G 30 Van V8-454 7.4L VIN J SFI (1996)
Shift Interlock: Initial Inspection and Diagnostic Overview
Circuit Operation
The Brake Transmission Shift Interlock requires that the brake pedal be depressed before the automatic transmission may be shifted from Park position.
Once the transmission is placed in Park, and the Ignition Switch is in RUN or START, current flows from TURN B/U Fuse 16 through the
closed-in-Park contacts of the Park/Neutral Position Switch, through the TCC/Stoplamp Switch, and through the AT Shift Lock Solenoid to Ground
G201. The solenoid is energized preventing the transmission from being placed in another gear. When the brake pedal is depressed, the normally-closed
contacts in the TCC/Stoplamp Switch open. Current flow is stopped and the A/T Shift Lock Solenoid is de-energized. The transmission may be placed in
another gear. Once the transmission is in any other gear, the contacts in the Park/Neutral Position Switch are open and no current can flow to energize
the solenoid when the brake pedal is released.
Troubleshooting Hints - Brake Transaxle Shift Interlock
1. CHECK condition of TURN B/U Fuse 16. If fuse is open, LOCATE and REPAIR cause of overload and REPLACE fuse.
2. CHECK that Ground G201 is clean and tight.
^
CHECK for a broken (or partially broken) wire inside the insulation which could cause system malfunction but prove GOOD in a
Continuity/Voltage check with a system disconnected. These Circuits may be intermittent or resistive when loaded, and if possible, should be
checked by monitoring for a Voltage drop with the system operational (under load).
^
CHECK for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer to "General
Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
