Central Control Module (CCM)

Circuit Description

The Driver Information Center (DIC) switches circuit contains a number of resistors. When a particular switch is pressed, this selects a specific resistance value since the circuit voltage passes through only some of the resistors. By "watching" the output voltage from CCM pin E11, the CCM knows which switch was pressed and performs the desired function.

If the CCM senses less resistance in CKT 1358 than would be seen through the driver information center switches resistors for more than 3 seconds, a short to ground is indicated and Code 14 is set.

Test Description

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

1. This test checks for a short to ground in CKT 1358 from the CCM to the DIC switch assembly. If the voltage measured is 4.95-5.02 volts, the CCM and connections and wiring up to the DIC assembly are good; if the code was a current fault (C14), the DIC switches are faulty and should be replaced. If the voltage measured is less than 4.95 volts, the short to ground is either in CKT 1358, the DIC switches, or the CCM.
2. This test checks to see if the short to ground is in the CKT 1358 wire itself.
3. This test checks to see if the problem is in the DIC switches.

Diagnostic Aids

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. Check for poor connections at both the CCM and the DIC assembly; these could cause an open or an intermittent fault. Refer to "Intermittents/History Codes/Poor Connections".

If pressing a DIC switch does not give the desired result, but performs another DIC switch function, it is possible that the DIC switches are internally shorted. If a switch is shorted, pressing it would send the wrong signal to the CCM, since the internal short would bypass some of the resistors needed to produce the correct switch signal. Use the Tech 1 to monitor the DIC key AID counts while pressing the keys.