Brake booster works only some time. what do I do?

aspedt2

Registered User
1990 5 spd Thunderbird super coupe , owned for 25 years no problems. Today brake power assist failed, came back on after turning around to come home.. Fluids check okay. Afraid to drive, what needs replacing?
 
1990 5 spd Thunderbird super coupe , owned for 25 years no problems. Today brake power assist failed, came back on after turning around to come home.. Fluids check okay. Afraid to drive, what needs replacing?

If you're talking about the factory ABS, see: http://www.sccoia.org/articles/anti-lock-braking-system/

Could be one or more of these:
- accumulator
- ignition switch down on the side of the steering column (not the key cylinder)
- relay(s)
- pressure switch
 
Power brake booster

If you're talking about the factory ABS, see: http://www.sccoia.org/articles/anti-lock-braking-system/

Could be one or more of these:
- accumulator
- ignition switch down on the side of the steering column (not the key cylinder)
- relay(s)
- pressure switch

Thanks, my mechanic replaced the relay and that solved the problem. The relay switch was very hard to get, as most Ford dealers no lingered carried it
 
1990 T'Bird brake power booster relay

This was replaced and lasted about a week. My mechanic is unable to locate another one. Any suggestions. Incidentally it was very expensive, about $300. I have no power brake assist. Can drive car at all.
 
Sorry, are you talking about the relay(s), or the pressure switch? Was it a new part with a warranty?

Note I've never heard of anyone paying that much for an ABS relay. See: https://shop.advanceautoparts.com/p/bwd-abs-relay-r4135/18970094-P

The last time I bought a pressure switch, it was around $80, 2 or 3 years ago, tho.

AFAIK, both are still available.

It sounds like that mechanic doesn't want to work on your car, tho...
 
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Good luck getting one for $80 today

$113 is a good price today, it seems - thanks for confirming they're still readily available. Looks like they still come w/at least a 12 month warranty. Maybe that $300 was a $200 switch, installed.

Socket was $30 when I did mine.

I had ABS/Brake lights a few weeks ago. No codes, good pedal. Found significant corrosion on both the ABS relay & pressure switch connectors. Cleaned them up and good to go - got lucky. Saving up now to buy a new pump.
 
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KMT is one the best when it comes to expertise and knowledge about these cars. Follow what he says.
Meanwhile, here is good write up and troubleshooting guide for your brake issue.

Assuming that the accumulator is good. It is likely to be one of the following three things: relay, pump or pressure switch.

You have already replaced the relay, I would check the pump next. User small cables to apply power directly to the pump. If it runs, then the pressure switch is the issue.

http://www.sccoia.org/articles/anti-lock-braking-system/
 
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