2003 saturn L300 p1780 - 2003 Saturn L-Series

DTC P1780
Circuit Description
This DTC indicates that the engine control module (ECM) received a message from the transmission control module (TCM) to turn ON the MIL (SERVICE ENGINE SOON) telltale due to a transmission related OBD II failure. The ECM will send a message via the controller area network (CAN) link to the body control module (BCM), which will send a message over the class 2 link to the instrument panel (I/P) cluster to turn ON the MIL.
Conditions for Setting the DTC
DTC P1780 will set if the ECM received a MIL request message from the TCM over the CAN link.
DTC P1780 is a type B DTC.
Diagnostic Aids
DTC P1780 does not indicate a fault with the CAN link circuit.
DTC P1780 does not indicate a fault with the ECM.
Diagnose any TCM related DTCs first.


You need a scan tool that can read transmission control module codes .

#PIP3922: Repeat DTC P0606 And P1780 Setting - keywords 00 01 02 03 04 05 DTC JB L81 MAF MIL P0606 P1780 reducedpwrmde reman saturn - (Sep 26, 2006)

Subject: Repeat DTC P0606 and P1780 Setting

Models: 2000-2005 Saturn L series with L81 V6 The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
A technician may find codes P0606 and P1780 setting. They may state that they are not able to duplicate the concern. Tech may state that when the customer is driving they report a sudden loss of power, then no throttle response, and the warning indicators come on. Tech may also state that the ECM and MAF were replaced with no change.
Recommendation/Instructions:
These codes will set if the wrong MAF was installed on the vehicle previously. This being an intermittent code the MAF may work without any concerns initially. The retailer may not be aware of 2 different part number MAF's for 2000-05 L series with L81. Compounding this is the reman sticker may fall off and GM does not cross reference the Bosch part number to theirs. Any time these codes are setting have technician verify the correct MAF is installed using the reference below
The part numbers are:
2000-03 90528435 Last 3 of Bosch # 184 (important because the reman sticker may be missing)
2004-05 24437651 Last 3 of Bosch # 087 (important because the reman sticker may be missing)
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
GM bulletins are intended for use by professional technicians, NOT a ""do-it-yourselfer"". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
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Gm p1780 is torque converter clutch problems undefined on a saturn?

P1780 Park/Neutral Postion (PNP) Switch Circuit Engine Torque Signal Circuit

This is an indication that the TCM is not function properly As it is an automatic the gears in constant mesh with gear changes being effected by clutch packs and bands so the ratios are always correct just the selection is not working properly./ Hence the TCM fault.

how old is the battery?

No i have never Never seen a issue with this saturn or any other saturn or gm car for this problem,,,