B0936

DTC B0936





Circuit Description
When the engine coolant is at the proper level in the surge tank, the low coolant level switch is closed. When in this condition, battery voltage is applied to the low coolant level signal circuit of the body control module (BCM). When coolant is below the proper level, the low coolant level switch opens. Because no voltage is applied to the low coolant level signal circuit, the BCM responds by sending a serial data message to the instrument panel cluster to turn on the low coolant level light. The BCM has an internal timer, which will not turn on the low coolant level light unless the coolant level is low for longer than 30 seconds. The timer avoids falsely turning on the light due to the movement of coolant within the surge tank.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B0936 Coolant Level Sensor Circuit

Conditions for Running the DTC
^ Ignition switch in RUN or Crank position.
^ Low coolant warning light always On with the ignition in Start.
^ IGN 1 fuse in underhood fuse block is open.

Conditions for Setting the DTC
^ The condition exists for longer then 30 seconds.
^ The coolant level switch signal short to voltage or open.
^ The coolant level switch signal short to ground.

Action Taken When the DTC Sets
B0936 - The BCM detects a short to ground or an open on the coolant level signal circuit.

Conditions for Clearing the DTC
^ The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ Use the scan tool Clear DTC Information function.

Diagnostic Aids
^ Check for poor connection at the BCM.
^ Check for poor connection at the low coolant level switch.
^ If the fault is suspected to be intermittent refer to Testing for Intermittent Conditions and Poor Connections.

Test Description





The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies the normal status of the signal circuit to the BCM.
3. This step tests for voltage at the coolant level switch. The IGN 1 fuse supplies power to the voltage side of the coolant level switch.
4. This step verifies that the BCM is providing ground to the coolant.