Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

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Control Switch and Timer Test

The control switch and timer circuit may be tested in the vehicle with or without scan tool (DRB).

TESTING WITH SCAN TOOL
If using the scan tool, refer to the proper Body Diagnostic Procedures.

TESTING WITHOUT SCAN TOOL

HVAC Control Module Connectors:




1. Remove the control switch from console and disconnect control switch.

Control Module Test:




2. Using a ohmmeter, check leads between Pins 5 and 8 of the 8-Way connector. Turn the control module to each position shown on Control Module Test table. The resistance reading should be within the specifications shown. If not OK, replace the control module. If OK, check:
- Blown fuse
- Cut wire
- Poor ground
- Poor connection
- Defective BCM
- Bulkhead connector inoperative.