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I've had an intermitted issue with my 09 GXP for a few years now and nobody has been able to figure it out. The car will go into engine power reduced and the service TC and ESC comes on. Typically it would do it randomly and i could just clear the codes but now I cant clear the codes and it is always in limp mode. I've replaced the accelerator position sensor twice, throttle body, and PCM. A shop tested for leaks and the wiring and no issues were found.

I was hoping someone has the wiring diagram for the circuit or if others had a similar issue and could point me in the right direction.

Thanks
 

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Probably wouldn't hurt to look into the BCM connector, because it can't hurt.
GM Bulletin 13036. Skip ahead to the BCM connector. Locate it, and install grease.
No guarantees, but from what I have seen over the years, it has cured quite a few intermittent ESC, ABS, TCS with other sometimes non&related faults.

Sent from my moto g power using Tapatalk

Sent from my moto g power using Tapatalk
 

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I've had an intermitted issue with my 09 GXP for a few years now and nobody has been able to figure it out. The car will go into engine power reduced and the service TC and ESC comes on. Typically it would do it randomly and i could just clear the codes but now I cant clear the codes and it is always in limp mode. I've replaced the accelerator position sensor twice, throttle body, and PCM. A shop tested for leaks and the wiring and no issues were found.

I was hoping someone has the wiring diagram for the circuit or if others had a similar issue and could point me in the right direction.

Thanks
Definitely sounds like BCM connection issue. As previously stated there is a service bulletin to clean and grease the connection at the BCM. My 07 GTP did this several times. Unplugging the BCM, checking all the pins for proper seating in the connection and lubricating the pins with dielectric grease fixed the problem. I haven’t had an issue with the traci or ABS light for over 3 years now since I did this really easy repair. BCM is behind the right side of shifter console kick panel.
good luck!
 

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I've had an intermitted issue with my 09 GXP for a few years now and nobody has been able to figure it out. The car will go into engine power reduced and the service TC and ESC comes on. Typically it would do it randomly and i could just clear the codes but now I cant clear the codes and it is always in limp mode. I've replaced the accelerator position sensor twice, throttle body, and PCM. A shop tested for leaks and the wiring and no issues were found.

I was hoping someone has the wiring diagram for the circuit or if others had a similar issue and could point me in the right direction.

Thanks
Have you fixed the issue yet? My advise is based on the OBDII codes 2132 and 2138
I've had an intermitted issue with my 09 GXP for a few years now and nobody has been able to figure it out. The car will go into engine power reduced and the service TC and ESC comes on. Typically it would do it randomly and i could just clear the codes but now I cant clear the codes and it is always in limp mode. I've replaced the accelerator position sensor twice, throttle body, and PCM. A shop tested for leaks and the wiring and no issues were found.

I was hoping someone has the wiring diagram for the circuit or if others had a similar issue and could point me in the right direction.

Thanks
Have you fixed the issue yet? My advice is solely based on the OBDII 2127 and 2138 which indicate a low reference circuit (Pin E) and voltage circuit (Pin D) issues in the PPS. The resolution for these two codes require that you access the PPS sensor connector and the Throttle body connector. You will need to test the connection between the PPS and the Engine Control Module (or PCM in your car) and between the PCM and the Throttle body. That means you have to find out what pins at the PCM connectors need to be tested. I do not have the connectors views for your GPX 2009 but I think it maybe very similar to all other G6 sub models. Once the circuits have been verified, you have two options to resolve the issue. The easy way (but more expensive) is to replace the TB. The other is to verify the TB components (gasket, tabs, orientation etc.) There is a specific procedure to do so. It may be similar to GM # 12-06-04-003A: Malfunction Indicator Lamp (MIL) Illuminated, Reduced Engine Power Message Displayed, DTC P2135 Set - (Mar 24, 2014) which was issued for the LZ4 and LZ9 engines. But I can't be for sure on the GXP model.
 

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I had a similar problem with my son's 2009 GT.

There was a loss of the 5 Volt 2 source from the ECM. This feeds the throttle control and the pedal position sensor.

There are two sources of the 5 volts to the sensor. 5V1 and 5V2, if either are missing then the ECM puts the car in limp mode.

What I found is a broken wire inside the insulation for the harness from the ECM to the X108 plug near the left fender under the hood. The way the wiring harness is installed keeps too much stress on the individual wires and they can be damaged.
A copy of the schematic shows only two places using the 5V2 source. I also have attached a copy of the throttle body connector. If the 5V2 is missing then it needs to be traced back to X108. The connectors to the ECM are not likely to be a problem.
I hope that this may help some one who is looking at this circuit for limp mode issues.
 

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