DTC 53

Code 53 Chart:

Wiring Diagram For VATS Circuit:

*** UPDATED BY TSB #90-267-8A DATE: 5/90

CIRCUIT DESCRIPTION:

The VATS (Pass-Key) system is designed to disable vehicle operation if the incorrect key or starting procedure is used. The VATS decoder module sends a signal to the ECM if the correct key is being used. If the proper signal does not reach the ECM on circuit 229, the ECM will not pulse the injectors "ON" and will not allow the vehicle to start. A Code 53 will set if the proper signal is not received on circuit 229. A Code 53 is not stored in the ECM memory, but is only present when the above conditions exists.


TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. If the engine cranks, and a Code 53 is stored, it indicates that the portion of the module which generates the signal to the ECM is not operating, or circuit 229 is open or shorted to ground. If the decoder module is found to be OK, the ECM may be at fault, but this is an unlikely condition.

2. If the engine will not crank, this indicates that there is a VATS problem or an incorrect key or starting procedure is being used.


DIAGNOSTIC AIDS:

* = ECM fuse.