N: LFC 14/DTC B1901 - Front External Crash Sensor Sht to Gnd

Normal Operation
The front external crash sensors monitor the severity of a crash event. If the crash event is severe enough, the sensor(s) will close and signal the Restraints Control Module (RCM) to deploy the air bags. Each front external crash sensor contains a 1580 ohm resistor. The two crash sensors are connected in parallel at the splice in circuit 619 (PK/WH). Because of the parallel connection, the RCM normally measures about 790 ohms to ground on circuit 619 (PK/WH).

The RCM measures this resistance to verify that the crash sensors are correctly mounted and connected. If there is a short to ground on circuit 619 (PK/WH), the RCM will store Diagnostic Trouble Code (DTC) B1901 in memory. The RCM will also flash Lamp Fault Code (LFC) 14 (or higher priority code if one exists) on the air bag indicator.

Possible Causes
A front external crash sensor shorted to ground fault can be caused by:
- a short to ground on circuit 619 (PK/WH).
- a damaged or inoperative front external crash sensor.
- an RCM internal concern.

Pinpoint Test Steps:

N1:

N2 - N3:

N4 - N5:

N6: