Probable Causes
The probable root causes are listed in order below:
• Intermittent Diagnostic Codes
• Burned out bulb
• Problem with Lamp circuit (Vehicle)
• The Lamp does not come on.
• Short in Set/Resume Switch Circuit
• Short in Vehicle Harness
Recommended Actions
Perform the following diagnostic procedures in order:
1. Check for logged diagnostic codes and active diagnostic codes with an Electronic Service Tool.
2. In order to check the Check Engine Lamp, turn the ignition key to the ON position while the engine is OFF.
The Check Engine Lamp should turn on. Then, the Check Engine Lamp should turn off. The Check Engine Lamp will flash if there is an Active Diagnostic Code.
a. If the Check Engine Lamp does not operate correctly remove the Check Engine Lamp (terminal 28) from the ECM connector (seventy terminal).
b. Connect the Check Engine Lamp (terminal 28) to the Ground Stud. Turn the ignition key switch to the ON position.
c. Observe the Check Engine Lamp.
If the Check Engine Lamp comes on, check the power connection and the ground connection of the ECM. Refer to Troubleshooting, “Check Engine Lamp Circuit – Test” for additional information.
If the lamp does not come on, check the lamp in order to ensure that the lamp is not burned out. Also, check the wiring in order to ensure that there is not an open circuit.
3. In order to check the Warning Lamp, start the engine.
The Warning Lamp should come on for at least 2 seconds. Then, the Warning Lamp should turn off. The Warning Lamp will remain on or flash if there is a problem with the engine.
a. If the Warning Lamp does not operate correctly remove the Warning Lamp (terminal 29) from the ECM connector (seventy terminal).
b. Connect the Warning Lamp (terminal 29) to the Ground Stud. Turn the ignition key switch to the ON position.
c. Observe the Warning Lamp.
If the Warning Lamp comes on, check the power connection and the ground connection of the ECM. Refer to Troubleshooting, “Warning Lamp Circuit – Test” for additional information.
If the lamp does not come on, check the lamp in order to ensure that the lamp is not burned out. Also, check the wiring in order to ensure that there is not an open circuit.
4. Connect an Electronic Service Tool. Observe the status screen for the Cruise Control Set/Resume Switch.
If the status screen indicates that the switch is ON and the switch is not in the ON position, the switch is shorted out. Refer to Troubleshooting, “Cruise Control Switch Circuit – Test”.
5. Monitor the Check Engine Lamp while the Check Engine Lamp (terminal 28) is removed from the ECM connector (seventy terminal). Also, the technician could monitor the Check Engine Lamp while the ECM Connector (P1) is disconnected.
If the lamp remains on and the pin has been removed from the ECM, there is a short circuit to ground in the vehicle harness.
6. Monitor the Warning Lamp while the Warning Lamp (terminal 29) is removed from the ECM connector (seventy terminal). Also, the technician could monitor the Warning Lamp while the ECM
Connector (P1) is disconnected.
If the lamp remains on and the pin has been removed from the ECM, there is a short circuit to ground in the vehicle harness.
