Action Taken

DERM turns on INFLATABLE RESTRAINT indicator light.

NOTE: Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

Checks whether fault is in steering column or diagnostic circuitry.
Checks integrity of 430-ohm resistor and associated circuitry in resistor module.
Checks integrity of 49.9-ohm resistor, 100-ohm resistor and associated circuitry in resistor module.
Checks integrity of two 2490-ohm resistors and associated circuitry in resistor module.
Checks whether steering column fault is due to SIR coil or inflator module.
Checks integrity of circuits No. 347C, 348B, and inflatable restraint wiring harness-to-SIR coil connection.
Checks for a short from FORCE HIGH circuit to SENSE HIGH circuit.
Checks for a short from SENSE HIGH circuit to voltage.
Checks whether fault is in circuit No. 347C or 348B.

Fig 1: CODE 21, CHART 1, Steering Column Resistance too High

Courtesy of GENERAL MOTORS CORP.

Fig 2: CODE 21, CHART 2, Steering Column Resistance too High

Courtesy of GENERAL MOTORS CORP.