6L90E - Stuck in THIRD Gear - P0807/P0723 Codes

[Crackerbuzz]

Hi all,

We are in the middle of an LSA swap with the stock E67 ECM from a 2013 CTSV.

We are having a P0807 code and a P0723 code and the transmission is limping in third gear.

Have you guys seen this before and do you have any ideas of what might be going on?

Thanks in advance!

Craig

[Jon S.]

Are all components (E67 ECM, APP, engine, transmission) from the same 2013 LSA 6L90 CTS-V ?

P0807 (ECM DTC) is the Clutch Position Sensor circuit - manual transmission vehicles only. This DTC should not be set by the above ECM.

P0723 (TCM DTC) is the OSS circuit - having an intermittent signal. The TCM would normally also set a P0700 DTC.

You never posted the calibration. Is the ECM from a manual transmission vehicle ?

[Crackerbuzz]

Are all components (E67 ECM, APP, engine, transmission) from the same 2013 LSA 6L90 CTS-V ?

P0807 (ECM DTC) is the Clutch Position Sensor circuit - manual transmission vehicles only. This DTC should not be set by the above ECM.

P0723 (TCM DTC) is the OSS circuit - having an intermittent signal. The TCM would normally also set a P0700 DTC.

You never posted the calibration. Is the ECM from a manual transmission vehicle ?

Hi Jon,

Yes, the P0807 has confused us too...

Sorry, Yes all of the components are from a dismantled CTSV. Automatic transmission, ECM and harness all came with the engine.

Thanks

[Jon S.]

Thank you for the additional information.

If all physical components are matched, and are in good working order, then the issues are likely wiring related.

Is the wiring harness new (from an aftermarket supplier), or did someone rework the used GM wiring harness ?

I have had several experiences where a corrupt wiring harness would cause nonsensical DTCs to be set.

Confirm the battery voltage circuits (constant 12 volts), ignition voltage circuits (key on 12 volts), and ground circuits. You may need to check every wire in the wiring harness for continuity, a short to ground (more common), or a short to voltage (less common).

[Crackerbuzz]

Thank you for the additional information.

If all physical components are matched, and are in good working order, then the issues are likely wiring related.

Is the wiring harness new (from an aftermarket supplier), or did someone rework the used GM wiring harness ?

I have had several experiences where a corrupt wiring harness would cause nonsensical DTCs to be set.

Confirm the battery voltage circuits (constant 12 volts), ignition voltage circuits (key on 12 volts), and ground circuits. You may need to check every wire in the wiring harness for continuity, a short to ground (more common), or a short to voltage (less common).

Thanks Jon,

That's good info. Yes we have seriously re-worked the harness so have probably mixed up a pin-out.

Cheers, we will work our way through this.

[Crackerbuzz]

ok guys,

So we got the thing running really good.

The issue was that some of the codes were not actually turning off until you hovered over the RH side of the DTC and chose what ACTION to take when the code was issued. This is completely different from simply ticking the boxes on the DTC lists. (I guess most of you probably already knew this!!!)

All codes to do with the body modules and other deleted stuff no longer created actions so she fired straight up and started shifting through gears perfectly!

Cheers for your help...

Craig