Test Notes

NORMAL OPERATION
The normal voltage on Pins C277-2, C277-6, C277-17 and C277-18 is controlled by an internal resistor inside the air bag diagnostic monitor and is internally regulated to approximately 10 volts (± 1 volt). The resistance to ground from these pins in the air bag diagnostic monitor harness connector must be infinite. The resistance across the normally open contacts of the two primary crash sensors must also be infinite. The air bag diagnostic monitor measures the voltage on Pins C277-2, C277-6, C277-17 and C277-18. If there is any resistance to ground on any of these pins or across the primary crash sensor contacts, it will cause the diagnostic voltage on these pins to drop below normal levels. If the air bag diagnostic monitor measures that this voltage has dropped to between 5 and 10 volts, the air bag diagnostic monitor senses it has an internal voltage regulator failure and will flash Diagnostic Trouble Code (DTC) 53. Note that a direct short to ground in the primary crash sensor circuits will drop the voltage to less than 5 volts and the air bag diagnostic monitor will flash DTC 14 on the air bag indicator; refer to DTC 14 for additional information.

The air bag diagnostic monitor also performs several on-board diagnostics every time the ignition switch is turned to RUN. If any of these tests fail, the air bag diagnostic monitor will flash DTC 53 on the air bag indicator.

POSSIBLE CAUSES
A voltage drop in the primary crash sensor circuits or an internal air bag diagnostic monitor failure can be caused by:
1. A partial drop in voltage in the primary crash sensor circuits due to resistance to ground on the primary crash sensor wiring or any resistance across the normally open primary crash sensor contacts.
2. Internal air bag diagnostic monitor on-board diagnostic failure.