Using J 42958 Tester

Diagnostic Aids
In order to avoid misdiagnosis:
- Inspect for proper operation of the brake lamps
- Visually inspect all fuses relative to the cruise control system. Inspect all connectors for poor terminal retention, corrosion or damage.
- Inspect the throttle linkage/cable for mechanical binding.
- Inspect cruise control cable adjustment.
- EMI on the speed sensor signal circuit may cause erratic operation.

PCM Inhibit
The PCM will inhibit (not allow) cruise control if one or more of the following has occurred:
- Park, reverse, neutral, or first gear is indicated by the Park/Neutral switch.
- Certain Diagnostic Trouble Codes (DTC) are stored. Refer to the appropriate DTC(s).
- An over/undercharged battery condition exists.
- Engine RPM is low.
- Engine RPM is high (Fuel Cut-Off).

The Cruise Control Tester
When this Tester is used on some vehicles with high resistance or an open in the cruise control module ground circuit, the Tester's LED(s) will light abnormally. For example, the Brake/Clutch and VSS LED(s) will light normally but the Ignition LED will be dim with the ON/OFF switch in the OFF position. However, with the ON/OFF switch in the ON position only the VSS LED will light. If the above situation occurs, please check the ground circuit before continuing with your diagnosis.

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