P1628

P1628-SENSOR REFERENCE VOLTAGE 2 CIRCUIT ERRATIC





For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
Ignition on.

- Set Condition:
When the Powertrain Control Module (PCM) recognizes the (F856) 5-Volt Supply circuit voltage is varying too much to quickly. One Trip Fault. ETC light is flashing.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

NOTE: Improperly installed aftermarket accessories can cause this DTC to set. Check for any improperly installed aftermarket accessories before continuing with this test.

1. CHECK FOR AN INTERMITTENT CONNECTION IN THE ENGINE WIRING HARNESS





NOTE: Diagnose any active or pending Sensor Reference High or Sensor Reference Low DTCs before proceeding with this test procedure. If this DTC is present without an active or pending Sensor Reference High or Sensor Reference Low DTC, the most likely cause is an intermittent open or short circuit in the wiring harness between the engine and the PCM.

1. Turn the ignition off.
2. Disconnect the MAP Sensor harness connector.
3. Connect a Voltmeter to the (F856) 5-Volt Supply circuit at the MAP Sensor harness connector.

NOTE: Make sure that there is a good positive connection between the Voltmeter lead and the MAP Sensor harness connector terminal since we are looking for an intermittent connection.

4. Turn the ignition on.
5. While monitoring the voltage reading on the Voltmeter, wiggle test the entire engine wiring harness all the way to the PCM.

NOTE: Look for any quick changes in the Voltmeter reading. The Voltmeter should read steady 5 Volts +/-.01 or.02 Volts with the Throttle Body Assembly harness connector unplugged.

Did the Voltmeter reading change from 5 Volts at any time while wiggle testing the wiring?

Yes

- Repair the (F855) 5-Volt Supply circuit for an intermittent open or short circuit in the wiring harness. Make sure to check all of the in-line connectors for poor connections or spread terminals.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 2

2. CHECK FOR AN INTERMITTENT CONNECTION IN THE APP WIRING HARNESS




1. Turn the ignition off.
2. Disconnect the APP Sensor harness connector.
3. Connect a Voltmeter to the (K854) 5-Volt Supply circuit at the APP Sensor harness connector.
4. Turn the ignition on.
5. While monitoring the voltage reading on the Voltmeter, wiggle test the wiring harness between the APP Sensor and the PCM.

Did the Voltmeter reading change from 5 Volts at any time while wiggle testing the wiring?

Yes

- Repair the (K854) 5-Volt Supply circuit for an intermittent open or short circuit in the wiring harness. Make sure to check all of the in-line connectors for poor connections or spread terminals.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the related sensors and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related Sensor and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.