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

TEST DESCRIPTION

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

1. This test checks for a short to ground in the circuit.

2. This test checks for an open in the circuit.

3. 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.

DIAGNOSTIC AIDS


If the circuit is open, the LCD display will be blank; if there is a short to ground, the display will not update (will be "frozen").

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.