Powertrain Controls - ECM/PCM

Cruise Servo Circuit Diagram:

Code 62 Diagnostic Chart:

CIRCUIT DESCRIPTION:

The cruise switch within the turn signal lever receives ignition voltage from a 15 amp fuse through CKT 639 to the turn signal lever cruise switches. The cruise on/off, set/coast, and resume/accel switches are inputs to the cruise control portion of the PCM.
The cruise servo vent and vac solenoids are the output lines and are controlled by high side drivers in the PCM. When the ignition is "ON", the PCM looks at these output lines and will set codes depending on the status of each line.

OPERATION
The cruise vacuum solenoid is a normally closed solenoid that blocks the flow of vacuum to the cruise servo when de-energized ("OFF"). When the solenoid is energized ("ON"), it opens, allowing engine vacuum to be applied to the servo.

Code 62 will set if:

^ A short to voltage on CKT 402 occurs, energizing the solenoid when the PCM is commanding the solenoid "OFF" (de-energized).
^ CKT 402 is open.
^ CKT 402 is shorted to ground when the PCM is commanding the vac solenoid "ON".
^ One of the above conditions are met for more than 0.5 seconds.

DIAGNOSTIC AIDS:
An intermittent may be caused by a poor connection, worn through wire insulation, or a wire broken inside the insulation. Check for:
^ Poor connection or damaged harness. Inspect harness connectors for backed out terminals, improper mating, broken locks, bad terminals, poor terminal to wire connections, and damaged harness.