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2003 CTS Transmission problem


Benny

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Hi fellow Cadillac enthusiasts,

I'm looking for help on behalf of another member of the Cadillac Club Sweden. He's the owner of a 2003 CTS.

When he hits the brake the transmission acts very strange and strikes the different positions very roughly. High idle speed has also occurred. :huh:(English is not my mother tongue but I hope this description is understandable)

The MIL lamp turns on and a message Reduced engine power is shown on the DIC.

The dealership over here in Stockholm has so far had serious problems to correct the malfunction. They have replaced the PCM a couple of times but the problems return after a short time. The Cadillac model is very unusual in Sweden and thus they don't have much experience to rest on.

The DTC:s identified are:

DTC P0121: TP Sensor Circuit Insufficient Activity

DTC P0221: Throttle Position (TP) Sensor 2 Performance

DTC P0507: Incorrect Idle Speed

DTC P0700: Transmission Control Module (TCM) Requested MIL Illumination

DTC P2135: Throttle Position (TP) Sensor 1-2 Correlation

DTC P2176: Minimum Throttle Position Not Learned

Any help is appreciated.

Thank you very much in advance,

Bengt Olsson B)

Moderator sub forum Cadillac Club Sweden

Bengt Olsson

Cadillac Club Sweden

99 STS Vogue Gold Edition

Corsa cat-back w gold tips

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The throttle (the accelerator pedal) has TWO sensors that it uses to give instructions to the engine control computer.

They are like rheostats and the two signals HAVE TO MATCH, or the engine computer does not know how much gas to give it.

P0121: TP Sensor Circuit Insufficient Activity

One of the sensors is not sending sufficient signal.

P0221: Throttle Position (TP) Sensor 2 Performance

Probably this one...number 2.

P2135: Throttle Position (TP) Sensor 1-2 Correlation

The two signals DON'T MATCH...

This is when you get the "REDUCED POWER" message. :D

The engine computer don't know what it is supposed to do, so it goes into limp mode.

P0507: Incorrect Idle Speed

Thus giving it incorrect idle speed...

P0700: Transmission Control Module (TCM) Requested MIL Illumination

And then turning on the Service Light

I think I am right, but there area lot of people here that know a lot more than I do.

They will correct me if I am wrong. :D:D:D

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I looked on the GM site. I do not see any TSB's jumping out at me. It sounds like there are 2 TPS sensors. One could be at the gas pedal. But it appears the 2 are out of sync.

That said. Most GM codes you start at the lowest code for diagnostics. Start at code 100, then code 200.

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Thank you very much both of you.

Texas Jim's analysis seems to me very logical and trustworthy. I have forwarded the information to the Cadillac service facility and our member. Hopefully the service guys will act accordingly and our member will have his car back working properly soon again.

Thanks again,

/Bengt Olsson B)

Bengt Olsson

Cadillac Club Sweden

99 STS Vogue Gold Edition

Corsa cat-back w gold tips

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