Code 21 & 22 Both Current, Steering Column Resistance Undetermined: Description
WARNING: This page is about a different car, the 1991 Geo Storm, 1991 Geo Metro, 1990 Geo Storm, and 1990 Geo Metro. However, it is still accessible from the selected car via links, so may be relevant.
DERM injects a current of 75 milliamperes through steering column from FORCE HI output (terminal No. A4) to FORCE LOW input (terminal No. A10). By monitoring voltage at SENSE HI input (terminal No. A7) and SENSE LOW input (terminal No. A6), DERM calculates combined resistance of inflator module, SIR coil, harness wiring and connector terminal contact in steering column. Codes 22 and 21 will set if FORCE HI output (terminal No. A4) is open.