Power Brakes not working?

Check the things JT mentioned. If everything is ok to that point, ground the pink/blue wire on the front relay momentarily. If the pump starts, the problem is the pressure switch, or the connection to the pressure switch. The pressure switch is the cylindrical switch at the rear of the master cylinder assembly, down at the bottom. It is about 2 inches in diameter. If you disconnect the relay and hook an Ohm meter to the pink/blue wire and ground the other terminal of the Ohm meter you should see about .5-1 Ohm resistance. If you are getting a much higher resistance, say, 50 Ohms, the switch contacts are burnt.

Hawk

Are you sure you replaced the correct relay?

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 21 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 04 Taurus Duratec (wifes car)

The front one of the two next to the vacuum tree that are covered by a black plastic cover

The relay everyone is refering to will have these wires going to it. Tan/Yellow, Gray/Yellow, Pink/Light Blue and Gray/Red. Put 12 volts directly to the Gray/Red wire and see if the pump turns on. You are by-passing everything by doing this. If it doesn't, you have a bad connection or bad pump. If it does turn on, go back to the post by JT and verify that you meet the conditions he posted. If everything checks out there, go to my previous post and check what I posted. What I posted makes the assumption that the relay itself works. To test the relay, turn the key on, ground the Pink/Light Blue wire and check for voltage at the Gray/Red wire. If the items in this post check out and JT's does also, you are back to my previous post. You have a bad pressure switch. I just went though this with an 88 TC. It is not uncommon to have a bad pressure switch. I have sold 2 of them to other people on this list.

Hawk

Did this about 8 months ago, follow the troubleshooting described i also think Jeff K wrote up a tech article (very good). Print this page and the tech article and start trouble shooting, my guess is it is the pressure switch, at least that was always my luck. It is a pain to get to so troubleshoot to know it is the problem first. Good luck.

I went through this crap too and in the end, it was my ignition switch. Just throwing a little fuel on the fire! [Image: wink.gif]

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Ryan Harris

1988 TC 5 speed, all options including sunroof. Currently installing: Walbro 255 LPH HP, Star stage III, Kirban AFPR, 3" DP to 2.5" duals, bypassed cat, Magnaflow mufflers