Test Notes

- A thermal fuse is built into the diagnostic monitor. If a short to ground should occur in the air bag deployment circuit, the microcomputer in the diagnostic monitor will send a signal to the fuse causing it to open. The open fuse removes all firing power (battery/backup power) from the deployment circuits. This prevents unwanted air bag deployments due to damaged vehicle wiring.
- Code 51 is displayed whenever the diagnostic monitor thermal fuse is open and no other higher priority faults exist (consult Fault Code Priority Table). Code 51 is normally seen after service of a Code 13 condition.
- If a Code 51 exists and a Code 13 condition has not been serviced, this means an intermittent short-to-ground exists in the air bag deployment wiring. The intermittent short-to-ground must be located and serviced before servicing the Code 51 condition.
- Since the thermal fuse is built into the diagnostic monitor, the monitor must be replaced to service a Code 51 condition. NEVER replace the diagnostic monitor without first determining the cause for the Code 51 condition. If the short-to-ground is not properly serviced, the short may reoccur, once again destroying the thermal fuse in the diagnostic monitor.