Test Notes

Normal Operation
The air bag diagnostic monitor measures the voltage at pins C20a-2, circuit 7-MA30 (YE/UN) and C20a-6, circuit 7-MA28 (YE/RD) of the air bag diagnostic monitor connector. The voltage at these pins varies with the charging system voltage as shown in the table:




Air Bag Diagnostic Monitor Typical Pin Voltages With System Connected and Engine Running

If the air bag diagnostic monitor measures a voltage of less than five volts on either of these pins, the air bag diagnostic monitor will flash Diagnostic Trouble Code (DTC) 14 on the air bag indicator to indicate a possible short to ground on these circuits. When flashing DTC 14, the air bag diagnostic monitor blows its internal thermal fuse. This disables the air bag deployment circuit. If the voltage at pin C20a-2, circuit 7-MA30 (YE/GN) or pin C20a-6, circuit 7-MA28 (YE/RD) returns to normal (because the short to ground no longer exists), DTC 51 will be flashed on the air bag indicator, due to the open thermal fuse. (Refer to Pinpoint Test O, Normal Operation O: LFC/DTC 51 - Diag Mon Int Thermal Fuse Due to Intermit Short).

Possible Causes
Low voltage at air bag diagnostic monitor pins C20a-2, C20a-17, C20a-18, or C20a-6 can be caused by:
1. A short to ground on circuits 31S-MA26 (BK/RD), 31S-MA25 (BK/GN), 7-MA30 (YE/UN), or 7-MA28 (YE/RD), causing the diagnostic voltage to drop.
2. An internal short to ground within either of the crash sensors.