Central Control Module (CCM)

Circuit Description

The LCD Data Circuit carries the actual 160-bit data stream that contains the desired states of all segments on the LCD panel.

Code 31 will set if CKT 1365 is not in a low state 80 milliseconds after CCM power-up.

Test Description

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

1. This test check 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 code comes back, the CCM must be at fault. If the code does not come back, the cluster must be the source of the problem.
3. This test checks for another code being set. If that code was set, it is possible that the problems which set that code also set this one.

Diagnostic Aids

If the circuit is shorted to B+ or the CCM is internally open, the LCD will be blank.

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. Refer to "Intermittents/Poor Connections".