110 RENR5042-02 Troubleshooting Section Expected Result: Repair: Replace the ECM. Refer to Troubleshooting, “Replacing the ECM”. Verify that the original problem is resolved. The voltage between terminals A (+8 V digital supply) and B (sensor return) is 8.0 ± 0.4 VDC. STOP. Results: OK – The supply voltage is reaching the sensor. i02289836 Diagnostic Lamp Circuit - Test Repair: Replace the engine coolant level sensor. Verify that the original problem is resolved. SMCS Code: 7431-038-NQ STOP. System Operation Description: Not OK The supply voltage is not reaching the sensor. The diagnostic lamp is used to inform the operator of active diagnostic codes and active event codes. Repair:
Refer to Troubleshooting, “Digital Sensor Supply Circuit - Test” for the appropriate troubleshooting procedure. The Electronic Control Module (ECM) provides a path to ground for the diagnostic lamp. When the ECM connects the diagnostic lamp to ground the diagnostic lamp will turn on. STOP. Test Step 5. Create a Short Circuit at the ECM P1 Connector A. Remove terminals P1-3 and P1-49. Install a jumper wire into open terminals P1-3 and P1-49. B. Turn the keyswitch to the ON position and monitor the status of “Coolant Level” on Cat ET while the jumper wire is installed. C. Remove the jumper wire. Monitor the status of “Coolant Level” on Cat ET. D. Turn the keyswitch to the OFF position.
Expected Result: The status of the switch is “OK” when the jumper wire is connected. The status of the switch is “Low” when the jumper wire is not connected. g01123371 Illustration 37 Results: Schematic for the diagnostic lamp OK The status of the switch is when the jumper wire is connected. The status of the switch is when the jumper wire is not connected. The ECM is properly reading the switch input. However, the ECM did not detect the jumper wire at the sensor connector. There is a problem with the wiring. There may be a problem with a connector. Test Step 1. Check the Operation of the Diagnostic Lamp A. Turn the keyswitch to the ON position. B. Monitor the diagnostic lamp.
Expected Result: Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the original problem is resolved. The diagnostic lamp turns on for five seconds. Then, the diagnostic lamp turns off. If a diagnostic code is active, the diagnostic lamp will flash. STOP. Not OK – The ECM is not reading the switch input.