Circuit Description
The left rear wheel speed sensor provides a signal to the electronic brake and traction control module (EBTCM). In addition to wheel speed information, the signal from the left rear wheel speed sensor provides the only input for vehicle speed information. The EBTCM sends out a vehicle speed signal based on the information from this sensor. The vehicle speed signal is sent to the theft deterrent module and to all other modules requiring vehicle speed information. The vehicle speed signal to the theft deterrent module is then sent to the engine control module (ECM) on the same circuit used to communicate the theft deterrent information.
Conditions for Running the DTC
| • | The decel fuel cut-off is enabled. |
| • | The engine speed is between 1,800-2,200 RPM. |
| • | The engine coolant temperature (ECT) is more than 65°C (149°F). |
Conditions for Setting the DTC
The vehicle speed sensor (VSS) is less than 20 km/h (12 mph) for longer than 1 second.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems for intermittent concerns.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If a DTC P1502 is set, the vehicle will not start or may start and stall. DTC P1502 indicates the condition causing the DTC P0500 is located in the circuit between the theft deterrent module and the ECM.
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This step is to determine if the EBTCM is capable of producing a vehicle speed signal.
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This step is to determine if the vehicle speed signal is available at the theft deterrent module.
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This step is to determine if the theft deterrent module is causing the loss of the vehicle speed signal.
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This step is to isolate each of the modules connected to the vehicle speed signal circuit to determine if any of the modules are causing the loss of the signal. This step also prepares the vehicle for the next two steps by having all of the components on the signal circuit disconnected in order to test for a short to ground or a short to voltage.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
With a scan tool, review the engine control module (ECM) DTC information. Is a DTC P1502 set? | -- | Go to DTC P1502 | Go to Step 3 | |||||||
Does the speedometer indicate a vehicle speed above the specified value? | 0 km/h (0 mph) | Go to Step 6 | Go to Step 4 | |||||||
4 |
Did you find and repair a concern with the EBTCM system? | -- | Go to Step 17 | Go to Step 5 | ||||||
5 |
Did you find and repair an open circuit? | -- | Go to Step 17 | Go to Step 7 | ||||||
Does the DMM indicate a frequency above the specified value? | 10 Hz | Go to Step 12 | Go to Step 13 | |||||||
Does the speedometer indicate a vehicle speed above the specified value? | 0 km/h (0 mph) | Go to Step 16 | Go to Step 8 | |||||||
Important: Do not disconnect the EBTCM connector for this test. Turn OFF the ignition before disconnecting each module.
Does the DMM indicate a frequency above the specified value after disconnecting any of the modules? | 10 Hz | Go to Step 14 | Go to Step 9 | |||||||
9 |
Did you find and repair a short to ground? | -- | Go to Step 17 | Go to Step 10 | ||||||
10 |
Did you find and repair a short to voltage? | -- | Go to Step 17 | Go to Step 11 | ||||||
11 | Test for poor connections/terminal tension at the EBTCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct a problem? | -- | Go to Step 17 | Go to Step 15 | ||||||
12 | Test for poor connections/terminal tension at the theft deterrent module harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct a problem? | -- | Go to Step 17 | Go to Step 16 | ||||||
13 | Repair the open vehicle speed signal circuit between splice 222 and the theft deterrent module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 17 | -- | ||||||
14 | Replace the most recently disconnected module. Refer to the appropriate repair instructions for module replacement. Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||
15 | Replace the EBTCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System. Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||
16 | Replace the theft deterrent module. Refer to Theft Deterrent Module Replacement in Theft Deterrent. Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||
17 |
Does the DTC run and pass? | -- | Go to Step 18 | Go to Step 2 | ||||||
18 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
