P2127
P2127-PPS 2 VOLTAGE TOO LOWP2127 - PPS 2 Voltage Too Low:
WHEN MONITORED
While the key is on and during engine operation.
SET CONDITION
The APPS circuit voltage at the ECM goes below 0.13 volt for more than 2 seconds.
POSSIBLE CAUSES
- APPS
- ECM
- (K29) APPS No. 2 signal circuit open
- (F856) APPS No. 2 5-volt supply open
- (K29) APPS No. 2 signal circuit shorted to ground
- (K29) APPS No. 2 signal circuit shorted to other circuits
- (F856) APPS No. 2 5-volt supply circuit shorted to ground
- (F856) APPS No. 2 5-volt supply circuit shorted to other circuits
- Intermittent condition
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. (K29) APPS NO. 2 SIGNAL CIRCUIT OPEN
Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the APPS harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the (K29) APPS No. 2 signal circuit between the APPS sensor harness connector and the ECM harness connector.
Q: Is the resistance less than 10 ohms?
YES: Go To 2
NO: Repair the (K29) APPS No. 2 signal circuit open. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
2. (F856) APPS NO. 2 5-VOLT SUPPLY OPEN
Measure the resistance of the (F856) APPS No. 2 5-volt supply circuit between the APPS sensor harness connector and the ECM harness connector.
Q: Is the resistance less than 10 ohms?
YES: Go To 3
NO: Repair the (F856) APPS No. 2 5-volt supply open. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
3. (K29) APPS NO. 2 SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between the (K29) APPS No. 2 signal circuit at the sensor harness connector and battery negative.
Q: Is the resistance greater than 100 k ohms?
YES: Go To 4
NO: Repair the (K29) APPS No. 2 signal circuit shorted to ground. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
4. (K29) APPS NO. 2 SIGNAL CIRCUIT SHORTED TO OTHER CIRCUITS
Measure the resistance between the (K29) APPS No. 2 signal circuit at the ECM harness connector and all other circuits in the ECM harness connectors.
Q: Is the resistance greater than 100 k ohms?
YES: Go To 5
NO: Repair the (K29) APPS No. 2 signal circuit shorted to other circuits. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
5. (F856) APPS NO. 2 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
Measure the resistance between the (F856) APPS No. 2 5-volt supply circuit at the sensor harness connector and battery negative.
Q: Is the resistance greater than 100 k ohms?
YES: Go To 6
NO: Repair the (F856) APPS No. 2 5-volt supply circuit shorted to ground. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
6. (F856) APPS NO. 2 5-VOLT SUPPLY CIRCUIT SHORTED TO OTHER CIRCUITS
Measure the resistance between the (F856) APPS No. 2 5-volt supply circuit at the sensor harness connector and all other circuits in the ECM harness connector.
Q: Is the resistance greater than 100 k ohms?
YES: Go To 7
NO: Repair the (F856) APPS No. 2 5-volt supply circuit shorted to other circuits. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
7. ECM
Reconnect the ECM harness connectors.
Turn the ignition on.
While monitoring with the scan tool, connect a jumper wire between the (K29) APPS No. 2 signal circuit at the sensor harness connector and the (F856) APPS No. 2 5-volt supply circuit at the sensor harness connector.
NOTE: With the sensor disconnected it is normal to have a APPS 1 and APPS 2 low voltage DTC set.
Q: Did DTC P2128 set?
YES: Go To 8
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
8. APPS
Reconnect the APPS harness connector.
Monitor the APPS 1 and APPS 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 swing smooth?
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