2003 CTS Problems

[jgabrielson]

Hi everyone,

I own a 03 CTS and just started having issues with it about a week ago. At randon while driving my T/C light will turn itself on but the engine seems to go into a reduced power mode, not allowing my to go more than 1,500 RPM's. I have to pull the car over and turn it off in order to br able to drive normal again. When I restart the car, I'm able to drive it normally again but eh check engine light will stay on for about a day or so, then seems to clear it self up. I noticed that the horn also doesnt work since it started. Does anyone have an y ideas on this or has had simliar issues?

Thanks

[Cadillac Jim]

This sounds like an electrical or wheel sensor problem. Run the OBD II codes and post them here and we can likelly get to the bottom of it all. Here's how:

http://www.caddyinfo.com/readingcodes.html

[BodybyFisher]

I may be wrong but I don't think the CTS is similar to the NS platform. I don't think you can pull the codes on it like we do. You might need a code reader capable of reading the CTS. I want to say that its an enhanced OBDII, with CAN? Bruce/Logan?

But yes, that is were I would start, the check engine light means that a diagnostic code was set and you need to find out what that code is, that will help you diagnose what the problem is

[Texas Jim]

I think Auto Zone can pull the codes for you. They do it for free.

[jgabrielson]

I was able to use the f1 & f6 key when I started to pull the codes. They are DTC P2135 and DTC B1327.

[Bruce Nunnally]

DTC P2135

Circuit Description

The throttle position (TP) sensors 1 and 2 are located within the throttle body assembly. The TP sensors share a common 5-volt reference circuit and a common low reference circuit. The 5-volt reference circuit is also shared with accelerator pedal position (APP) sensor 2. The 5-volt reference voltage is supplied on 2 separate engine control module (ECM) terminals, but the terminals are connected internally to the same voltage supply. Each TP sensor has an individual signal circuit, which provides the ECM with a signal voltage proportional to throttle the plate movement. When the throttle plate is in the closed position, the TP sensor 1 signal voltage is near the low reference and increases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. The ECM compares the signal of the throttle position sensors to the predicted TP sensor signal, based on calculations from the mass air flow (MAF) sensor. The control module also compares the signal of the TP sensor 1 and TP sensor 2 through the entire range. If the ECM detects a difference from the predicted range of more than 6 percent between sensor 1 and sensor 2, DTC P2135 sets.

Conditions for Running the DTC

* The battery voltage is more than 10 volts.

* The ignition is ON.

Conditions for Setting the DTC

The ECM detects that the difference between TP sensor 1 and TP sensor 2 is more than the predicted value.

Action Taken When the DTC Sets

* The control module stores the DTC information into memory when the diagnostic runs and fails.

* The malfunction indicator lamp (MIL) will not illuminate.

* The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.

* The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

* A current DTC Last Test Failed clears when the diagnostic runs and passes.

* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

* Clear the DTC with a scan tool.

DTC B1327

Circuit Description

The dash integration module (DIM) has an internal voltage sensor with a dedicated circuit that checks the battery positive voltage and battery negative circuit voltage to determine if it is above 9.0 volts.

Conditions for Running the DTC

This DTC shall run only if the DIM has power, ground and the ignition is not in START mode. This DTC shall execute regardless of the battery voltage, except when the DTC B1390 is set current.

Conditions for Setting the DTC

* This DTC shall be set as current when the voltage falls below 9.0 volts for 1200 milliseconds.

* When the vehicle exits START the DIM shall delay checking the voltage for 2 seconds.

Action Taken When the DTC Sets

A message shall be sent out on the class 2 lines to notify all other modules of low battery voltage.

Conditions for Clearing the MIL/DTC

In order to clear the DTC from a current status the voltage shall be greater than 9.54 volts for 1200 milliseconds.

[Texas Jim]

I was able to use the f1 & f6 key when I started to pull the codes. They are DTC P2135 and DTC B1327.

I think the DTS P2135 relates to the throttle position sensor. The actual position of the throttle is not the same as the COMMANDED position. It will go into a reduced power mode and turn on the light on the dash.

The DTC B1327 (I think) relates to a low voltage condition.

[Cadillac Jim]

The whole thing looks like a battery or battery cable problem to me. 'Tis the season.

[jgabrielson]

Morning,

After looking at the MAF, I noticed that it looks as if the cable has been cut and spliced back together somehow. It has about 6-7 cables and they look as if they have been cut or damaged by the serpentine belt on the motor in the past. I only noticed it because it had electrical tape rapped around 1/2 of the cable and the other half, near the block had that cable jacket that come with the car. When I unwrapped the tape, I noticed that the cables had been crimped and that the "new" cable was all the same color, unlike the OEM cable. I'm going to turn the car on this mornig and wiggle the cable to see if I can produce the same error. I would imagine that theres a short in one of the crimps or the acutal connector on the MAF itself. I'll keep you posted.