Code 53, Vehicle Anti-Theft System: Notes

The Vehicle Anti-Theft System (VATS) is designed to disable vehicle operation if an incorrect ignition key or starting procedure is used. The anti-theft decoder module sends a signal to the ECM if the correct key is used. If the proper signal does not reach the ECM on circuit No. 229, the ECM will not pulse the injectors and the vehicle will not start. Code 53 will set.

1. If the engine cranks and a Code 53 is stored, it indicates the VATS decoder module, which generates the signal to the ECM, is not operating or circuit No. 229 is open or shorted to ground. If VATS decoder module is okay, the ECM may be at fault, but this is not likely.
2. If Code 53 is stored and the engine will not start, it indicates an anti-theft system problem, an incorrect ignition key or starting procedure is used.