Central Control Module (CCM)

Circuit Description

The Data Clock Circuit provides the timing signal which causes each of the 160 bits of the LCD data signal to be clocked into the buffer of the LCD display.

Upon power-up, the CCM pulls CKT 1367 low. If the circuit is not low after 80 milliseconds, Code 33 will set.

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 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 there is a short to B+ or the CCM is internally open, the cluster display will be random characters, and the display will be "frozen."

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".