Central Control Module (CCM)

Circuit Description

The courtesy lamp relay coil circuit is completed by the CCM when it receives a courtesy lamps "ON" request from any of a number of different inputs (door lock switches, door ajar switches); the CCM grounds CKT 690, energizing the relay coil.

Code 24 will set when CKT 690 is in a high state (not grounded by the CCM) for more than 600 milliseconds while the CCM is attempting to activate the courtesy lamp control relay.

Test Description

Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test checks for a short to B+ in CKT 690.
2. This test checks for an internal short to B+ in the relay.
3. This test checks for an internal open in the relay.
4. This test checks for proper CCM control of the circuit by telling the CCM to cycle the ground at terminal "2" "ON" and "OFF." If the connection at the CCM, the wiring and the relay connector are good but the test light does not cycle "ON" and "OFF," the CCM is faulty and should be replaced.

Diagnostic Aids

If the code is a history code, the problem may be intermittent. Try performing the tests shown while "wiggling" wiring and connectors; this can often cause the fault to appear. Check for poor connections at the CCM and the courtesy lamp relay connector; these could cause an open or an intermittent fault. Refer to "Intermittents/Poor Connections".

If CKT 690 is shorted to battery, the courtesy and cargo area lamps will not come "ON" as intended.