My 1997 dodge neon sohc auto check engine light is on with engine code p1491(open or shorted condition dectected in the radiator fan relay circuit) fan runs all the time with key on or off. replaced fan relay. fan now doesn't come on at any time even when the engine is hot. have also replaced temperature sending unit in head and replaced PCM on car still no results engine light still on.

Radiator Fan Control Relay Circuit
An open or shorted condition detected in the radiator fan control relay control circuit. This includes PWM solid state relays

P1491 Rad Fan Control Relay Circuit An open or shorted condition detected in the radiator fan control relay control circuit. This includes PWM solid state relays.P1495 Leak Detection Pump Solenoid Circuit An open or shorted condition detected in the Leak Detection Pump (LDP) solenoid circuit.P0753 (M) Trans 3-4 Shift Sol/Trans Relay Circuits An open or shorted condition detected in the overdrive solenoid control circuit or Trans Relay Circuit in JTEC RE transmissions. Was MIL code 45. P0753 (M) Trans 3-4 Shift Sol/Trans Relay Circuits An open or shorted condition detected in the transmission 2-4 shift solenoid circuit (4-speed auto. trans. only).P0136 (M) 1/2 O2 Sensor Heater Circuit Malfunction Oxygen sensor heater element malfunction.

Aside from getting into an accident and having your wiring harness severely damaged, the other likely suspect is your PCM. These codes are not related to each other and indicate a much larger problem.

Here's a link to the P0340 code,and P1491.Powertrain Diagnostics Manual P-1491 Radiator Fan control relay circuit
Set condition: An open or shorted condition is detected in the radiator fan relay control circuit.

Possibilities:
Fan relay ground circuit open
Fused B+ circuit open
Rad fan control relay defective
RF relay output circuit volt cycles over to batt voltage
RF relay control circuit open
RF relay ctrl rly ckt wir harness observable or intermittant defect
RF relay ctrl ckt short to ground
Defective PCM

Get out your Multimeter.

I need to know where the p1491 radiator relay control circuit is ?

P1491 - Radiator Fan Control Relay Circuit Open Or Shorted

When monitored: with the ignition key on, battery voltage greater than 10.0 volts and
the pcm requests the radiator fan to be turned on.
Set condition: an open or shorted circuit is detected in the radiator fan relay control
circuit.

Possible causes
radiator fan ctrl rly circuit wire harn intermittent defect
radiator fan ctrl rly circuit wire harn observable defect
radiator fan relay ground circuit open
rad fan relay control circuit open
radiator fan relay control circuit short to ground
rad fan control relay defective
pcm defective

Check ot and keep us updared.

Hello jhonney21,

The P1491 is Radiator fan control relay circuit code. It is set if an open or short circuit is detected in the radiator fan relay control circuit.

Regards,
netvan

Trouble code P1491 means: Radiator fan relay control circuit problem.

you have an open or shorted condition detected in the low speed radiator fan relay control circuit. hope this will help!!!!

It is for the radiator fan relay control circuit.It means there is a problem in the cooling fan relay circuit.Could be the relay,wiring,or the fans.Check the fuses and relay over if it looks good then you have to take it in to get it diagnosed.You need a scan tool and you also need to know how to use a multimeter.Hope this helps.Good luck.

P1491 is Radiator Fan Control Relay Circuit. MEANING: An open or shorted condition detected in the low speed radiator fan control circuit.
Some questions for you:
1. Is your Caravan overheating?
2. Is your Caravan water temperature spiking going past the midway point on the Temp Gauge before the radiator is engaged?
3. Is your Rad Fan coming-on and then turning off and back-on in a very short period of time (like under a minute?
If all of these are "No" then do not worry about it.