DTC 37

Circuit Description

The M Clock Circuit carries a square wave signal which provides alternating voltage to the LCD's backplane; this is required for proper operation of the LCD.

Upon power-up, the CCM pulls CKT 1366 low. If it is high during the next 80 milliseconds, Code 37 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 the CCM is internally open, some segments of the digits in the display will be "ON" and some will be "OFF"; some segments of the digits will be dim, and others will be full-brightness.

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".