1985-1998 [Subscribe to Daily Digest] |
This type of experience is why many of the posters on this board learn the basics of DIY repairs.
The '94 SRS is is much simpler than the earlier systems in that it only has a single momentum crash sensor located on the floor inside the car behind the dash console. As it is inside and protected from the elements and road spray, it almost never fails. What does fail on a routine basis in the 9000 series is the "clock spring" connector inside the steering wheel behind the air bag. If you disconnect the battery, it is relatively simple to use a volt/ohm meter to measure continuity between the connectors for the air bag and wiring harness.
As far as the ABS goes, most of the problems with this car's ABS are associated with the wheel sensors. Think about it... The ABS pump only runs when the ABS is activated, so unless you have a problem with corrosion (usually connector associated) the pump is unlikely to fail (at least mechanically) during the normal life cycle of the car. The sensor wires, on the other hand, constantly flex as the wheels bounce and turn. Furthermore, since the Hall effect sensors have internal magnets, they are suseptable to picking up magnetic debris that attenuates the signal from the trigger wheels located on the axle bearings. (The trigger wheels, themselves, can also sometimes become packed with metallic crud that disrupts the sensor signal to the ABS control box.)
The place to start with the '94 Mark IV ABS diagnosis again involves a volt/ohm meter. On the '94, you need to access the control box that is located in the compartment near the windshield that is covered by a plastic cover secured by 8 screws and the front compartment rubber seal that runs along the top edge of the engine compartment false bulkhead. The ABS control box is located in the left front corner (driver's side in the US) along side the engine control box. The ABS box is the gold anodized one closest to the engine that has a long blue and black connector facing upwards. (The engine ECU is silver and has the connector attached to the bottom, and thus not visible without removing the box.) The ABS control box connector disconnects by lifting up on the metal strap that secures it to the control box housing. (No need to remove the box itself, unless perhaps, to read the connector numbering. If necessary, the ABS box can be removed by removing the 8 mm head bolt on the side that also holds a grey connector to the side of the box slot and sliding the ABS box straight up.) Inside the connector, connections for the individual ABS whee sensors can be found. When I get home, I will look up the connection sensor locations and post them. (They also may be in the BBS archives somewhere.) Basically, to check the sensors with the VOM, you measure the resistance across pairs of the individual connections - they should all be ca. 1100 ohms +/- 100 ohms. Anything much higher or lower indicates a failed wheel sensor that can, with some effort also be replaced by a competent (and determined DIYer).
Given what you are spending and the results you have received thus far, the time invested in these measurements would be well worth it. If these diagnostics don't uncover the faults, you ar eprobably better off going to a qualified dealer than continuing to pay for your indie's learning experiences.
SteveB
posted by 165.170.12...
, Thu, 4 Jun 2009 10:11:23
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