The headlight door circuit is a bit complicated because the door motors have to be able to stop automatically once the door reaches the full open position, and obviously, the same is true when the doors are fully closed. There are a couple of torque switches built into the motor case, with contacts just behind the brushes with a sliding slip collar between them. These contacts will open and close based on the shift of the motor armature and the sliding slip collar. When the headlight door opens, the armature and the sliding slip collar shifts back and forces the rear contact open. This works in the opposite manner when the headlight door closes (the sliding slip ring forces the front contact to open)
If the armature doesn't shift enough, because of broken gears (teeth missing), or if the sliding slip ring has been fractured, broken, or reassembled incorrectly, the contact will not open. If this contact doesn't open, the motor will continue to run (even with the headlight switch off), or until the internal circuit breaker opens and stops the motor. Even though you replaced all the correct parts, I'm not sure if the entire motor assembly, or just the motor itself, was replaced. If it was just the motor, I suspect the motor re-assembly is not correct.
As you see there can be a number of problems within the motor assembly that can cause the headlight door motor to malfunction. There are some parts, such as gears and motor rebuilds, available through Mid America Motorworks and Corvette Central.
Heart Transplant
I have an '85 Vette and have installed an '89 engine with its ECM. Now the car will not start, and I think the VATS are the problem. How can I disable it? I don't need anti-theft as I keep it in a garage and live in a small town. The GM dealership here has no idea what to do. I don't have original keys for the engine. Any info is much appreciated.Dennis, Creston, BC
When doing a transplant like this, there are several other items that may be keeping the vehicle from starting. There are many differences in relays and connectors that are not directly wired or related to the newer '89 ECM. You will likely need to make some wiring changes to your instrumentation, sensor relays, and, possibly, the sensors
You didn't mention if the starter was cranking, or if you had fuel pressure at the fuel rails. Both are related to the operation of the VATS (vehicle anti-theft system). For any car to start you must always have what I call FAST (fuel-air-spark-timing). Without all of these conditions the car will not start.
Fuel delivery is controlled by a fuel pump relay, which is controlled by the ECM. The VATS has an enable relay (Starter Enable Relay) that is needed to be satisfied by a special ignition key (Pass Key) before the ECM will allow the fuel pump to operate. This relay is found in the upper center console (above the radio). This same relay disables the starter circuit, which keeps the starter from cranking. To bypass the starter enable relay, locate the relay and place a jumper between the 10-gauge yellow wire and the 10-gauge green/white wire. This jumper, with the key on, should then provide 12-volt-plus to the clutch or neutral switch, and, finally, power to crank the starter. Once you turn the key on, the fuel pump will run for a couple seconds. If the car is not started, the pump will time out and shut off. To test fuel and pressure at the rails, you will need to turn the key on several times. Be sure you bleed the air from the system through the Schrader valve at the end of the fuel rail. With a fuel-pressure gauge, measure the fuel delivery pressure. This pressure should be greater than 48 psi. Finally, be sure the injectors have a good ground.