Automatic Tests

1996 Buick Roadmaster BaseSECTION Automatic Tests

Turn ignition on. Using Tech 1, select F4: MISC TESTS and then F1: AUTO TEST. Press ENTER when ready. Valves can be heard and felt cycling from hydraulic control unit. Have assistant verify pump motor is turned on. See DIAGNOSTIC TROUBLE CODE (DTC)  table if DTCs are set. See DIAGNOSTIC TROUBLE CODE CHARTS . After all diagnosis and repairs are completed, clear DTCs and verify operation. AUTO test is performed automatically by EBCM once during each ignition cycle when vehicle reaches approximately 4 MPH.

DIAGNOSTIC TROUBLE CODE (DTC)

DTC (1) Definition
12 Diagnostic System Operational
21  Right Front Wheel Speed Sensor Circuit
23  Right Front Wheel Speed Sensor Continuity
25  Left Front Wheel Speed Sensor Circuit
27  Left Front Wheel Speed Sensor Continuity
28  Wheel Speed Sensor Frequency Error
35  Rear Axle (Wheel) Speed Sensor Circuit
37  Rear Axle (Wheel) Speed Sensor Continuity
41  Right Front Inlet Solenoid Valve Fault
42  Right Front Outlet Solenoid Valve Fault
45  Left Front Inlet Solenoid Valve Fault
46  Left Front Outlet Solenoid Valve Fault
55  Rear Inlet Solenoid Valve Fault
56  Rear Outlet Solenoid Valve Fault
61  Pump Motor Or Relay Fault
63  Solenoid Valve Relay Fault
71  EBCM Fault
85  Low Voltage
(1) Always perform ABS system functional check before using DIAGNOSTIC TROUBLE CODE CHARTS. See Figure.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.