The test switch terminal is located in the duty check data link connector behind the glovebox. The PCM sets the ignition timing to the base setting when the test switch terminal is grounded.
• | The engine is running at a steady speed. |
• | The engine operating in Close Loop. |
• | The vehicle speed is above 2 km/h (1 mph). |
• | The test switch is ON. |
• | The condition is present for 5 seconds |
• | The PCM illuminates the malfunction indicator lamp (MIL). |
• | The PCM records the operating conditions at the time that the diagnostic fails. The Freeze Frame buffer stores this information. |
• | The PCM turns OFF the MIL after three consecutive trips, during which the diagnostic runs and a fault is not detected. |
• | A History DTC clears after 40 consecutive warm-up cycles without a fault. |
• | Use the Clear DTC Information function on the scan tool in order to clear the DTC information. |
Check for a damaged wiring harness. Inspect the wiring harness for damage that may cause a short to ground. With the engine running, wiggle the wiring harness to the duty check data link connector. Use the scan tool in order to read the test switch status for the Spark Advance Adjust parameter. An ON display on the scan tool indicates that the harness is shorting to ground.
The numbers below refer to the step numbers in the diagnostic table.
The Powertrain OBD System Check prompts the technician to complete some basic checks, and to save the applicable Freeze Frame data on the scan tool. This creates an electronic copy of the data that was taken when the fault occurred. The scan tool saves the information for later reference.
This step determines if a fault is present.
This step checks for a short to ground on the test switch terminal and on the circuitry. If there is a short to ground in the test switch signal circuit, the ignition timing will be held at the base timing.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | |||
Does the scan tool indicate the Spark Advance Adjust parameter is ON? | -- | Go to Diagnostic Aids | ||
Is the voltage near the specified value? | 5 V | Go to Diagnostic Aids | ||
4 |
Was a repair necessary? | -- | ||
5 | Replace the PCM. Is the action complete? | -- | -- | |
6 |
Does the scan tool display any DTCs? | -- | Go to the applicable DTC table | System OK |