B3788

B3788 - Blower Motor Relay Control Circuit High

Schematic:

CIRCUIT DESCRIPTION
The body control module (BCM) provides ground through circuit 247 (retailer installed accessory) to enable the after blow relay operation, the relay is located in the instrument panel fuse block (IPFB). Circuit 247 and the after blow relay are retailer installed. The BCM provides the logic to enable blower motor based on information from the engine control module (ECM). The duration on the after blow is determined by A/C operation, ambient air temperature and vehicle speed.

DTC PARAMETERS
^ Output = On
^ Short to battery continuously for 5 seconds in circuit 247.
^ No light will illuminate in I/P.

DIAGNOSTIC AIDS
^ 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 insulation and not conductors).
^ Inspect wiring harness for damage. Check for broken or chafed 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.

TEST

Diagnostic Chart: