Central Control Module (CCM)

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The Liquid Crystal Display (LCD) blanking control circuit carries a signal which allows all segments of the LCD to be turned "OFF" simultaneously; its purpose is to allow the CCM to blank the LCD panel with a single signal.

DTC 26 will set when CKT 1374 is at a high state for over 600 milliseconds while the CCM is requesting the circuit to be low.

TEST DESCRIPTION

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

1. This test checks for a good signal to the instrument cluster from the CCM.

2. This test replaces the cluster with a 1200 ohm resistance, very similar to the resistance of the cluster. If the DTC comes back, the CCM must be at fault. If the DTC does not come back, the cluster must be the source of the problem.

3. This test checks for another DTC being set. If that DTC was set, it is possible that the problems which set that DTC also set this one.

DIAGNOSTIC AIDS

If this fault is present, the LCD portion of the instrument cluster will be blank.

If the DTC is a history DTC, the problem may be intermittent. Try performing the tests shown while "wiggling" wiring and connectors; this can often cause the malfunction to appear. Refer to "Intermittents and Poor Connections" in DIAGRAMS.