Brake problems, a suggestion

[Barney Eaton]

After reading the discription of operation in the service manual, there is a very simple step you can take that might solve your problem.<BR>There are two relays located on the firewall next to the brake assembly, that are in the ABS/brake circuit. The MAIN relay is located closest to the brake asm, and the PUMP relay is next to the MAIN relay, toward the passanger side of the car. <BR>These relays must work. If the Main relay is bad, you have no ABS. If the Pump relay is bad, you have no pump operation and no boost which gives you the very hard pedal.<BR>First unplug and replug the relays. This will clean the connector contacts. If you still have one problem or the other, switch the relays, this will move the problem (if the relay is bad)<BR>Example, if the Main relay is bad, the ABS light will be on, but the pedal will feel fine and the car will stop. By moving (switching) the relays, the problem will move to the pump... the pedal will get hard and it will feel like you have no brakes.... but the ABS light will probably still be on because there is little or no boost pressure.<BR>The relays are available from parts houses and are usually less than $10.<BR>Someone with more time might be able to probe a relay and draw a schematic to tell us what pins to probe to verify a defective relay.<P>I recommend unplugging and replugging the relays even on cars that have no brake problems. Remember, contact contamination can be intermittant and you can have a problem without warning.<P>Comments welcome... If you want to talk one on one, give me a call, 8am-9pm Texas time.<BR>512-869-5114<P>------------------<BR>Barney Eaton Reatta technical advisor for BCA and keeper of the Reatta database.

[Guest wally888]

Someone on the forum provided me w/ these instructions for checking the relays there is a wiring diagram printed on the relay)<BR> Apply 12 volts across terminals 85 and 86.<BR>Relay should click each time power is applied and each time removed. BUT I think buying one new one and switching to both or switching are best test.Mine was interrmittant and w/ my luck it would have been o k when tested altho was bad!<BR> I purchased at Advanced Auto Parts for $8-#MR116<BR>

[Guest]

Good test procedure. I'm with Wally, if the cost is that low, just replace the things every so often, and keep a spare in the trunk for road trips.<P>If the relay isn't the problem, you haven't lost much money and you've elminated a potential source of problems.<P>Nice that the relays are interchangable. Hat's off the engineers on that one!<BR>

[wheresjim]

Wally, if you want to send me the wiring diagram I can post it on one of my sites so that everyone can see it.<P>Send it to wheresjim@hotmail.com

[Guest Greg Ross]

Also bear in mind that this is probably the hottest air temperature zone in the engine compartment with the transverse mounted drive train if the vehicle sees a lot of stop and go traffic. On my '88 after I purchased it, I thought those particular relays appeared rather baked so I replaced them strictly as a preventative maintenance measure. At the time I was not even aware of their function and presto my ABS light quit activating.