Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnosis & Testing: INTERMITTENTS
To effectively locate fault(s) using charts, problem must currently be present. The diagnostic procedures may help determine the cause of intermittent problems in anti-lock brake system electrical components. Most intermittent problems are caused by faulty electrical connections or wiring.
When an intermittent failure is encountered, check for trouble codes stored in the anti-lock brake controller. If trouble codes are found, inspect related components and circuitry for poor connections. If no trouble code is found, visually check suspected circuits.
- Check for Poor mating of connector halves or terminals not fully seated in connector body (backed out).
- Check for improperly formed or damaged terminals. All connector terminals in problem circuit should be carefully re-formed to increase contact tension.
- Check for poor terminal-to-wire connection. Remove terminal and wire from connector body to inspect.
If visual check does not identify cause of problem, use the ABS-III self-diagnostic system to help locate suspected circuit as follows.
- Display and then clear ABS-III trouble codes in anti-lock brake controller.
- Test drive vehicle, attempting to duplicate conditions that caused problem or complaint. Stop vehicle and record any codes set.
Intermittent operation of anti-lock light may be caused by the following circuits:
- Wheel speed sensor circuits - low or intermittent output
- Main relay - interruption in coil or switched battery power
Program ABS-III snapshot to identify intermittent fault. Use the enhanced diagnostic feature to recreate conditions causing trouble code to set. Determine how often and under what conditions fault occurs. See Tech I (94-00101-A) scanner manufacturer's instruction for more information. Analyze ABS-III snapshot data for unusual conditions.
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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.