Brake problem

Ok I changed the relays under the hood. Now the pump just runs and runs and runs!! Just a constant buzzing noise!! What's this mean? Before I changed the relay, the brake and ABS light would come on and once I pumped the brakes, the light would go out and the pump woulkd turn off. Now with the new relays, the light does not come on in the dash, but I have vthis constant buzzing niose from the master cylinder. Help!!

If the pump in the MC runs with the key off, the only possible causes are a bad pump relay (contacts welded themselves shut), or a wiring short that shorts the 2 wires that go to the relay contacts together (not likely, but possible). If the pump runs constantly with the key on, pull the connector off the pressure switch on the MC (5 wires, hard to get to, next to the pump motor). If the motor shuts off when the connector is pulled off the press sw, the press sw is likely bad.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 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 // 02 Taurus Vulcan(wifes car)

Jeff, I pulled the wire off the 5 wire thing that looks like a ice cream cone, and it still kept humming. Does that mean its bad and must be replaced?

If you pulled the 5 wire connector off the pressure switch on the MC, and the pump still runs, sounds like the relay is stuck shut, a common problem (so common, I carry a spare relay in my trunk).

If the pump runs with the key off, then there is a 99.9% chance the relay is bad. It is one of the3 relays under the vac tree. It is the relay with the GY/Y, T/Y, GY/R, PK/LB, and GY wires.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 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 // 02 Taurus Vulcan(wifes car)

If I pulled the connector off, how is it getting power to continue running? This is only with the key in the on position. Help!!

If the pump always runs only with the key on, but shuts off when you turn the key off, the problem is not the relay. The strange part is that it runs when you pull the 5 pin connector off the pressure switch. That should shut the pump off. The relay coil gets 12V with the key in the ON (run) position via the GY/Y wire. The other side of the relay coil, PK/LB wire, goes to the pressure switch. The GY wire from the press switch goes to ground. WHen the press in the accumulator drops below a set value (about 2100 psi), the press sw closes, which grounds the relay coil, and the pump runs. Since the pump runs with the key in run, but not with key off, and press sw disconnected, the only possible causes are a short to ground in the PK/LB wire between the relay and the press sw, or a really weird relay problem. I am betting on a short to ground in the PK/LB wire somewhere. CHeck the relay socket to be sure there isnt a short between the PK/LB and GY wires (GY is grounded). Also, for the hell of it, switch the pump relay and the ABS power relays around (switch the 2 relays under the vac tree), and see if the pump now runs normally. If it does, the relay is bad, but I doubt that is the case.

One more thing.... I am pretty sure you pulled the 5 pin connector off the right thing,, but just to verify, you pulled it off the cylinder that is about 1" dia, few inches long that is parallel to, and just in front of the pump motor, right?

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 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 // 02 Taurus Vulcan(wifes car)