Ford Mustang (1999-2004) Service Manual: 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 indicator is inoperative and another SRS fault exists. If the RCM detects a short to ground or open on the connection to the GEM, it will store a diagnostic trouble code (DTC) B1892 in memory.

Possible Causes

An air bag tone warning indicator circuit short to ground or open can be caused by:

  • a short to ground or open on circuit 1083 (LB/BK).
  • a damaged or inoperative GEM.

PINPOINT TEST L: DTC B1892 - AIR BAG TONE WARNING INDICATOR CIRCUIT SHORTED TO GROUND OR OPEN

Test Step Result / Action to Take
L1 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 L2 .

No

This is an intermittent fault.

The fault condition is not present at this time. GO to L5 .

  • 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 B1892 retrieved during the on-demand self test?
L2 CHECK THE AIR BAG TONE WARNING INDICATOR CIRCUIT Yes

REPAIR the circuit. GO to L6 .

No

GO to L3 .

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.
  • Disconnect: RCM C2041.
  • Disconnect: GEM C201e.
  • Measure the resistance between RCM C2041 pin 26, circuit 1083 (LB/BK), harness side and RCM C2041 pin 21, circuit 397 (BK/WH), harness side.

  • Is the resistance less than 10,000 ohms?
L3 CHECK THE AIR BAG TONE WARNING INDICATOR MODULE CIRCUIT Yes

REPAIR the circuit. GO to L6 .

No

GO to L4 .

  • Measure the resistance between RCM C2041 pin 26, circuit 1083 (LB/BK), harness side and GEM C201e pin 10, circuit 1083 (LB/BK), harness side

  • Is the resistance greater than 10 ohms?
L4 CHECK THE AIR BAG TONE WARNING INDICATOR Yes

INSTALL a new GEM. GO to L6 .

No

INSTALL a new RCM. GO to L6 .

  • Disconnect: GEM C201e.
  • Key in ON position.
  • Measure the voltage between RCM C2041 pin 26, circuit 1083 (LB/BK), harness side and ground.

  • Is the voltage less than 1.0 volt?
L5 CHECK FOR AN INTERMITTENT FAULT Yes

CHECK for causes of intermittent short to ground or open on circuit 1083 (LB/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 L6 .

No

GO to L6 .

  • Refer to the continuous DTCs recorded during Step L1.
  • Was the continuous DTC retrieved during Step L1 an intermittent fault?
L6 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 L1.
  • Were any continuous DTCs retrieved during Step L1?
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