P0501

P0501-VEHICLE SPEED SENSOR 1 PERFORMANCE





For complete wiring diagrams refer to Diagrams/Electrical.


- When Monitored:

While the engine is running.

- Set Condition:

The ECM indicates signals of motion; however, the VSS does not.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. VEHICLE SPEED SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE

Turn the ignition off.

Disconnect the ECM harness connectors.

Disconnect the ABS/RWAL Module harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Ignition on, engine not running.

Measure the voltage of the Vehicle Speed signal circuit in the ABS/RWAL or ECM harness connector.

Is the voltage above 4.9 volts?

Yes

- Repair the short to voltage in the Vehicle Speed Signal circuit between the CAB and ECM.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 2

2. VEHICLE SPEED SENSOR SIGNAL CIRCUIT OPEN BETWEEN CAB AND ECM

Turn the ignition off.

Measure the resistance of the Vehicle Speed signal circuit between the ECM harness connector and the ABS/RWAL harness connector.

Is the resistance above 5.0 ohms?

Yes

- Repair the open in the Vehicle Speed signal circuit between the CAB and ECM.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 3

3. VEHICLE SPEED SENSOR SIGNAL CIRCUIT SHORT TO GROUND

Measure the resistance between ground and the Vehicle Speed signal circuit at the ECM harness connector.

Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the Vehicle Speed signal circuit between the CAB and ECM.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 4

4. ECM


NOTE: Before continuing, check the ECM 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.

If there are no possible causes remaining, view repair.

Repair

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