GM 3800 Traction Control Reduced power

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I bought a new car. 2004 Pontiac Grand Prix 92,000 miles. All the oil changes work done and in and out of the shop for regular inspections. Elderly owned and had been sitting 45- 90 days.

Yesterday, first time I hit the gas a bit hard it seemed to die.. but didn’t.. couldn’t get power. the traction control light and reduced power came on. Drove it to auto zone... 8 miles And it went a little faster and a little faster as time went on. p1125 Pedal acceleration position- p2138 Throttle pedal position sensor switch DE voltage- c0245 Wheel sensor speed malfunction- co240 PCM traction control not allowed. Engine warning light.

The man at AutoZone said it’s in the loop try to drive it a while on the highway. I did and it got better and better traction warning it reduce power went off...and after 35-50 miles the engine warning light went out. Drove 150 highway miles fine.


This morning it just did it again. Any thoughts?

Thanks
 
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Check the TPS, because that would cause a check engine light and reduced engine power message. Traction control is disabled when the check engine light is on but it's not a root cause/primary issue. Don't worry about the Cxxx codes until you fix the Pxxxx codes.
 
No. I went to auto zone. It's been fine all morning. Only seems to happen when I hit the gas pedal abnormally hard.. (not to say I'm flooring it) Just sort of slip of the foot
 
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Test the TPS if that's okay find someone with a real scan tool not a code reader to pinpoint the problem. You don't want to start throwing parts at it.
 
Thanks all !!

Just to confirm...as the lights all went away once.
Any chance it will fix itself? (caused by sitting)
 
I would clean the throttle body and intake and make sure all the linkages to the throttle body are lubed up. I have the same engine and they are prone to gumming and getting a bit of carbon in and around the throttle plate.
 
Originally Posted By: clarkflower
Thanks all !!

Just to confirm...as the lights all went away once.
Any chance it will fix itself? (caused by sitting)


It may, if it does it again and the TPS test good consider taking it to an independent for a scan, the will probably charge you
$50-75 but its worth it.
Nice car BTW, anything that has been sitting can have minor issues but they get worked out pretty quick once they are driven a bit.
 
I did test drive...and it didn't do it. But I didn't really hammer it as it was on a small dead end street with no plates and an old lady in the car. 90k car I paid 2700. No dents and all oil changes done. New AC.. Retail is 5200

As I said its fine in normal driving...Been driving all day
 
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Check the wiring to the ABS sensors, particularly the front. The copper metal-fatigues inside the insulation. I had a silhouette van (similar front suspension) snag that wire on the ball joint stud and get flaky.
 
Originally Posted By: Trav
Do you have a scan tool?

This may help in testing the TPS if you don't.

http://easyautodiagnostics.com/gm/3.8L/how-to-test-the-throttle-position-sensor-1


Part 2
6
If the TPS is good, the voltage reading on your multimeter will increase and stop at about 4.5 to 4.9 Volts DC (once the throttle is fully open).

7 Now, while still observing the multimeter's voltage readings, slowly close the throttle. The Voltage should decrease till it reaches the value you observed in test step 4.


That's what it says in your link. If you have a multimeter with a progress bar, why would you need a scan tool for checking the signal voltage?
 
*P1125 is APP Sensors 1 & 2 do not agree. Part of the throttle pedal assembly.
*P2138 is TPS Sensors 1 & 2 do not agree/outside predicted range, Part of the Throttle Body.

Charging system, Battery & connections in good shape?

*You need a way to read & clear trouble codes.
*Clean the throttle blade & bore.
*Key ON-Engine off, Cycle the throttle pedal several times to work the potentiometer contacts in the APPS & TB. Clear codes as they pop-up.
*If it still keeps throwing TPS correlation code/s.....Key Off, Manually move the throttle blade several times through it's entire range.

If a little old lady drove the car. It may have never been over 50% throttle?
 
Originally Posted By: das_peikko
Originally Posted By: Trav
Do you have a scan tool?

This may help in testing the TPS if you don't.

http://easyautodiagnostics.com/gm/3.8L/how-to-test-the-throttle-position-sensor-1


Part 2
6
If the TPS is good, the voltage reading on your multimeter will increase and stop at about 4.5 to 4.9 Volts DC (once the throttle is fully open).

7 Now, while still observing the multimeter's voltage readings, slowly close the throttle. The Voltage should decrease till it reaches the value you observed in test step 4.


That's what it says in your link. If you have a multimeter with a progress bar, why would you need a scan tool for checking the signal voltage?


For the TPS you don't but its easier, that why I posted the link. It can also read any other sensor values associated with the codes while they are in operation.
 
So I left this morning it ran fine all the lights but the check engine were off. Within 8 miles the check engine light went off
Throwing in some mobile one right now. I may try to get an inspection with the lights off now just to buy some time because it’s running great
 
thumbsup2.gif
Good to go.
 
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