SMU - Revised DTC P1125
| Subject: | Revised DTC P1125 |
| Models: | 2003 Cadillac Escalade, Escalade ESV, Escalade EXT |
| 2003 Chevrolet Avalanche, Kodiak, Silverado, Suburban, Tahoe, TrailBlazer, TrailBlazer EXT, W Series Medium Duty Tilt Cab |
| 2003 GMC Envoy, Envoy XL, Sierra, Sierra Denali, TopKick, W Series Medium Duty Tilt Cab, Yukon, Yukon Denali, Yukon Denali XL, Yukon XL |
| 2003 HUMMER H2 |
| with 4.8L, 5.3L, 6.0L or 8.1L Engine (VINs V, P, T, U, N, G -- RPOs LR4, LM4, LM7, LQ4, LQ9, L18) |
This bulletin is being issued to revise DTC P1125 in the Engine Controls sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.
The following information has been updated within SI. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.
Circuit Description
The accelerator pedal position (APP) sensor 1 and APP sensor 2 are potentiometer type sensors, each with the following circuits:
| • | A 5-volt reference circuit |
| • | A low reference circuit |
| • | A signal circuit |
The control module provides the APP sensors a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. APP sensor 2 signal voltage is near the reference voltage at rest and decreases as the pedal is depressed. When the control module detects that the APP sensor 1 and the APP sensor 2 signal circuits are out of correlation with each other, DTC P1125 sets.
Conditions for Running the DTC
| • | DTC P2108 is not set. |
| • | The ignition is in the crank or run position. |
| • | The ignition voltage is more than 5.23 volts. |
| • | The communication between the TAC module and the powertrain control module (PCM) must be valid. |
Conditions for Setting the DTC
The PCM detects that the difference between APP sensor 1 and APP sensor 2 is more than the predicted value.
Diagnostic Aids
| • | Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing. |
| • | The APP sensor 1 and the throttle position (TP) sensor 1, 5-volt reference circuits are internally connected within the TAC module. |
| • | The APP sensor 2 and the TP sensor 2, 5-volt reference circuits are internally connected within the TAC module. |
| • | When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Remember this if you review the information stored in Captured Info. |
| • | For an intermittent, refer to Intermittent Conditions . |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views | ||||||||||
1 |
Important: This DTC indicates that two or more accelerator pedal position (APP) sensor DTCs are also set. Diagnose the APP sensor DTCs that are set. Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls | ||||||
2 | Record the throttle actuator control (TAC) module calibration with a scan tool Does the TAC module calibration match the part number of the TAC module? | -- | Go to Step 3 | Go to Step 11 | ||||||
3 | Observe the DTC Information with a scan tool. Is DTC P2120 or P2125 also set? | -- | Go to Diagnostic Trouble Code (DTC) List | Go to Step 4 | ||||||
4 |
Does the scan tool indicate that the APP sensors 1 and 2 parameter disagrees? | -- | Go to Step 5 | Go to Diagnostic Aids | ||||||
5 |
Is the resistance more than the specified value for any circuit? | 5ohms | Go to Step 9 | Go to Step 6 | ||||||
6 | Test the signal circuit of the APP sensor 1 for a short to the signal circuit of the APP sensor 2. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | ||||||
7 | Test for an intermittent and for a poor connection at the TAC module. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 | ||||||
8 | Test for an intermittent and for a poor connection at the APP sensor. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||||
9 | Repair the high resistance in the circuit that measured above the specified value. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | -- | ||||||
10 | Replace the APP sensor. Refer to Accelerator Pedal Position (APP) Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
11 | Replace the TAC module. Refer to Throttle Actuator Control (TAC) Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||
12 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 | ||||||
13 |
Important: Be aware that repairing one individual condition may correct more than one DTC. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List | System OK | ||||||
