Central Control Module (CCM)

Circuit Description

When a CCM is replaced, it must be programmed to accept the resistance value of the existing vehicle keys to allow PASS-Key(R) operation. The CCM prompts the technician to insert two of the three keys in succession. The CCM compares the resistances of each of the keys inserted and, if they are both within the same resistance "window," the programming sequence ends and the PASS-Key(R) system is ready for operation.

The PASS-Key(R) detection circuit is completed by the PASS-Key(R) (with embedded resistor pellet) in the ignition lock cylinder. Contacts in the ignition lock cylinder mate with those on the pellet, and the CCM reads the key pellet resistance.

Code 61 will set if the CCM senses that the key # 1 resistance is out of the allowed range of PASS-Key(R) resistance values.

Test Description

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

1. This test checks to see if the PASS-Key(R) resistor pellet is within the allowable range of PASS-Key(R) resistances.
2. This test checks if the CCM output and CKT 1073's wiring and connectors are good up to the ignition lock cylinder connector.
3. This test checks if the CCM internal ground and CKT 1074's wiring and connectors are good up to the ignition lock cylinder connector.
4. This test quick-checks the wiring lock cylinder and key assembly for resistance within the PASS-Key(R) range.
5. This test checks to see if a problem indicated in Test # 2 lies in the CKT 1073 wiring or connectors or in the CCM itself.

Diagnostic Aids

Check for poor connections at both the CCM and the ignition lock cylinder connector; these could cause an open, short, incorrect PASS-Key(R) resistance, or an intermittent fault. Refer to "Intermittents/Poor Connections".

Make sure the key resistor contacts are clean and free of any grease, oil, etc. These substances could interfere with the key detection circuit and set a code.

Before replacing a CCM due to a PASS-Key(R) code, make sure the key resistor is clean, clear the CCM codes, and try the programming sequence again. If the code resets and the problem is not found in the code chart, replace the CCM.

If the code is a history code, the PASS-Key(R) programming sequence was never successfully completed. This will also be indicated by a flashing "SECURITY" lamp whenever the ignition is "ON."