How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29439
Experience:  GM Grand Master Technician 2007. 14 years experience.
10949255
Type Your Chevy Question Here...
GM Tech (Cam) is online now
A new question is answered every 9 seconds

Service Traction Control problem on Chevrolet Impala

Customer Question

Service Traction Control message displayed followed by engine power will be reduced message. Both Traction Contol light and Engine Check light are both on. What's going bad?
Submitted: 5 years ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 5 years ago.

GM Tech (Cam) :

Hello, Please include all the details about your issue, so I can accurately advise you. I cannot see your vehicle so please be detailed.

This is often a problem with the throttle body, wiring to the throttle body or even the fuel pedal itself.

JACUSTOMER-ksckzbu2- :

While driving - steady state on DC beltway at

No real reduction in performance.This is the second occurence of the same event. First event happened about a month ago under same conditions. Lights cleared themselves. No apparent problem.

GM Tech (Cam) :

Then I would suggest you check the wiring for the throttle body and pedal and see if there is anything obvious in there.

JACUSTOMER-ksckzbu2- :

What would I be checking for? Corrosion? I have had no service done on the engine (other than oil changes) in over a year.

GM Tech (Cam) :

Yes, corrosion called fretting, which is a micro corrosion in the terminals.

JACUSTOMER-ksckzbu2- :

OK, do you disconnect the wire bundle and clean? If it's micro corrosion, would it be visible?

GM Tech (Cam) :

Disconnect and connect is often all it takes but can out some electronics grease in there to stop it

JACUSTOMER-ksckzbu2- :

I called the dealer and they are saying timing chain... And possibly other major issues. Is it easy access? I'm not a mechanic, but I'm willing to do some basic stuff.

Where do I find this harness?

GM Tech (Cam) :
They are on the fuel pedal and the the throttle body where the air filter duct goes into the engine.

We would need the codes to be sure. For them to guess a major issue is not good. However if it so, then it may be covered under power train warranty.

JACUSTOMER-ksckzbu2- :

I am just out of warranty work... 107K miles

GM Tech (Cam) :

Ask for goodwill warranty.

JACUSTOMER-ksckzbu2- :

Hmmm, never heard of that one.

GM Tech (Cam) :

They don't want you to know about it

JACUSTOMER-ksckzbu2- :

Of course...

JACUSTOMER-ksckzbu2- :

If I go to an auto zone type store, they could check codes - right? Are they reliable?

GM Tech (Cam) :

They may or may not.

JACUSTOMER-ksckzbu2- :

Great

GM Tech (Cam) :

yes they can get the codes.

JACUSTOMER-ksckzbu2- :

Can they interpet the codes? Or best to bring them back to you?

GM Tech (Cam) :

Bring them back to me.

JACUSTOMER-ksckzbu2- :

OK. I'll stop by the auto zone near my house and have them check codes. I'll find the electrical connection, and get back to you tomorrow.

Given what I told you, is the car safe to drive? I have a trip to make tomorrow - ~200 miles.

GM Tech (Cam) :

The only danger is if the system lost power.

JACUSTOMER-ksckzbu2- :

Any damage? I can live with reduced performance if I don't do any damage.

GM Tech (Cam) :

No, it should not damage anything

GM Tech (Cam) and 5 other Chevy Specialists are ready to help you
Customer: replied 5 years ago.

HI, I went to a nearby Auto Zone for a diagnostic check. The code that got reported was P2138.

Definition: APP sensor 1 and APP sensor 2 signal voltage fault.

Explanation: The ECM has detected the APP sensor signal 1 & 2 do not agree.

Probable cause: Poor electrical connection, or Failed APP sensor.

I made my trip yesterday without any problem. In fact, all the warning lights have cleared, and the car is performing normally - no problems.

My assessment is that you were spot on with a cause - bad connection - corrosion (probably). Is the APP sensor tied to the gas pedal? Looks like there is an immediate pedal to sensor connection.

Expert:  GM Tech (Cam) replied 5 years ago.

Yes, because this has been electronic throttle, the app sensor is the fuel pedal sensor.

Customer: replied 5 years ago.
Thanks
Expert:  GM Tech (Cam) replied 5 years ago.
My pleasure.