[kallell]

P2138 Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation 2008 Cadillac cts

Hi All,

Recently had my car, while on the interstate, tell me to "service traction control" and "reducing engine power." Initially it was happening pretty sporadically, and only while driving on the interstate. Over the following weeks, it appears as the issue crops up more and more, regardless of where or how fast i'm driving. Upon looking in to it, it appears among a few codes was a P2138 - Powertrain - Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation code. After some research many pointed to the throttle body being faulty. So, I cleaned the current throttle body - no luck. Next, I replaced the entire throttle body - no luck. After some more research, many pointed to the accelerator pedal assembly. Replaced that with a new one - no luck. So i'm kind of out of ideas, on what I could be replacing next or looking at to try to fix the issue. If anyone has any suggestions, I'd love to hear them.

Thanks,
Kal

 

[CaddyFred]

It might be useful to know what the other codes were. Did you perform the necessary TPS re-calibration? From the OM:

After a power loss, such as disconnecting the battery or
removing the maxi fuses in the power distribution fuse
block, the following steps must be performed to calibrate
the electronic throttle control. If this is not done, the
engine will not run properly.
1. Turn the ignition to ON/RUN. Do not start the
engine.
2. Leave the ignition in ON/RUN for at least
three minutes so that the electronic throttle
control will cycle and re-learn its home position.
3. Turn the ignition to LOCK/OFF.
4. Start and run the engine for at least 30 seconds.

If that doesn't help, try a thorough inspection and cleaning of the electrical contacts at both the TB and pedal connections.

 

[silversport]

also it is helpful when people fill out the type of vehicle they have and the particulars in their vehicle profile...good luck with your vehicles issues...

Bill

 

[Drunken Elvis]

Many GM vehicles suffer from corrosion at the electrical connections. This includes the large connectors of the Body Control Module and the Engine Control Module. No vehicle year/type is specified here but the throttle position sensor of a 2008 CTS 3.6 DI mates to the ECM using pins 34,46,47 and 48 of connector 2. With the battery disconnected, removing and fully installing the ECM connectors a few times might help clean the pins. Be sure to fully seat the connectors when done and ensure they are sealed from the elements

 

[Padgett]

Torque Pro is good for displaying the parameters such as throttle position request. Would be helpful to use to diagnose otherwise you are just throwing money at it.

 

[kallell]

Many GM vehicles suffer from corrosion at the electrical connections. This includes the large connectors of the Body Control Module and the Engine Control Module. No vehicle year/type is specified here but the throttle position sensor of a 2008 CTS 3.6 DI mates to the ECM using pins 34,46,47 and 48 of connector 2. With the battery disconnected, removing and fully installing the ECM connectors a few times might help clean the pins. Be sure to fully seat the connectors when done and ensure they are sealed from the elements

2008 cadillac cts

Sorry, thought i had that in the original post.

 

[kallell]

Just want to give a quick update on this. The connectors are fine, the accelerator pedal is fine, the throttle body is fine, it doesn't need to be calibrated, i didn't see any obvious corrosion.

The issue (so it seems) is that some of the main wiring running under the hood was old and braking apart, which was slowly getting worse and would occasionally short out. Replaced some of the wires and it seems to be better.

 

[Drunken Elvis]

Thanks for the update. Hope all is well.

 

[Padgett]

That will do it. Incidentally rodents love rubber but do not like moth balls. That said remove before driving.