P0501
P0501-VEHICLE SPEED SENSOR 1 PERFORMANCETheory of Operation
The vehicle speed sensor rationality is a continuous test that monitors the vehicle speed sensor for lack of activity. The rationality will not run if a limp-in exists for MAP, Throttle Position, and Engine Coolant Temperature. If vehicle speed sensor is below a minimum threshold for a period of time after the vehicle is operated at a sufficient load, a failure will be indicated.
WHEN MONITORED
With the engine running, transmission not in park or neutral, brakes not applied, and engine rpm greater than 1500.
SET CONDITION
This code will set if no vehicle speed signal is received from the ABS Module up to 120 seconds for 2 consecutive trips. Two Trip Fault. Three good trips to turn off the MIL.
POSSIBLE CAUSES
- (B22) Vehicle speed signal open
- (B22) Vehicle speed signal short to ground
- Tire circumference
- 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.
Q: Is the DTC active at this time?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Component Tests and General Diagnostics
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. VISUAL INSPECTION
NOTE: This code can set due to tire circumference differences and from the front or rear wheels being on a slippery surface while the opposite tires are not. This code may also set on a hard acceleration on loose gravel or during other off road driving conditions.
Check tire pressure of all the tires.
Check tire wear on all the tires.
Ask the customer what the road and driving conditions were like when the fault set.
Q: Were any problems found?
YES: Repair as necessary. If the code set during a front OR rear wheel spin condition, no repair is necessary.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 3
3. (B22) VEHICLE SPEED SIGNAL CIRCUIT OPEN
Disconnect the C1 BCM harness connector.
Disconnect the C1 PCM harness connector.
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.
Measure the resistance of the (B22) Vehicle Speed Sensor Signal circuit from the C1 BCM harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance above 5.0 ohms?
YES: Repair the open in the (B22) Vehicle Speed Sensor Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 4
4. (B22) VEHICLE SPEED SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (B22) Vehicle Speed Sensor Signal circuit connector at the appropriate terminal of special tool #8815.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (B22) Vehicle Speed Sensor Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 5
5. (F512) VEHICLE SPEED SENSOR SUPPLY CIRCUIT OPEN
Disconnect the C2 BCM harness connector.
Disconnect the Vehicle Speed Sensor harness connector.
Measure the resistance of the (F512) Vehicle Speed Sensor Supply circuit from the Vehicle Speed Sensor harness connector to the C2 BCM harness connector.
Q: Is the resistance above 5.0 ohms?
YES: Repair the open in the (F512) Vehicle Speed Sensor Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 6
6. (F512) VEHICLE SPEED SENSOR SUPPLY CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (F512) Vehicle Speed Sensor Supply circuit at the Vehicle Speed Sensor harness connector.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (F512) Vehicle Speed Sensor Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 7
7. (B12) VEHICLE SPEED SENSOR SIGNAL CIRCUIT OPEN
Measure the resistance of the (B12) Vehicle Speed Sensor Signal circuit from the Vehicle Speed Sensor harness connector to the C2 BCM harness connector.
Q: Is the resistance above 5.0 ohms?
YES: Repair the open in the (B12) Vehicle Speed Sensor Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 8
8. (B12) VEHICLE SPEED SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (B12) Vehicle Speed Sensor Signal circuit at the Vehicle Speed Sensor harness connector.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (B12) Vehicle Speed Sensor Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 9
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.
Q: 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