C1266-2: Check Anti-Lock Brake Module Ground For Open Circuit

- Carefully disconnect breakout box adapter from anti-lock brake module. Breakout box and vehicle harness remain connected.

- Using an ohmmeter, measure resistance between breakout box pin 1 and a known good ground.

- Is resistance less than 5 ohms?

YES -- Go to C1266-3. C1266-3: Check ABS Valve Power Circuit For Short to Ground

NO -- Service circuit 570 (BK/W) for open. Restore vehicle. Retest system.