P38 abs pump quesitons

[Gordo]

Hey guys, my wifes 00 4.6 is having an issue. The brake light came on while I was out of town. I had her go out and pump the brakes with the key off and then turn the key back on and the pump came on and the light went out. I had her repeat this process multiple times and all was well, so I told her to drive it but to be careful. Anyway, it came back on today and when I got home the abs pump is not running. I pulled the plug to the pump (which looks like a o2 sensor plug correct?) and there is no power to the pump. I pulled the abs relay and it clicks when I put it back in but no power to the pump. The relay has power at two terminals. I plan on running power to the pump to see if it comes on directly but Im a bit confused on what to fix, even it the pump works hardwired. The pump was quiet and after depressing the pedal came on for about 20 seconds and then switched off no problem and holds pressure well, or at least it did when it worked. Thanks for any help. Gordo.

 

[Gordo]

Ok so I out there tinkering on it and I found a loose wire at the bottom of the fuse box which the dealer replaced prior to me buying it. So now the ABS pump is working, and the brake light goes out, sometimes! It comes back on after a few pumps, although the pump is cycling properly. It seems to cycle after just a few pumps so Im wondering if that is a sign the accumulator is bad, and if so would that cause the brake light to stay on like that. The brakes feel fine now. Thanks. Gordo

 

[RVRSRVC]

I 've had pump failures due to excessive use as a result of a weak accumulator, and I guess it could work inthe opposite direction- an accumulator fails from trying to make up for a "faulty" pump.
the accum isn't horribly expensive-but less expensive than a pump that dies from trying to overcome a weak accumulator!

 

[Gordo]

Thanks. I forgot to mention that the ABS relay fell when I was pulling it out and I popped the lid off and cracked it. I popped it back in but Im wondering if that could cause the light to go on? Seems odd that the light is coming on but the brakes are working fine. Im confused and I dont just want to throw parts at it! Keep the advice coming. Gordo.

 

[Gordo]

Well I put the new relay in and no luck. I really think it is just the pressure switch but I dont know where to get it without buying a pump. I may just buy a used pump and see if that fixes it. Gordo

 

[az_max]

My RRC accumulator caused the failure of my pump. It was fairly obvious once I realized it; the brake resevour was empty. It was all in the accumulator ball.

 

[Gordo]

Thanks for the heads up. The fluid is full on mine, but the accumulator comes on after a couple pumps so its probably just about done. Thinking Will Tillery at this point! Gordo

 

[thedude]

I 've had pump failures due to excessive use as a result of a weak accumulator, and I guess it could work inthe opposite direction- an accumulator fails from trying to make up for a "faulty" pump.
the accum isn't horribly expensive-but less expensive than a pump that dies from trying to overcome a weak accumulator!

i can validate that! happened to me.