Important: This DTC is also used for the inflatable restraint electronic frontal sensor (EFS) found on the 35/36 series trucks. The 35/36 series trucks have one EFS located at the front of the vehicle. The EFS is diagnosed the same way as the inflatable restraint side impact sensor (SIS) used on Utility models. The following diagnostics will refer to the left SIS or the EFS depending on what series truck you are diagnosing.

The SIS/EFS circuit consists of a SIS/EFS, the SIS/EFS signal circuit, and the SIS/EFS voltage circuit. When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM provides input power to the SIS/EFS. When input power is first detected, the SIS/EFS responds by performing internal diagnostics. The SIS/EFS then sends an ID message to the SDM. The SDM will consider this to be a valid ID if the response time is less than 5 seconds after the SIS/EFS is powered up. The SIS/EFS will continually communicate a status message to the SDM. The SDM is capable of resetting the SIS/EFS by removing and applying power to it.

Ignition 1 voltage is within the normal operating voltage range.

The SDM has received a NOK (not OK) message from the left SIS/EFS.

The SDM commands ON the AIR BAG indicator via Class 2 serial data.

The following number refers to the step number in the diagnostic table:

2. Tests the communication status of the left SIS/EFS.