Air Bag Restraint Systems: Overview Ford Econoline E150

DESCRIPTION & OPERATION

The Supplemental Restraint System (SRS), also known as air bag system, is designed to provide increased accident protection for driver and front passenger by deploying front air bags and pretensioners in a front-end collision. During a front-end collision, Restraints Control Module (RCM), using inputs from front crash sensor, discriminates between an event that warrants air bag and pretensioner deployment and an event that does not. Air bag system is designed to be used with 3-point seat belts.

SRS includes the following components: Restraint Control Module (RCM), front crash sensor, driver-side air bag module, passenger-side air bag module, clockspring, AIR BAG warning light, left and right front seat belt pretensioners, and associated wiring harnesses. See COMPONENT LOCATIONS .

Scheme 32

RESTRAINT SYSTEM COMPONENT LOCATIONS

SYSTEM OPERATION CHECK

1. When checking air bag system operation (also known as prove out system), and upon completion of each diagnostic test, check for faults in air bag system. To check system, turn ignition switch to ON position. If AIR BAG warning light illuminates for 6 seconds and then goes out, air bag system is functioning properly and no faults exist.
2. If a fault is detected in air bag system during initial system check, AIR BAG warning light will fail to light, remain lit continuously, or flash a code sequence, indicating a fault in system. Flashing may not occur until about 30 seconds after ignition switch has been turned from OFF to ON position. Number of flashes represents a code number used to diagnose air bag system. See «LIGHT FLASH CODES (LFC)»(ref-170321-S07848650612005011000000) under DIAGNOSTICS. If AIR BAG warning light either fails to light or stays on continuously, perform symptom diagnosis. See «DIAGNOSTIC SYMPTOMS»(ref-170321-S28797587752005011000000) table.
3. If a system fault exists and AIR BAG warning light fails to light, a chime will sound in a pattern of 5 tones, or a buzzer will sound for 5 seconds on and 5 seconds off, indicating AIR BAG warning light is out and service is required. Air Bag warning light must be repaired before diagnosis can continue.

Description

During normal operation, the AIR BAG warning light will be continuously illuminated for 6 seconds after the ignition switch is placed in RUN position and after 3 cycles of Light Flash Code (LFC) if a fault exists. Be sure to cycle ignition switch and look for a continuous AIR BAG warning light without LFC.

Restraints Control Module (RCM) will communicate Diagnostic Trouble Codes (DTCs) through scan tool using Data Link Connector (DLC). If scan tool displays NO COMMUNICATION when retrieving continuous codes, go to TEST W: NO COMMUNICATION WITH RCM .

During normal operation, the AIR BAG warning light will be continuously illuminated for 6 seconds after the ignition switch is placed in ON or START position and after 3 cycles of Light Flash Code (LFC), if a fault exists. Be sure to cycle ignition switch and look for a continuous AIR BAG warning light without LFC.

Restraints Control Module (RCM) monitors AIR BAG warning light for open and short to ground conditions. If RCM detects open or short to ground in AIR BAG warning light circuit, it will store DTC B1869 in memory. If RCM detects AIR BAG warning light failure in addition to another air bag system failure, the secondary air bag warning system will be activated.

During normal operation, the AIR BAG warning light will be continuously illuminated for 6 seconds after the ignition switch is placed in ON or START position and after 3 cycles of Light Flash Code (LFC), if a fault exists. Be sure to cycle ignition switch and look for a continuous AIR BAG warning light without LFC.

Restraints Control Module (RCM) monitors AIR BAG warning light for short to battery voltage conditions. If RCM detects short to battery voltage in AIR BAG warning light circuit, it will store DTC B1870 in memory. If RCM detects AIR BAG warning light failure in addition to another air bag system failure, the secondary air bag warning will be activated.

Restraints Control Module (RCM) monitors resistance of circuits to left seat belt pretensioner. When RCM detects resistance that is out of the expected range (high or low), it will store Diagnostic Trouble Code (DTC) B1877 or B1885 in memory and flash Code 33 on AIR BAG warning light.

Restraints Control Module (RCM) monitors circuits to left seat belt pretensioner. When RCM detects a circuit short to battery, it will store Diagnostic Trouble Code (DTC) B1878 in memory and flash Code 33 on AIR BAG warning light.

Restraints Control Module (RCM) monitors circuits to left seat belt pretensioner. When RCM detects a circuit short to ground, it will store Diagnostic Trouble Code (DTC) B1879 in memory and flash Code 33 on AIR BAG warning light.

Restraints Control Module (RCM) monitors resistance of circuits to right seat belt pretensioner. When RCM detects resistance that is out of the expected range (high or low), it will store Diagnostic Trouble Code (DTC) B1881 or B1886 in memory and flash Code 34 on AIR BAG warning light.

Restraints Control Module (RCM) monitors circuits to right seat belt pretensioner. When RCM detects a circuit short to battery, it will store Diagnostic Trouble Code (DTC) B1882 in memory and flash Code 34 on AIR BAG warning light.

