P2123

P2123-PPS 1 VOLTAGE TOO HIGH

P2123 - PPS 1 Voltage Too High:

WHEN MONITORED
While the key is on and during engine operation.

SET CONDITION
The APPS signal circuit voltage at the ECM goes above 4.24 volts for more than 2 seconds.

POSSIBLE CAUSES
- (K167) APPS no. 1 return circuit open
- (K23) APPS no. 1 signal circuit shorted to (K852) APPS NO. 1 5-volt supply
- (K23) APPS signal circuit shorted to another circuit
- ECM
- APPS
- Intermittent condition

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. (K167) APPS NO. 1 RETURN CIRCUIT OPEN





Turn the ignition off.
Disconnect the APPS harness connector.
Disconnect the ECM harness connectors.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance on the (K167) APPS No. 1 return circuit between the sensor harness connector and the ECM harness connector.

Q: Is the resistance less than 10 ohms?

YES: Go To 2
NO: Repair the (K167) APPS No. 1 return circuit open. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

2. (K23) APPS NO. 1 SIGNAL CIRCUIT SHORTED TO (K852) APPS NO. 1 5-VOLT SUPPLY





Measure the resistance between the (K23) APPS No. 1 signal circuit in the sensor harness connector and the (K852) APPS No. 1 5-volt supply circuit in the sensor harness connector.

Q: Is the resistance greater than 100 K ohms?

YES: Go To 3
NO: Repair the (K23) APPS No. 1 signal circuit shorted to the (K852) 5-volt supply circuit. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

3. (K23) APPS SIGNAL CIRCUIT SHORTED TO ANOTHER CIRCUIT





Measure the resistance between the APPS No. 1 signal circuit at the ECM harness connector and all other circuits in the ECM harness connector.

Q: Is the resistance greater than 100 k ohms?

YES: Go To 4
NO: Repair the (K23) APPS No. 1 signal circuit shorted to another circuit in the engine harness. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

4. ECM
Reconnect the ECM harness connectors.
Reconnect the APPS harness connector.
While monitoring with the scan tool, disconnect the sensor connector.

Q: Did a APPS No. 1 and APPS No. 2 voltage too low DTC set?

YES: Go To 5
NO: Replace and program the ECM in accordance with the Service Information. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

5. APPS
Reconnect the APPS harness connector.
Monitor the APPS No. 1 and APPS No. 2 voltage with the scan tool while depressing the throttle pedal.

Q: Is the voltage transition shown on the scan tool smooth while depressing the throttle and is the voltage from APPS 1 twice as much as from APPS2?

YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
NO: Replace the APPS. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1