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 current passes through only some of the resistors. By "watching" the output voltage from CCM pin E11, the CCM determines which switch was pressed and performs the desired function.

If the CCM senses 5 volts (open) or more (short to B+) in CKT 1358 for more than 3 seconds, Code 13 is set.

Test Description

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

1. This test checks the voltage from CKT 1358 reaching the DIC switches circuit. If 0 volts, the circuit is open; if over 5.02 volts, the circuit has a short to B+; if 4.95-5.02 volts, the circuit is good up to that point.
2. This test checks to see if the CCM is at fault or if the circuit is open. If the reading is approximately 5 volts, CKT 1358 between the CCM and the switches is open; if the reading is 0 volts, either the connection to the CCM is bad or the CCM is faulty.
3. This test checks to see where the abnormally-high voltage is coming from. If voltage is measured, there is a short to B+ in CKT 1358; if no voltage is measured, there is an internal short in the CCM.
4. This test checks to see if the open is in the ground side (CKT 1383) or in the DIC switch assembly. If 0 volts is read, either CKT 1383 is open or its connection to the CCM is bad. 4.95-5.02 volts is read, CKT 1383 is good.
5. If the code displayed was a current fault (C13), the DIC switch assembly is open and should be replaced. If the code was a history fault (H13), the fault may be intermittent. See "Diagnostic Aids."

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, short, or an intermittent fault. Refer toRefer to "Intermittents/Poor Connections".

If pressing a DIC switch does not give the desired result but performs another DIC switch function or no function at all, it is possible that the DIC switches are internally open or shorted. If a switch is shorted to B+, pressing it will send the wrong signal to the CCM, since the voltage added to the circuit from the short will confuse the CCM. If a switch is open, pressing it will give no result at all. Use the Tech 1 to monitor the DIC key A/D counts while pressing the keys.