encounter a unit that has software with an error 41, diagnose the same way you would if getting an error 40. Precor Error 41

Precor Error 41, Lift has not Responded in Acceptable Time Probable Cause Error 41 was present in early software versions and is no longer being used. Corrective Action If you encounter a unit that has software with an error 41, diagnose the same way you would if getting an error 40. Precor Error 41 Precor Error 40, No Lift Motion Detected Probable Cause 1. Blown lift fuse in lower PCA. 2. Lift motor is physically jammed and not able to move. 3. Bad lower PCA. 4. Bad lift capacitor. 5. Bad lift motor winding. 6. Bad interconnect cable between upper and lower PCA. 7. Bad upper PCA. Corrective Action

1. Check the lift fuse from the lower PCA. Using an ohmmeter, the fuse should measure 1 ohm or less. If the reading is significantly high, replace the fuse. If the fuse is open, refer to steps 3 and 4 before continuing.
2. Disconnect the lift motor from the ramp (elliptical) or lift platform (treadmill). If the lift nut or lift tube is jammed against the motor housing, turn the lift tube or lift nut away from the motor housing. If the lift was jammed, refer to step 3 before continuing. Calibrate the lift motor per the proper procedure for the unit being serviced and reattach the lift motor to the ramp (elliptical) or lift platform (treadmill). NOTICE: You must find and repair the cause for the jammed lift. Only re-calibrating the lift motor will not solve the problem.
3. One of two modes can cause the lower PCA to fail. The lift switch could fail in an operated condition. If this happens the lift will move (either up or down) as soon as the unit powers up. The usual result is that the lift will be physically jammed as explained above, and probably also being cause for the lift fuse to blow. The lift switch could also fail in an open condition. If this happened, the lift would not operate in one direction. If either of these conditions occur the lower PCA needs replaced.
4. Most units have the lift capacitor mounted inside the lift motor, and others use external lift capacitors. This information applies to units with the external lift capacitors. If the lift capacitor is shorted the lift fuse blows. Check the capacitor for a short using an ohm meter. Disconnect the capacitor from the lift motor and test. A good capacitor reads in the millions of ohms. Replace the capacitor if the reading is significantly low. Capacitor can also fail in the open condition which would result with the lift motor trying to run but not having normal power. Test the capacitor by measuring AC voltage across it. A good capacitor will read AC peak voltage while an open capacitor reads AC RMS voltage.
5. When a lift motor winding is bad the lift will not operate in one or both directions depending upon the exact fault in the motor. Check the lift motor winding with an ohm meter. AC lift motors have a split winding (3 wires) and DC lift motors will have a single winding. Both windings must be checked on an AC lift motor. Normal winding readings could vary anywhere between 1 and 60 ohms, depending on the lift motor being tested. See the proper service manual for the motor being tested.
6. Test unit with a known good interconnect cable. Replace the interconnect cable if necessary.
7. Test unit with a known good upper PCA. Replace the lower PCA if necessary.

Precor Error Code 40

Precor Error Code 22 Error Code: 22 Manufacturer: Precor Model: All Models Error Description: Error 22, No Motor Pulses at Start Up - Error indicates that the display has sent a command for the drive motor to start, however, the speed sensor has not returned the signal acknowledging that the drive motor has started. Possible Reason:

1. The line of sight between the speed sensor and the speed sensor target is obstructed.
2. Badly worn drive motor brushes.
3. Incorrect gap between the speed sensor and the speed sensor target.
4. Incorrect adjustment of the speed sensor potentiometer (when equipped).
5. Inoperative speed sensor.
6. Faulty lower PCA.
7. Faulty interconnect cable between upper and lower PCA.
8. Faulty upper PCA.

Recommended Action:

1. Using a static safe vacuum cleaner, carefully vacuum out the drive motor compartment. Be sure to thoroughly clean the area between the speed sensor and the speed sensor target.
2. Bady worn drive motor brushes cannot make proper contact with the motor commutator, therefore the drive motor will not start when voltage is applied. Inspect and replace drive motor brushes if necessary.
3. Inspect the gap of the speed sensor to the speed sensor target. Proper gap is 3/16" and the speed sensor photo eye should be aimed at the larger portion of the targets wedge shaped section. If unit has a magnetic speed sensor, the gap between the end of the sensor and the flywheel tooth needs to be 3/16".
4. Locate the speed sensor potentiometer (when equipped) on the lower PCA. Set the speed sensor potentiometer to mid-range. Start the treadmill and increase speed to 6 mph. Carefully adjust the speed sensor potentiometer until the treadmill is operating the smoothest. Increase the speed to full speed and again adjust the speed sensor potentiometer until the treadmill is operating the smoothest. These two adjustments are typically small and are generally only a matter of fine tuning.
5. An inoperative speed sensor will allow the drive motor to start and run briefly before the error appears. If able to access the speed sensor wiring, measure the DC voltage between the speed sensor leads. Two of the leads will always read about 5 VDC. Two will toggle between 0 and 5 VDC as you slowly turn the speed sensor target. If both measurements are not seen, the speed sensor needs replaced. Some units have the speed sensor mounted on the lower PCA and the lower PCA needs replaced.
6. Determine if the lower PCA is bad by swapping with a known good lower PCA.
7. Determine if the interconnect cable is bad by swapping with a know good cable.
8. Determine if the upper PCA is bad by swapping with a know good upper PCA.

