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 locks, door ajar switches); the CCM grounds CKT 690, energizing the relay coil.

Code 25 will set when CKT 690 is NOT at battery voltage for over 600 milliseconds while the CCM is NOT attempting to actuate the courtesy lamp relay (not asking for courtesy lamps "ON").

Test Description

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

1. This test checks for an open or short to ground in CKT 840. (Also see the description for Test 6).
2. This test checks for an internal open in the relay.
3. This test checks for an internal short in the relay which would cause a short to ground.
4. This test checks for an open or short to ground in CKT 690 by telling the CCM to cycle the ground at pin D12 "ON" and "OFF." The test lamp should cycle "ON" and "OFF"; if it does not, or stays on continuously, a problem is indicated.
5. This test determines whether an open indicated in Test 4 lies in the wiring or connection to CKT 690 or in the CCM itself.
6. This test determines if a problem in CKT 840 found in Test 1 is an open or short to ground.

Diagnostic Aids

If the code is a history code, the problem may be intermittent. Try performing the test shown while "wiggling" wiring and connectors; this can often cause the fault to appear. Check for poor connections at both 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 ground, the courtesy lamps will be "ON" at all times. If CKT 690 is open, the courtesy lamp will be "OFF" at all times.