Module Controlled Functions

The Remote Anti-theft Personality (RAP) module controls the perimeter anti-theft, the keyless entry, and computer operated locks systems.

The Generic Electronic Module (GEM) is equipped on four-wheel drive (control trac system) or two-wheel drive vehicles with power windows. The Central Timer Module (CTM) is equipped only on the two-wheel drive vehicles without power windows.

NOTE: GEM/CTM diagnostics are compatible with New Generation STAR (NGS) Tester.

The GEM/CTM incorporates the functions of several different modules into one and offers diagnostics to easily locate and repair concerns affecting the subsystems that it controls.

The GEM/CTM constantly monitors the systems under its control and reports a concern in the form of a Diagnostic Trouble Code (DTC). A DTC can be retrieved with NGS Tester through the communication link.

NGS Tester is a menu-driven tester that allows the user to run specific diagnostic tests. It can isolate faults in the GEM/CTM subsystems through a symptom-driven diagnostic procedure. Connecting NGS Tester to the GEM/CTM communication link will not alert the GEM/CTM. If the GEM/CTM is in sleep mode when the diagnostic connector is plugged in, the GEM/CTM must be activated. If the communication link cannot be established, it will advise to turn the ignition to RUN.

The GEM/CTM control system has two modes of operation, the normal operating mode and the tester dependent diagnostics mode.

NOTE: The GEM/CTM can only detect open circuit/short to ground (GND) faults when the GEM/CTM is not energizing a load, and short to battery faults when the GEM/CTM is attempting to energize a load.

The normal operation of the GEM/CTM can detect errors. An integral part of the normal GEM/CTM operation is the continuous diagnostic capability. Continuous diagnostics detects errors and changes the GEM/CTM control strategy. There is no warning light for the GEM/CTM; therefore, a DTC concern will direct the technician to the GEM/CTM. Examples of faults, that may be detected during normal operation include:
- GEM/CTM continuous self-test (RAM, ROM, EEPROM, AID checking).
- Output driver monitoring (open circuit/short to GND, short to battery).
- Illogical combinations of input signals.