Fuel - Reduced Power, Various DTCs May Be Present
File In Section: 06 - Engine/Propulsion SystemBulletin No.: 99-06-04-039
Date: September, 1999
TECHNICAL
Subject:
Reduced Engine Power, DTC(s) P1125, P1275, P1276, P1280, P1281, P1285, and/or P1286 May be Present [Current or in History]
(Replace Accelerator Pedal Assembly)
Models:
1999 Chevrolet and GMC B7 Models
with 7.4L Engine (VINs B, D - RPOs L21, LP4)
1999 Chevrolet and GMC G2-3 Van Models
with 6.5L Diesel Engine (VIN F - RPO L65)
Condition
Some owners/operators may comment about reduced engine power. During this condition, the REDUCED ENGINE POWER lamp/message illuminates and powertrain control module (PCM) Diagnostic Trouble Codes (DTC) for the throttle actuator control (TAC) system are set. Cycling the ignition key to the "OFF" position for 15 seconds or more will reset the PCM allowing normal engine operation until the condition recurs.
The DTCs set will be for the accelerator pedal position (APP) sensor and may consist of one or more of the following DTCs: P1125, P1275, P1276, P1280, P1281, P1285 or P1286.
Cause
An incorrect signal from the APP sensor may cause this condition. The TAC module monitors three sensor inputs generated from the APP sensor. If one of these inputs is incorrect, the TAC module will default the PCM to control the engine in a reduced power mode. This reduced power mode will only allow a maximum throttle angle of approximately 16 percent.
Correction
Replace the accelerator pedal assembly, which includes the APP sensor, on affected vehicles. Use the following procedure and the appropriate part number listed below.
Accelerator Pedal and Bracket Assembly (B Models)
Accelerator Pedal and Bracket Assembly (G Van Models)
Notice:
Handle the electronic throttle control components carefully. Use cleanliness in order to prevent damage. Do not drop the electronic throttle control components. Do not roughly handle the electronic throttle control components. Do not immerse the electronic throttle control components in cleaning solvents of any type.
1. Disconnect the APP sensor module (1) electrical connector.
2. Remove the accelerator pedal bracket mounting bolts/nuts.
3. Remove the accelerator pedal and bracket assembly from the cowl (2).
4. Install the new accelerator pedal and bracket assembly to the cowl.
5. Install the accelerator pedal bracket mounting bolts/nuts.
Tighten
Tighten the accelerator mounting bolts/nuts to 12-14 Nm (106-124 lb in).
6. Connect the APP sensor module electrical connector.
7. Use the Tech 2 or disconnect the battery in order to clear all stored codes.
Parts Information
Part Number Description Qty
15984422 Pedal Asm., Accel. w/Throttle
Position Sensor 1
(B Models w/L21, LP4)
15153811 Pedal, Accel. w/Bracket
(G Van w/L65) 1
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Description Labor Time
J5350 Pedal, Accelerator - Replace Use published
Labor operation time