Test Description
The numbers below refer to the step numbers in the diagnostic table.
- 2: This step determines if a communication condition exists.
- 5: This step isolates an internal APP sensor failure. The condition may only occur at a certain accelerator pedal position. Monitoring the APP angles for sensor 2 and sensor 3 is an accurate way of verifying the actual position of the pedal. The APP angles for all 3 sensors should be within a few percent of each other. If the pedal is at rest, the APP angle for all 3 sensors should be 0 percent. If the pedal is fully depressed, all APP angles should be 100 percent.
- 6: The APP sensor 1 shares a common 5-volt reference circuit with the throttle position (TP) sensor 1. Monitoring the TP sensor 1 voltage aids in diagnosing the APP sensor 5-volt reference and low-reference circuits. If the scan tool displays near 0 volts, the circuits are OK.
- 9: With the TAC module still connected, this test will help determine a short to the signal circuit either within the TAC module or wiring.
- 10: This step determines whether the TAC module or a shorted circuit is causing the condition.
- 19: When the TAC module detects a condition within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
DTC P2121
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | - | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Is DTC U0107 also set? | - | Go to DTC U0107 | Go to Step 3 |
| 3 |
IMPORTANT:
Do not depress the accelerator pedal.
|
- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 4 |
| 4 | Observe the APP Sensor Agree/Disagree parameters with a scan tool. Does the scan tool indicate Disagree for any of the APP Agree/Disagree parameters? |
- | Go to Step 6 | Go to Step 5 |
| 5 |
|
- | Go to Diagnostic Aids | Go to Step 6 |
| 6 |
|
0.0 V | Go to Step 7 | Go to Step 11 |
| 7 |
|
0.0 V | Go to Step 8 | Go to Step 12 |
| 8 |
|
5.0 V | Go to Step 14 | Go to Step 9 |
| 9 | Test for a short between the APP sensor 1 signal circuit and all other APP circuits at the APP sensor harness connector with a DMM. Does the DMM indicate a short to another circuit? |
- | Go to Step 10 | Go to Step 13 |
| 10 |
|
- | Go to Step 18 | Go to Step 15 |
| 11 |
|
- | Go to Step 18 | Go to Step 15 |
| 12 |
|
- | Go to Step 18 | Go to Step 15 |
| 13 |
|
- | Go to Step 18 | Go to Step 15 |
| 14 | Inspect for poor connections at the harness connector of the APP sensor. Refer to Testing for Intermittent Conditions and Poor Connections
and Repairing Connector Terminals
. Did you find and correct the condition? |
- | Go to Step 18 | Go to Step 16 |
| 15 | Inspect for poor connections at the harness connectors of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections
and Repairing Connector Terminals
. Did you find and correct the condition? |
- | Go to Step 18 | Go to Step 17 |
| 16 | Replace the APP sensor assembly. Refer to Accelerator Pedal with Position Sensor Replacement
. Did you complete the replacement? |
- | Go to Step 18 | - |
| 17 | Replace the TAC module. Refer to Control Module References
for replacement, setup, and programming. Did you complete the replacement? |
- | Go to Step 18 | - |
| 18 |
|
- | Go to Step 2 | Go to Step 19 |
| 19 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? |
- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK |