Engine code P1781

[lmholmes11]

I posted this under 2500HD Drivetrain thread but no one responded to it, So I figured I had nothing to loose posting it here.

The light first went on a week or two ago, and has been coming on once in a while since then. It only comes on after I start the truck, it has never came on while driving. Any input? Should I update the TCM?

[lmholmes11]

Does anyone have any suggestions?

[tx dave]

P1781 is listed as Engine Torque Signal Circuit. I'm not a duramax mechanic. So when my 2001 2500HD throws acode I don't understand I run it by the dealer and talk with one of the mechanics for advice. Usually they are very helpful and can tell you if its something you can do yourself or if you need to turn it in. Sorry tis is the best I can tell you. Maybe one of the d-max mech out there can say something else. Good luck.

[DmaxMaverick]

You'll need a scanner to read the TCM codes. There should be a corresponding P07xx code present, but you can't read it in the PCM. In all likelihood, it's a connector or voltage issue. Perhaps some corrosion/moisture causing the DTC. Low battery voltage, especially during a start cycle, can cause any weak electrical connection to indicate a problem that doesn't really exist. Have you had the TCM read for codes? Start there. If the codes don't seem to line up with one specific failure, or there are no TCM codes, it's more likely an electrical connection than anything else.

[lmholmes11]

Thanks guys,

I have been thinking of getting new batteries lately and this just confirms that I should. Thanks again for the replys