GM/Detroit 6.5L – COOLANT LEVEL INDICATOR DIAGNOSIS

DIESEL ENGINES
The coolant level indicator circuit is shown in figure 7.

Indicator Lamp Will Not Illuminate
1. Turn the ignition switch to the “ON” position.
• If the lamp illuminates, the lamp is OK and the connector is properly installed on the module. Go to step 2.
• If the lamp does not illuminate, check the bulb, socket, and wiring between the socket and the module connector, as well as the connector on the module. Replace or repair as required.
2. Turn the ignition switch to the “ON” position and disconnect the electrical lead at the coolant level sensor on the radiator.
• If the lamp fails to illuminate, check the wiring between the coolant level sensor connector and the module for a short circuit to ground. If the cir­cuit is OK, replace the module.

Indicator Lamp Remains Illuminated
1. Turn the ignition switch to the “ON” position.
• Check the coolant level. Add coolant if neces­sary.
• If the lamp remains illuminated, go to step 2.
2. Disconnect the electrical lead at the coolant level sensor on the surge tank and use a jumper wire and “G” type electrical connector.
• If the lamp does not illuminate, replace the sen­sor.
• If the lamp remains illuminated, connect the electrical lead and go to step 3.
3. Check for an open circuit between the sensor and the module.
• If an open circuit is found, repair it.
• If no open circuit is found, replace the module.