ABS & brake light, 1 year after a reman accumulator

Hate to post a brake question, but I'm not finding this exact situation.

This just started today. Sitting at a light, the ABS & brake lights came on. Brakes felt ok, not going to the floor, not getting hard pedal. I turned the car off, then started back. The accumulator charged up, no lights, seemed fine. Keep driving. At another light, they came on again. Still no flashing, just on. Made my stop, got back in the car started, lights went off as usual. Didn't come back on, but it was a very short drive home.

I tried pulling codes fom from the ABS plug in the trunk, but the light never flashed, so I guess no codes (3 times I did this).

I replaced the accumulator last spring. Fluid level looks fine. Am I missing something here?

It's not acting like the accumulator problem again, not sure what's going on. Is this a symptom of the main unit going out?

JAFO said:

It's not acting like the accumulator problem again, not sure what's going on. Is this a symptom of the main unit going out?

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Maybe.. could also be the pump motor relay... its cheap, replace it!

I read about the relay but I didn't think that's what it sounded like since it wasn't constant and there's no code.

This morning, after starting it took a lot longer for the lights to go off. Maybe because I was messing with it last night and had more to do, I don't know. I usually wait for the lights to go off before moving, but after about a minute I eased out. Brakes worked on first light pump then went hard as in no power assistance. It did stop. Sat a minute, lights went off, no problems. On the way to work I had an open road so I tried some hard braking. No lights, did this 3 times just to be sure my rotors were properly warped. I didn't catch any lights to test sitting with the brakes on, so when I got here I sat in the parking lot for a minute holding the brakes on. Nothing. Pumped 30 times, no lights.

Does that sound like the relay? Would that slowly go out or go all at once? Wouldn't it throw a code if it was going out? Could be that I didn't pull the code right. Used the Actron scanner, plugged into the red ABS hookup in the trunk. Moved it to test and then turned the car to "on" (not started). No flashing ABS light, just a steady light. Tried hitting the brakes a couple of times, no flashing just a steady light.

Thanks for the help. I'm fine with replacing the relay, just worried it might be a bigger issue.

If you read the Ford Shop Manual it explains ABS operation that at 20mph the ABS pump motor pressurizes. The delay you see could be just that. The first time you hit 20mph and the light comes on you have verified a bad pump.

Rich

I guess that's a positive thing then, since the light came on at a stop with brakes on sitting at a light. One possibility down.

JAFO said:

IDoes that sound like the relay? Would that slowly go out or go all at once? Wouldn't it throw a code if it was going out?...

Thanks for the help. I'm fine with replacing the relay, just worried it might be a bigger issue.

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Yes. Relays do 3 things when they have problems.. either they don't engage, or they stick, or the contacts go bad. They can act normal 1 minute and have problems the next.

The normal power assist braking with the pump is actually separate from the ABS controls (even though its all wrapped up in one big master cylinder thing). The ABS computer doesn't know anything about the pump, the pump relay, or the normal hydraulics, so it can't set a code.

Rich Thomson said:

If you read the Ford Shop Manual it explains ABS operation that at 20mph the ABS pump motor pressurizes. The delay you see could be just that. The first time you hit 20mph and the light comes on you have verified a bad pump.

Rich

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What year and model is that manual for? because I can't see any ABS control for the pump motor itself from the wiring diagram that I have for the Teves II.. I can see the pump motor being driven off the pump motor relay which is in turn directly driven from the pressure switch with with no ABS computer inbetween. Its purely pressure based.. as pressure drops.. the motor runs.. when it reaches its setpoint, it stops. You could completely remove the ABS computer from the car and you would never even know that it was gone unless you locked up the brakes and scratched your head as to why the anti-lock didn't engage. Everything else would work normal.

JAFO said:

Hate to post a brake question, but I'm not finding this exact situation.

This just started today. Sitting at a light, the ABS & brake lights came on. Brakes felt ok, not going to the floor, not getting hard pedal. I turned the car off, then started back. The accumulator charged up, no lights, seemed fine. Keep driving. At another light, they came on again. Still no flashing, just on. Made my stop, got back in the car started, lights went off as usual. Didn't come back on, but it was a very short drive home.

I tried pulling codes fom from the ABS plug in the trunk, but the light never flashed, so I guess no codes (3 times I did this).

I replaced the accumulator last spring. Fluid level looks fine. Am I missing something here?

Click to expand...

Try replacing the ABS Pump Relay Switch (called the Brown Relay). You can check other threads, but it is located on the firewall, passenger side. It's not expensive ($25 or so). I had a similar problem, replaced that switch and it solved the problem)

Got one at O'Reilly's, at least I think it's the right one. Looks right, but not brown (black) like the original. I guess it isn't just one company that makes them for everyone. It's $17.99, p/n R647. If it's the wrong one somehow I'll be back.