Chart A1 - History Code Diagnosis: Description
When ignition is first turned on, system voltage is applied through fuse No. 6 to SIR INDICATOR HIGH input and INFLATABLE RESTRAINT indicator light, which is connected to SIR INDICATOR LOW input. Fuse No. 7 also applies system voltage to IGNITION 1 inputs. DERM responds by flashing INFLATABLE RESTRAINT indicator 7-9 times.
When engine is cranked, system voltage is applied to DERM at CRANK input. DERM grounds light circuit until system voltage is removed from CRANK input. This results in a steady INFLATABLE RESTRAINT indicator during cranking. After cranking, DERM again flashes INFLATABLE RESTRAINT indicator 7-9 times.
NOTE:
Test numbers refer to numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS.
WARNING:
To avoid air bag deployment while trouble shooting SIR system, only use test equipment specified in diagnostic charts. Under no circumstances should battery powered test equipment or test light be used. Carefully follow all instructions.
- DERM determines arming sensor is closed when system voltage or more is present at SENSE HIGH input and determines a discriminating sensor is closed when it notes low voltage at SENSE LOW input. Some faults can look like an accident to DERM and set a Code 51. History Code 51 is not proof vehicle was in an accident.
- When a History Code 51 is set, History Code 34 does not set. Any conditions which cause a Current Code 34 to set do not set a History Code 34 when a History Code 51 is set. When INFLATABLE RESTRAINT indicator alerts owner intermittently of a current code and no corresponding history codes are set, most likely cause is an intermittent open in circuit No. 1139.
- Checks for intermittent electrical conditions in steering column.
- Checks for intermittent shorts in 36VLR wiring (circuit No. 236).
- Checks for open or mis-installed fuse No. 6 for poorly installed INFLATABLE RESTRAINT warning light bulb or for uncleared Code 61 after a completed wiring repair on circuit No. 39. Also checks for intermittent faults in circuits No. 688 and 358.
- Checks for intermittent opens in ground path of deployment loop between base of steering column and discriminating sensors.