Precor Error Code 22

Precor Error Code 21 Error Code: 21 Manufacturer: Precor Model: All Models Error Description: Error 21, Too many Consecutive Power Requests- The error 21 observes a treadmill's power bit reading when the treadmill was operating at speeds above 1 mph. Power bits indicate the relative time that the motor controller drive circuit is turned on. Power bits is an indication of the amount of power the load is demanding from the motor controller. Error 21 indicates that at a speed greater than 1 mph, an excessive amount of power is being demanded from the motor controller. Possible Reason:

1. A badly worn deck and/or running belt can cause the error to appear when the unit is in use.
2. Badly worn drive motor brushes may not be making proper contact with the drive motor commutator causing the error to occur when the unit is in use. The unit may also slow down or become sluggish when the load or speed is increased.
3. A jumper may be required on the lower PCA if installed into a 120 VAC (Version 2) treadmill.
4. A leaky or shorted drive motor filter capacitor (on units equipped with SCR motor controller) could increase the current demand enough to cause the error.
5. A leaky or shorted drive motor inductor (on units equipped with SCR motor controller) could increase the current demand enough to cause the error.
6. The high power demand is caused by a shorted or de-magnetized drive motor.

Recommended Action:

1. Determine the amount of AC input current being drawn by the unit under no load and loaded conditions using a clamp on AC ammeter. The current displayed can be used to determine the condition of the deck and/or running belt. These same readings should be taken on a like unit, in good operating condition with a know good deck and running belt. The readings from the unit in good operationg condition can be used as the benchmark. Compare readings and replace* the deck and/or running belt if necessary. *Some units have a reversible deck. Be sure if the deck is being flipped or replaced, a new belt is installed on the new deck surface.*
2. Inspect and repalce both drive motor brushes if necessary.
3. Inspect the lower PCA (if unit is 120 VAC/ Version 2) for jumper. If jumper is not installed, error typically appears between 7 mph & 8 mph. Install jumper if necessary. CAUTION - DO NOT install jumper if unit is 240 VAC. Installing the jumper on a 240 VAC unit will casue the lower PCA to fail.
4. Measure the AC input current without a load using a clamp on AC ammeter. Electrically isolate the filter capacitor from the drive motor circuit. The drive motor leads need be kept intact so the drive motor will operate with the filter capacitor removed from the circuit. Re-measure the no load AC input. If the AC input current is significantly lower, replace the filter capacitor.
5. Measure the AC input current without a load using a clamp on AC ammeter. Electrically isolate the inductor from the drive motor circuit. The drive motor leads need be kept intact so the drive motor will operate with the inductor removed from the circuit. Re-measure the no load AC input. If the AC input current is significantly lower, replace the inductor.
6. Swap the existing drive motor with a known good drive motor.

Precor Error Code 21

About This Video

Video about How to Lubricate a Treadmill using Liquid Lube

• This vidoe will demonstrate how to properly lubricate your treadmill belt and deck. This demonstration is for the application of liquid lube.
• To begin, clean the deck and belt by loosening the rear roller bolts 10 turns as seen in the video. It is best to loosen each side five turns and then repeat the process.
• Now that the belt is loose you can take an old towel and place it under the belt as shown in the video. Move the towel up and down the deck, then using your hands pull the belt around half way to ensure you have completely cleaned the back of the belt. Then remove the towel.
• Open your lube packet and use half of the package to make a half circle on the deck, from the front outer portion of the deck toward the center and then back to the outer edge. Use about half the package for this arc. Now repeat the process on the opposite side. Be sure to wipe up any excess oil as it is very slick!
• Use your hand to move the belt around some more to begin spreading the lubricant out.
• Now tighten the rear roller bolts back to the exact amount of turns they were loosened previously.
• Power on and start the machine and let it run slowly for a few seconds to make sure the belt is staying aligned in the center of the deck area. If it is not centered correctly, make minor adjustments to correct the issue. Tighten the left bolt to move the belt to the right and tighten the right bolt to move the belt to the left. Now walk on the belt for a minute or so to fully distribute the lubricant.
• This concludes todays demonstration of how to lubricate a treadmill using the liquid lube.

How to Lubricate Treadmill Using Liquid Lube Video

Precor Error Code 22 Error Code: 22 Manufacturer: Precor Model: All Models Error Description: Error 22, No Motor Pulses at Start Up - Error indicates that the display has sent a command for the drive motor to start, however, the speed sensor has not returned the signal acknowledging that the drive motor has started. Possible Reason:

1. The line of sight between the speed sensor and the speed sensor target is obstructed.
2. Badly worn drive motor brushes.
3. Incorrect gap between the speed sensor and the speed sensor target.
4. Incorrect adjustment of the speed sensor potentiometer (when equipped).
5. Inoperative speed sensor.
6. Faulty lower PCA.
7. Faulty interconnect cable between upper and lower PCA.
8. Faulty upper PCA.

