The ABS light came on and there is a hissing noise coming from the ABS unit. The brakes work fine. Any ideas?

 

abs is to keep you from locking the brakes up so you dont slide when tryen to stop quickly. so you should still have brakes.

if its hissing, sounds like a leak maybe.
any fluid on the ground??

 

Have you tried getting the ABS to engage under braking? Is the light flashing? If so, how many times? There's a thread somewhere around here with number of flashes/codes telling you exactly what's wrong.

 

No leaks on the ground or engine bay.

Haven't tried to brake hard. Normal braking is OK.

ABS light doesn't flash.

 

Also, I just pulled off the battery cable, as I think if it continues to run, the battery will be dead by the morning.

 

its still hissing after you shut off the car?????

 

Yes. Definitely still under pressure.

 

does it still have power?
or does it sound like leaking internally?

 

Not sure about power, until I drive it tomorrow and brake hard. Leak sounds internal.

 

What your hearing is the ABS pump running, it's stuck on for some reason. The FSM shows how most of the components in the ABS systems can be tested with a volt/ohm meter. The first thing I would test is the pump relay.

 

The pump relay is known for sticking and keeping the pump running .

 

The ABS system isn't rotary specific.........

In other words, you can take it to the dealer & have him hook up his magic machine to diagnose the problem.........

You can guess all you want. The FSM has a wonderful troubleshooting section, but you need to get ahold of alot of the special tools listed.

But beware...........You now have extremely front brake bias with no ABS. You will rear-end someone if your not careful. I would get it fixed ASAP.

Short story


I got the ABS light & experianced massive front brake lock up after the finish line at a autocross event.

When I opened the hood I could hear the ABS Motor running. Even after I shut engine off, the ABS Motor continued to run.

I pulled the ABS fuses (40 & 15 amp) from the fuse/relay box near the left strut tower. This shut the ABS Motor off, but I still had the light & some serious front brake bias.

When I put the fuses back in the ABS Motor started running again. After a while, 1/2- 1 hr, I put the fuses back in again & all was back to normal. It stayed that way for a couple of months.

Then during a lapping day I got massive front brake lock up (the right front taking the brunt) & ended up flat spotted my R compound tire to the cord. I got the ABS light again. Back in the pits, with the hood up, I could hear the ABS Motor running once again.

The ABS Hydro Electrical unit (r/h corner of the engine compartment) has two relays under the plastic cover. One is for the Pump Motor & the other is for the Valve.

I tested both relays with voltage. They operated normally. I then heated the Pump Motor relay up to 250' F & tried again. The damn thing stuck closed. After it cooled down it snapped open again.

That's why the system would return to normal if I waited to put the fuses back in.

During normal street driving you don't get into the ABS much, if at all. On the track it must be cycling on & off a bunch.

Summary? I replaced both relays in the ABS Hydro Elect unit. They cost around $60 for the pair.

 

Thanks. I was thinking of pulling the fuses late last night. The track days for this car were over a few years ago. Bought a FB for the track.

 

My car did the exact same thing ocasionally. It turns out that whoever painted my car removed the ABS computer (mounted to the driver side rear quarter) and left it hanging in the rear compartment. The abs computer was not grounded to the chassis. Once i found some new bolts and reinstalled the abs computer to the chassis ground the pump recirculating (hissing) stoped happening.

EVERYONE that has had this happen to them, check the ground to your A.B.S. computer!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

I pulled the 40 amp fuse and the hissing stopped. The 15 amp fuse had no effect (still hissed). I'll wait a few days and re-install the fuse and see what happens.

 

Amazing this just happened to me today. Same deal, had to pull the battery cable to get the pump to shut off. Usually when you first start the car and begin rolling, the pump will cycle on and off, but this time it stuck on. After pulling the battery cable and reattaching it, I restarted the car and drove a bit and the pump cycled normally. Sounds like my relay is going bad so I guess I'll just replace both of them. Anyone know the part #s?

 

jack up the car and inspect the VSS on the car, or the abs sensors. They might be dirty or cracked, if so, change em it should fix the problem. Also, check for materials that built up in the speed ring gear and make sure nothing is stuck to it. Cracks, dirt particle build ups can cause this to happen. Also check the relay like someone else earlier explained. If all goes well, check the abs unit itself. And no, u dont need too much tools to get this diagnosed. All you need is a DMM (digital multimeter). By comparing the specs with the manual for resistances and voltages, you should be able to find the culprit easily.

 

I'm going to start with the relays first as the nature of the problem definitely suggests a sticking relay. I doubt a bad wheel sensor would cause the pump to stay on even with the key out of the ignition! Thanks for the advice though I'll make sure to keep that stuff clean down there, never hurts.

 

ABS Motor Relay: NA23-43-7A2
ABS Valve Relay: NA23-43-7A3