Test 3C: No Response From Left SIACM
NOTE:
Prior to performing any air bag system test, go to PRETEST INSPECTION & DIAGNOSTIC PROCEDURE
under DIAGNOSTICS. Perform air bag verification test after all repairs unless otherwise directed. See TEST VER-1: AIR BAG VERIFICATION TEST
under DIAGNOSTIC TESTS.
- Disconnect negative battery cable and wait at least 2 minutes. Connect DRB to DLC connector. Turn ignition switch to ON position. On DRB select PASSIVE RESTRAINT, AIRBAG and read active DTCs. If DRB displays LOSS OF IGNITION RUN-START, go to DIAGNOSTIC TESTS and perform appropriate procedure. If DRB does not display LOSS OF IGNITION RUN-START, go to next step.
- Disable air bag system. See DISABLING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Access and disconnect left SIACM connector. See SIDE IMPACT AIR BAG CONTROL MODULE (SIACM) under REMOVAL & INSTALLATION. Measure resistance between ground and left SIACM connector terminals No. 5 and No. 6 (Black wires). See Fig 1 . If resistance is less than 5 ohms for both circuits, go to next step. If resistance is more than 5 ohms for either circuit, repair open circuit in appropriate black wire between left SIACM connector and ground.
- Turn ignition switch to ON position. Connect negative battery cable. Measure voltage between ground and left SIACM connector terminal No. 1 (Light Green-Yellow wire). If voltage is less than 6 volts, repair open circuit in Light Green-Yellow wire. If voltage is more than 6 volts, go to next step.
- Using Scope Input Cable (CH7058), connect scope input cable to DRB channel one connector. Using Cable-to-Probe Adapter (CH7062) and Red and Black test probes, connect cable-to-probe adapter and Red and Black test probes to scope input cable. On DRB select PEP MODULE TOOLS, LAB SCOPE, LIVE DATA and 12 VOLT SQUARE WAVE. Press F2 for scope and ENTER to select channel. Press F2 and use down arrow to set voltage range to 20 volts. Press F2 when voltage range is set. Connect Black test probe to body ground. Connect Red test probe to left SIACM connector terminal No. 2 (Violet-Yellow wire). If voltage reading on DRB display pulses from 0-7.5 volts, replace left SIACM. If voltage reading on DRB display does not pulse from 0-7.5 volts, go to next step.
- Turn ignition switch to OFF position. Disconnect negative battery cable and wait at least 2 minutes. Disconnect Body Control Module (BCM) 26-pin connector. Measure resistance between left SIACM connector terminal No. 2 and BCM 26-pin connector terminal No. 21 (Violet-Yellow wire). See Figure & Fig 1 . If resistance is less than 5 ohms, replace BCM. If resistance is more than 5 ohms, repair open circuit in Violet-Yellow wire between ORC connector and BCM 26-pin connector.
NOTE:
Ensure there is PCI bus communications with other vehicle control modules. Diagnose and resolve any PCI bus malfunctions before proceeding to next step.