Ford Mustang (1999-2004) Service Manual: Pinpoint Test K: LFC 35/DTC B1935 - Passenger Air Bag Circuit Resistance Low

Normal Operation

The restraints control module (RCM) monitors the resistance of the passenger air bag ignitor by measuring the resistance between pins 6 and 7. If the RCM detects low resistance between these pins, it will store a diagnostic trouble code (DTC) B1935 in memory and flash a lamp fault code (LFC) 35 (or higher priority code if one exists) on the air bag indicator.

Possible Causes

Passenger air bag low resistance can be caused by:

a short in the wiring harness.
a low resistance in the passenger air bag module.
an RCM internal concern.
a worn or damaged connector shorting bar or camming beam.

PINPOINT TEST K: LFC 35/DTC B1935 - PASSENGER AIR BAG CIRCUIT RESISTANCE LOW

Test Step	Result / Action to Take
K1 CHECK FOR A HARD OR INTERMITTENT DTC	Yes This is a hard fault. The fault condition is still present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test. GO to K2 . No This is an intermittent fault. The fault condition is not present at this time. GO to K4 .
Key in OFF position. Connect the diagnostic tool. Scan Tool Key in ON position. Enter the following diagnostic mode on the diagnostic tool: Retrieve/Clear Continuous DTCs. Retrieve and record any continuous DTCs for use later in this pinpoint test. Enter the following diagnostic mode on the diagnostic tool: On- Demand Self Test. Was DTC B1935 retrieved during the on-demand self test?
K2 CHECK THE PASSENGER AIR BAG MODULE	Yes GO to K3 . No INSTALL a new passenger air bag module. GO to K5 .
WARNING: If the supplemental restraint system (SRS) is being serviced, the system must be deactivated and restraint system diagnostic tools must be installed. Refer to Air Bag Supplemental Restraint System (SRS) in this section. The air bag restraint system diagnostic tools must be removed and the air bag modules reconnected when the system is reactivated to avoid non-deployment in a collision, resulting in possible personal injury. NOTE: Diagnostics or repairs are not to be performed on a seat equipped with a seat side air bag with the seat in the vehicle. Prior to attempting to diagnose or repair a seat concern when equipped with a seat side air bag, the seat must be removed from the vehicle and the restraint system diagnostic tools must be installed in the seat side air bag electrical connectors. The restraint system diagnostic tools must be removed prior to operating the vehicle over the road. NOTE: After diagnosing or repairing an SRS, the restraint system diagnostic tools must be removed before operating the vehicle over the road. NOTE: After diagnosing or repairing a seat system, the restraint system diagnostic tools must be removed before operating the vehicle over the road. NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer. Key in OFF position. Deactivate the system. Refer to Air Bag Supplemental Restraint System (SRS) in the Diagnosis and Testing portion of this section. Key in OFF position. Key in ON position. Enter the following diagnostic mode on the diagnostic tool: On- Demand Self Test. Was DTC B1935 retrieved?
K3 CHECK THE PASSENGER AIR BAG MODULE CIRCUIT	Yes INSTALL a new RCM. GO to K5 . No REPAIR the circuit (s) as necessary. GO to K5 .
Key in OFF position. Disconnect: Passenger Air Bag Restraint System Diagnostic Tool. Measure the resistance between passenger air bag C256, circuit 607 (LB/OG), harness side and passenger air bag C256, circuit 616 (PK/BK), harness side. Is the resistance greater than 10,000 ohm?
K4 CHECK FOR AN INTERMITTENT FAULT	Yes CHECK for causes of intermittent low resistance on circuit 607 (LB/OG) and circuit 616 (PK/BK). Attempt to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. GO to K5 . No GO to K5 .
Refer to the continuous DTCs recorded during Step K1. Was the continuous DTC retrieved during Step K1 an intermittent fault?
K5 CHECK FOR ADDITIONAL DTCs	Yes Do not clear any DTCs until all DTCs have been resolved. GO to the Restraints Control Module (RCM) Diagnostic Trouble Code (DTC) Priority Table in this section for pinpoint test direction. No RECONNECT the system. REACTIVATE the system. PROVE OUT the system. REFER to Air Bag Supplemental Restraint System (SRS) in this section. CLEAR all DTCs.
Refer to the continuous DTCs recorded during Step K1. Were any continuous DTCs retrieved during Step K1?

Pinpoint Test J: LFC 34/DTC B1934 - Driver Air Bag Circuit Resistance Low

Normal Operation The restraints control module (RCM) monitors the resistance of the driver air bag ignitor by measuring the resistance between pins 3 and 4. If the RCM detects low resistance bet ...

Pinpoint Test L: B1892 - Air Bag Tone Warning Indicator Circuit Shorted to Ground or Open

Normal Operation The restraints control module (RCM) monitors its connection to the generic electronic module (GEM) at C201e pin 10. This connection is used to signal a chime if the air bag indi ...

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