1, 2 and 3 Digit Codes: 29

CODE NUMBER
Scan tool: 29
General scan tool: P0120

CODE NAME
Throttle position signal

CODE DESCRIPTION
Technical Description
The Transmission Control Module (TCM) receives the throttle position from the Throttle Position Sensor (TPS). The TIPS has a 5-volt pull up supplied from the Powertrain Control Module (PCM). The signal is checked for out of range as well as intermittents (excessive signal changes).

Check Area
Monitored whenever the engine is running. The following conditions must be sensor out put and TCM open or short-circuited met for a successful OBDII trip:
- The engine must run for more than two minutes.
- The turbine speed must be greater than 600 r/min or the output speed must be greater than 400 r/min.
- If the transmission is below normal operating temperature, all forward gears must be applied for 3.5 seconds each and the transmission must be in either "park" or "neutral" for 3.5 seconds.
- If the transmission is hot, all forward gears must be applied for 1.5 seconds each and the transmission must be in either "park" or "neutral" for 1.5 seconds.
- No MIL lamp trouble codes have occurred or reoccurred.

Set Conditions
This code is set if the throttle angle goes out of range or if throttle angle changes abruptly. (i.e., faster than the throttle body motion could occur)

Transmission Effects
Extremely erratic transmission shifting with an intermittent TPS signal just prior to setting the code. If the intermittents does not last long enough to set the code, the customer will say that the transmission violently hunts between gears. If this code is set, the TCM uses a "calculated throttle angle" supplied by the PCM over the CCD bus. If this CCD bus is unavailable, the TCM uses a default throttle angle of 24 degrees for the key start 0 which the code was set. The TCM will try to use the TIPS signal again on the next key start.

PROBABLE CAUSE
- Malfunction of the throttle position sensor
- Harness or connector between throttle position sensor and TCM open or short-circuited
- Malfunction of TCM
- Malfunction of PCM





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