Express 3/4 Ton Van V8-5.7L VIN R (1998)
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 the TURN B/U Fuse 16 through the contacts of
the Park/Neutral Position Switch (closed-in-Park). through the TCC/Stoplamp Switch, and through the A/T 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 the condition of the TURN B/U Fuse 16. If the fuse is open, LOCATE and REPAIR the cause of the overload and REPLACE the 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).
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CHECK for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer Troubleshooting
Procedures). See: Diagrams/Diagnostic Aids