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My light stays on all the time. I have swapped 4 different relays and a known good brain box and no change. Seems like the ABS pump is next on the list to swap.
My question: Anything special to swapping in a new pump or is it just unbolt/install and bleed the brakes like usual? Before i do this should i swap out all the relays on top of the pump first?
Thanks
[quote=“RacerDan” post=58210]My light stays on all the time. I have swapped 4 different relays and a known good brain box and no change. Seems like the ABS pump is next on the list to swap.
My question: Anything special to swapping in a new pump or is it just unbolt/install and bleed the brakes like usual? Before i do this should i swap out all the relays on top of the pump first?
Thanks[/quote]
Just to double-check, your ABS light comes on before you actually move the car, correct?
Nothing tricky about replacing the pump. Hit the pipe connector ends with a torch to get them to expand before wrenching with a brake line wrench. The cable connects to the pump under a plastic cover. Some of those covers have a visible screw fastening them on, some covers have a plastic cap covering the screw that you have to pop off, and some have a rivet fastening the cap that has to be drilled out.
Fish did a big write up here about ABS electricals that will be handy if replacing the pump doesn’t do it.
If you need a pump, I’ve got a couple in my attic. They’re kinda heavy so $50 shipped.
Dan - I would try swapping out the ABS pump relays (under the black panel on the pump) first before swapping the pump out. I also have a known working ABS pump as a spare.
Did you try replacing all of the wheel sensors? My car should have some down-time after the race at VIR in two weeks, maybe try using my wheel sensors?
Thanks guys. Light comes on at startup and doesn’t go off - moving or not.
Rob i tried your relays - one worked (no change to the light) and one didn’t fit. It looked like your pump was a bit different than mine.
Ranger - you going to be at VIR in July? I would like to try a known good pump than a junkyard pump. If you are going i will give you the part#'s from my pump to check against yours (mine is an 87) to make sure they are the same.
Thanks again.
Since symptoms don’t point to sensor and you’ve swapped all else, it does sound like swapping the pump is the next logical thing. But before you do that, find Fish’s (Richard Bratton) ABS write up and use it to check your ABS wiring harness.
Be sure to torch the brake line connectors before you chew the shit out of them with a wrench.
I won’t be at VIR but Al Taylor lives near there and I’m sure he has a pump he can bring to the event. Send him an email via “Members”.
It sounds like you have a bad alternator, control module or pump unit. To rule out relays and electrical wiring issues, you need to take some voltage readings. Readings at the main ABS connector should read as below:
-Pin 1: should read ~14v with car running. Will not have voltage if main relay is bad.
-Pin 10, 20, and 34: Ground.
-Pin 15: 14v with car running. This is the charge indicator from the alternator. If this doesn’t check out, you have a charging issue which could be bad wiring or a bad alternator.
-Pin 25: 14v when you activate brake switch; no voltage with brake switch open.
-Pin 29: .65 to .75 volts; this is the green red wire on the negative side of the warning light.
If the issue is not charging, relay, or wiring related then your problem is with the pump unit or control module. You’ll need to swap with known good units to isolate the problem.
While you are checking electrical connections, you might as will check your wheel sensors. Each circuit should measure about 1000 ohms (rears 1100ish); FL-Pin 4 and 6, FR-Pin 11 and 21, RR-Pin 24 and 26, LR-Pin 8 and 9. A bad wheel sensor is obvious as the light initially goes out, but comes on after moving 50 ft or so.
Don’t forget to check the wiring from the sensors. I had a front ABS sensor wire ever so slightly rub on the tire and wear through the harness just enough to short it out. I never noticed until I inspected it closely.