Operation CHARM: Car repair manuals for everyone.

B0936










CIRCUIT DESCRIPTION
When engine coolant is at the proper level, the low coolant switch is closed. When in this condition, battery voltage is applied to the low coolant 1478 input of the body control module (BCM).
When coolant is below the proper level, the coolant switch opens. Because no voltage is applied to circuit 1478, the BCM responds by sending a serial data message to the instrument panel cluster to turn "On" the "low coolant" telltale.
The BCM has an internal timer, which will not turn "On" the low coolant telltale unless the coolant level is low for greater than 30 seconds. The timer avoids coolant "sloshing" falsely turning "On" the "low coolant" telltale.

DTC PARAMETERS
^ Ignition in "RUN" position.
^ Low coolant condition (No voltage on circuit 1478 for greater than 30 seconds)

DTC PARAMETERS
^ Check for poor connection at BCM. Inspect harness connector for backed out terminals, improper terminal mating, broken connector locks, improperly formed or damaged terminals and poor terminal to wire connection (terminal crimped over wire isolation and not conductors).
^ Inspect wiring harness for damage. Check for broken or chaffed insulation.
^ Check for poor connection at the low coolant switch.
^ If fault is suspected to be intermittent, wiggling harness wiring may help in locating fault.