Recommended Action:

1. Using a static safe vacuum cleaner, carefully vacuum out the drive motor compartment. Be sure to thoroughly clean the area between the speed sensor and the speed sensor target.
2. Bady worn drive motor brushes cannot make proper contact with the motor commutator, therefore the drive motor will not start when voltage is applied. Inspect and replace drive motor brushes if necessary.
3. Inspect the gap of the speed sensor to the speed sensor target. Proper gap is 3/16" and the speed sensor photo eye should be aimed at the larger portion of the targets wedge shaped section. If unit has a magnetic speed sensor, the gap between the end of the sensor and the flywheel tooth needs to be 3/16".
4. Locate the speed sensor potentiometer (when equipped) on the lower PCA. Set the speed sensor potentiometer to mid-range. Start the treadmill and increase speed to 6 mph. Carefully adjust the speed sensor potentiometer until the treadmill is operating the smoothest. Increase the speed to full speed and again adjust the speed sensor potentiometer until the treadmill is operating the smoothest. These two adjustments are typically small and are generally only a matter of fine tuning.
5. An inoperative speed sensor will allow the drive motor to start and run briefly before the error appears. If able to access the speed sensor wiring, measure the DC voltage between the speed sensor leads. Two of the leads will always read about 5 VDC. Two will toggle between 0 and 5 VDC as you slowly turn the speed sensor target. If both measurements are not seen, the speed sensor needs replaced. Some units have the speed sensor mounted on the lower PCA and the lower PCA needs replaced.
6. Determine if the lower PCA is bad by swapping with a known good lower PCA.
7. Determine if the interconnect cable is bad by swapping with a know good cable.
8. Determine if the upper PCA is bad by swapping with a know good upper PCA.

Precor Error Code 22

Precor Error Code 22 Error Code: 22 Manufacturer: Precor Model: All Models Error Description: Error 22, No Motor Pulses at Start Up - Error indicates that the display has sent a command for the drive motor to start, however, the speed sensor has not returned the signal acknowledging that the drive motor has started. Possible Reason:

1. The line of sight between the speed sensor and the speed sensor target is obstructed.
2. Badly worn drive motor brushes.
3. Incorrect gap between the speed sensor and the speed sensor target.
4. Incorrect adjustment of the speed sensor potentiometer (when equipped).
5. Inoperative speed sensor.
6. Faulty lower PCA.
7. Faulty interconnect cable between upper and lower PCA.
8. Faulty upper PCA.

Recommended Action:

1. Using a static safe vacuum cleaner, carefully vacuum out the drive motor compartment. Be sure to thoroughly clean the area between the speed sensor and the speed sensor target.
2. Bady worn drive motor brushes cannot make proper contact with the motor commutator, therefore the drive motor will not start when voltage is applied. Inspect and replace drive motor brushes if necessary.
3. Inspect the gap of the speed sensor to the speed sensor target. Proper gap is 3/16" and the speed sensor photo eye should be aimed at the larger portion of the targets wedge shaped section. If unit has a magnetic speed sensor, the gap between the end of the sensor and the flywheel tooth needs to be 3/16".
4. Locate the speed sensor potentiometer (when equipped) on the lower PCA. Set the speed sensor potentiometer to mid-range. Start the treadmill and increase speed to 6 mph. Carefully adjust the speed sensor potentiometer until the treadmill is operating the smoothest. Increase the speed to full speed and again adjust the speed sensor potentiometer until the treadmill is operating the smoothest. These two adjustments are typically small and are generally only a matter of fine tuning.
5. An inoperative speed sensor will allow the drive motor to start and run briefly before the error appears. If able to access the speed sensor wiring, measure the DC voltage between the speed sensor leads. Two of the leads will always read about 5 VDC. Two will toggle between 0 and 5 VDC as you slowly turn the speed sensor target. If both measurements are not seen, the speed sensor needs replaced. Some units have the speed sensor mounted on the lower PCA and the lower PCA needs replaced.
6. Determine if the lower PCA is bad by swapping with a known good lower PCA.
7. Determine if the interconnect cable is bad by swapping with a know good cable.
8. Determine if the upper PCA is bad by swapping with a know good upper PCA.

Precor Error Code 22

worn running belt and deck. You can try to clean the belt a bit using a clean towel and running it under the belt and stand on both ends. turn the tread on and let it run for a minute or so at 2mph. hit stop and pull the towel out. make sure the tread doesn't share a circuit with the fridge or a freezer, etc. As they wear the amp draw gets greater and if its sharing the circuit it will trip more and more. Understand, please, that every time it shuts off it is because of heat in the electronics from the extra work it is doing to push/pull that running belt over an increasingly sticky surface. The cost of reoplacing a deck and belt (the deck may be two sided and be flipped) is a lot less than eating the lower power control board and/or a drive motor. Also, do the drive belt while you are doing the run belt. Don't scrimp on that $40 as it will haunt you later.