Restraints Control Module (RCM) monitors circuits to right seat belt pretensioner. When RCM detects a circuit short to ground, it will store Diagnostic Trouble Code (DTC) B1883 in memory and flash Code 34 on AIR BAG warning light.

Restraints Control Module (RCM) monitors circuits to air bag tone warning indicator. When RCM detects a circuit short to battery, it will store Diagnostic Trouble Code (DTC) B1891 in memory and flash Code 53 on AIR BAG warning light.

Restraints Control Module (RCM) monitors circuits to air bag tone warning indicator. When RCM detects a circuit short to ground or open, it will store Diagnostic Trouble Code (DTC) B1892 in memory and flash Code 53 on AIR BAG warning light.

Restraints Control Module (RCM) checks driver-side air bag module circuits for short to battery or ignition voltage by monitoring voltage at RCM harness connector terminals No. 1 (Gray/Orange wire, circuit No. 614) and No. 2 (Gray/White wire, circuit No. 615). If RCM detects short to battery or ignition voltage in either terminal, it will store Diagnostic Trouble Code (DTC) B1916 in memory and flash Code 15 on AIR BAG warning light.

Restraints Control Module (RCM) monitors resistance between ground connections at its housing and reference ground at RCM connector terminal No. 21 (a resistance difference as low as 10 ohms may set DTC). If RCM detects a difference in resistance, it stores DTC B1921 in memory and flashes Code 21 on AIR BAG warning light.

Restraints Control Module (RCM) checks passenger-side air bag module circuit for shorts to battery or ignition voltage by monitoring voltage at RCM harness connector terminals No. 3 (Light Blue/Orange wire, circuit No. 607) and No. 4 (Pink/Black wire, circuit No. 616). If RCM detects short to battery or ignition voltage in either terminal, it will store Diagnostic Trouble Code (DTC) B1925 in memory and flash Code 16 on AIR BAG warning light.

Restraints Control Module (RCM) monitors resistance of driver-side air bag ignitor by measuring resistance between RCM connector terminals No. 1 (Gray/Orange wire, circuit No. 614) and No. 2 (Gray/White wire, circuit No. 615). If RCM detects high resistance between these terminals, it will store Diagnostic Trouble Code (DTC) B1932 in memory and flash Code 32 on AIR BAG warning light.

Restraints Control Module (RCM) monitors resistance of passenger-side air bag ignitor by measuring resistance between RCM connector terminals No. 6 (Light Blue/Orange wire) and No. 7 (Pink/Black wire). If RCM detects high resistance between these terminals, it will store Diagnostic Trouble Code (DTC) B1933 in memory and flash Code 33 on AIR BAG warning light.

Restraints Control Module (RCM) monitors resistance of driver-side air bag ignitor by measuring resistance between RCM connector terminals No. 1 (Gray/Orange wire, circuit No. 614) and No. 2 (Gray/White wire, circuit No. 615). If RCM detects low resistance between these terminals, it will store Diagnostic Trouble Code (DTC) B1934 in memory and flash Code 19 on AIR BAG warning light.

Restraints Control Module (RCM) monitors resistance of passenger-side air bag ignitor by measuring resistance between RCM connector terminals No. 6 (Light Blue/Orange wire) and No. 7 (Pink/Black wire). If RCM detects low resistance between these terminals, it will store Diagnostic Trouble Code (DTC) B1935 in memory and flash Code 21 on AIR BAG warning light.

Restraints Control Module (RCM) checks driver-side air bag module circuits for short to ground by monitoring voltage at RCM harness connector terminals No. 1 (Gray/Orange wire, circuit No. 614) and No. 2 (Gray/White wire, circuit No. 615). If RCM detects short to battery or ignition voltage in either terminal, it will store Diagnostic Trouble Code (DTC) B1936 in memory and flash Code 19 on AIR BAG warning light.

Restraints Control Module (RCM) checks passenger-side air bag module circuit for shorts to ground by monitoring voltage at RCM harness connector terminals No. 3 (Light Blue/Orange wire, circuit No. 607) and No. 4 (Pink/Black wire, circuit No. 616). If RCM detects short to ground in either terminal, it will store Diagnostic Trouble Code (DTC) B1938 in memory and flash Code 21 on AIR BAG warning light.

Restraints Control Module (RCM) monitor front crash sensor circuits for low resistance, high resistance or open, short to voltage or short to ground.

RCM monitors air bag deployment circuits for a short to another deployment circuit. RCM performs this check only at startup, so an ignition cycle is required for any changes to take effect. B2792 is a stored fault only, and not available during on-demand self test. During each ignition cycle, if RCM detects a cross link fault on any deployment circuit, it will store DTC B2792 in memory and flash Code 72 on AIR BAG warning light.

Scan tool communicates with Restraints Control Module (RCM) through Data Link Connector (DLC) terminal No. 7 (Light Blue/White wire, circuit No. 70).