Diagnosis & Testing: INTERMITTENTS

Failures in anti-lock brake system may be difficult to diagnose accurately. If an ABS failure or fault occurs, ANTI-LOCK indicator will glow. If fault is an intermittent problem which has corrected itself (ANTI-LOCK indicator off), history trouble code will be stored.

Stored history code will display history data of fault at time fault occurred. FLASH CODE DIAGNOSTICS method can be used to identify stored history trouble codes, but Tech 1 must be used to read ABS history data. ABS self-diagnostic system can be used to help find suspect circuit. To do so:

• Record current codes and code history information. Record any descriptive driving circumstances during failure occurrence.
• Use Tech 1, mode F3 (ABS snapshot), while test driving vehicle. See USING TECH 1. Try to duplicate fault condition.
• If no trouble code is stored, use SYMPTOM DIAGNOSTIC CHARTS if necessary.

Most intermittent problems are caused by faulty electrical connectors or wiring. When an intermittent failure is encountered, inspect suspect circuits as follows:

• Check for poor mating of connector halves or terminals not fully seated in connector body (backed out).
• Check for improperly formed or damaged terminals. Carefully reform all connector terminals of problem circuit to increase contact tension.
• Check for poor terminal-to-wire connection. This requires removing terminal from connector body to inspect.