On-Board Diagnostics, Initiating

Test requirements
^ Tires on all wheels must be of the same (approved) size and inflated to the specified pressure.
^ Mechanical/hydraulic parts of the brake system with brake light switch and brake lights OK.
^ Hydraulic connections and lines are sealed properly (visual check at hydraulic unit, brake calipers, wheel cylinders, tandem master brake cylinder).
^ Harness connector on ABS control module -J104- properly connected (retainer catch engaged).
^ Check connector terminals of ABS components for damage and proper seating.
^ All fuses are OK according to wiring diagram (remove fuses from fuse holder for test).
^ Supply voltage OK (at least 10 volts).
^ The OBD sequence can only be started with the vehicle stationary and the ignition switched on (or with the engine running).
^ Be sure that vehicle electronics are not exposed to electromagnetic forces while the ABS system is being tested. Keep vehicle at a distance from devices with strong current draw, e.g. electric welding tools.

Safety precautions

WARNING:
^ Test equipment must always be secured on rear seat.
^ Drivers must NEVER operate these tools while driving.