3.4 ABS Troubleshooting
Before beginning any troubleshooting of ABS electronics, check the battery, check the brake fluid level in the reservoir, check all electrical harness connections and grounds, and visually inspect connector contacts for damage or corrosion. Table b lists a series of electrical checks which are to be performed at the control unit harness connector with the connector disconnected. Following this series of tests in order will provide a thorough functional test of all system components except the control unit.
WARNING-
Make all connections to the control unit connector with the ignition off.
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NOTE-
Beginning 1/89 with VIN KK 001 000, the ABS control unit (Volkswagen Part No. 535 907 379 or Part No. 357 907 379) has self-diagnosis and fault memory. Volkswagen dealer technicians use special electronic test equipment to access the fault memory and display coded fault information. Volkswagen recommends that a check of the fault memory should be the first step in any ABS troubleshooting.
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Table b. ABS Troubleshooting
| Fig. 3-1. | Electrical harness connection (arrow) for ABS three-way valve. |
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| Fig. 3-2. | 7-pin electrical harness connection (arrow 1) for ABS valve block. Electrical harness connection (arrow 2) for ABS pressure switch. Electrical harness connection (arrow 3) for ABS hydraulic unit. |
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