P2138
P2138-ACCELERATOR PEDAL POSITION SENSOR 1/2 CORRELATION
For a complete wiring diagram refer to: Electrical Diagrams
When Monitored
With the ignition on and no APPS No. 1 and APPS No.2 DTC present.
Set Condition
APPS values No.1 and No.2 are not coherent. Idle is additionally forced when the brake pedal is pressed or failed. Acceleration rate and Engine output are limited. One trip fault and the code will set within 5 seconds. ETC light is flashing.
Possible Causes
- EXCESSIVE RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT
- EXCESSIVE RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT
- EXCESSIVE RESISTANCE IN THE (K167) SENSOR NO.1 RETURN CIRCUIT
- EXCESSIVE RESISTANCE IN THE (K400) SENSOR NO.2 RETURN CIRCUIT
- EXCESSIVE RESISTANCE IN THE (K23) APP SENSOR NO.1 SIGNAL CIRCUIT
- EXCESSIVE RESISTANCE IN THE (K29) APP SENSOR NO.2 SIGNAL CIRCUIT
- APP SENSOR
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
NOTE: Repair any other 5-Volt Supply or APPS High and Low DTCs before diagnosing P2138.
Is the DTC active at this time?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. EXCESSIVE RESISTANCE IN THE (K23) APPS NO.1 SIGNAL CIRCUIT
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Turn the ignition off.
Disconnect the APP Sensor harness connector. Disconnect the PCM harness connector.
Measure the resistance of (K23) APP Sensor No.1 Signal circuit from the APP Sensor harness connector to the appropriate terminals of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 3
No >> Repair the excessive resistance in the (K23) APP Sensor No.1 Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. EXCESSIVE RESISTANCE IN THE (K29) APPS NO.2 SIGNAL CIRCUIT
Measure the resistance of (K29) APPS No.2 Signal circuit from the APP Sensor harness connector to the appropriate terminals of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 4
No >> Repair the excessive resistance in the (K29) APP Sensor No.2 Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. EXCESSIVE RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT
Measure the resistance of the (F855) 5-volt Supply circuit from the APP Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance above 5.0 ohms?
Yes >> Repair the excessive resistance in the (F855) 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 5
5. EXCESSIVE RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT
Disconnect the C1/A PCM harness connector.
Measure the resistance of the (F856) 5-volt Supply circuit from the APP Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance above 5.0 ohms?
Yes >> Repair the excessive resistance in the (F856) 5-volt Supply circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 6
6. EXCESSIVE RESISTANCE IN THE (K167) SENSOR NO.1 RETURN CIRCUIT
Measure the resistance of the (K167) APP Sensor No.1 Return circuit from the APP Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance above 5.0 ohms?
Yes >> Repair the excessive resistance in the (K1 67) Sensor No. 1 Return circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 7
7. EXCESSIVE RESISTANCE IN THE (K400) SENSOR NO.2 RETURN CIRCUIT
Measure the resistance of the (K400) APP Sensor No.2 Return circuit from the APP Sensor harness connector to the appropriate terminal special tool #8815.
Is the resistance above 5.0 ohms?
Yes >> Repair the excessive resistance in the (K400) Sensor No.2 Return circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 8
8. CHECKING APPS NO.1 AND NO.2 WITH A LAB SCOPE
Ignition on, engine not running.
Set up a lab scope in a way that you can view two graphs simultaneously.
Backprobe (K23) APP Sensor No.1 Signal circuit using Channel 1 at the APP Sensor harness connector.
Backprobe (K29) APP Sensor No.2 Signal circuit using Channel 2 at the APP Sensor harness connector.
Slowly press and release the Accelerator Pedal while monitoring the lab scope screen.
Does the scope pattern show any missing or erratic signals?
Yes >> Replace the APP Sensor Assembly per Service Information. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values. Go To 9
No >> Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
9. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes >> Repair as necessary
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test