Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Cadillac >> 1989 >> Allante F7/ME9 >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Body Computer Module >> Diagnostic Tests >> DTC B421: BCM Output Driver No. 2 Failure >> Test Procedure

Test Procedure

  1. It is normal for a Code B421 to set due to an ABS fault (codes B480 or B481). If so, diagnose the ABS codes first. See 1989 ANTI-LOCK -- CADILLAC -- ALLANTE article in BRAKES.
  2. Checks for proper chime control.
  3. Checks for proper RAP control.
Fig 1: DTC B421: BCM Output Driver No. 2 Failure Flow Chart
G00103596Courtesy of GENERAL MOTORS CORP.
Fig 2: DTC B421: BCM Output Driver No. 2 Failure Flow Chart Circuit
G00103597Courtesy of GENERAL MOTORS CORP.
scientia non olet · About Mike's Workshop Manuals