DanZ51

You may have seen my earlier post regarding a broken ABS sensor wire

http://forums.corvetteforum.com/c4-t...oment-abs.html

Well looking around I found they're a little expensive ($100 +/-) for these old cars. I also found some unusual listings for replacements, some group 88-94, others 86-94. YellowYbody had a couple of used ones for half the money so I took a chance to see if these (88-94) sensors would fit. What I found was they will fit the sides are reversed. The way the mounting tab is positioned Left sensor fits Right side and vice versa.

Here's the Left sensor that I used for the right (passenger) side.


There was a good amount (25 years worth) of corrosion in the aluminum hub that needed to be cleaned out to slide the new sensor in. I started with a brush (by hand) then ended up using a Dremel and sand wheel.


The replacement sensors are similar but the rubber grommets are in the wrong spots. A little WD40 will allow them to move. A sleeve also had to be split and removed (shown off).


Here is a comparison of the Left (driver's) original sensor with the 88-94 Right side sensor. I was a bit longer. I had nothing to compare from the passenger's side, but I don't believe there was nearly as much difference.

Here's the driver's side connector. With the replacement sensor I merely made a neat loop with the excess wire and zip tied it secure.

Hopefully this helps us '86-87 guys come up with sensors.

leesvet

Thing is,
that each sensor is oriented specifically to that wheel only. Most yr models are different as well, so there is no cross reference.
But,
you CAN get the same sensor from porche, mercedes AND a caddy if you can find one in a bone yard...wheel specific.Same yr usually. The Bosch ABS changed almost yearly so finding a donor means looking for the same yr you have in one of those 3 other makes.
Last time I came across a same yr being parted out I grabbed up 3 of the 4 sensors and damn glad I did...I've needed 2 of those since. The tips get knocked off with bad bearings and the sensor is ruined forever..

Cliff Harris

The main thing to watch for is that the "blade" on the end of the sensor has to be parallel with the "gear teeth" on the part attached to the wheel hub.

This is very helpful. The sleeving on my ABS sensors has long ago dried out, cracked and fallen off. The result of years of autocrossing and track days. I did buy some used sensors from somebody on eBay, but the idiot cut the cable and only left about 6" of wire on the sensors (no connectors).

JackDidley

This needs to be a sticky at the top of the page. Thanks. Great info. No problems with my 87 yet . Key word being yet. I know eventually I will be searching for this thread.

DanZ51

Well this was cause for concern, because in my haste (had other "projects" I should have been doing) I failed to take note of which way the "blade" was orientated.

So I just went on a little tour. The ABS light functioned normally at start up, went through it's test cycle. Then about miles down the road the ABS light tripped on "Dammit" I may have to re-orient the hold down bolt holes. I made a brief stop, then restarted the Vette. Drove about a mile (no ABS light), then made of series of ABS stops on a dirt road between 45-20 mph. Did I mention I love my C5 front brakes! The ABS functioned normally kicking on at wheel lock up, still no ABS light. Drove home another five miles, and all seems to be good (no light).

For the moment I'm calling this good. The incorrect "blade" orientation doesn't seem to be causing an problem. I'll try to put in a little more stick time, and report back if I have any other/more issues.

scorp508

I may be coming back to this thread in a few days. My ABS light comes on quite often, but not all the time. I'm suspecting a wheel bearing or a sensor wire that has gotten fragile with age and losing signal when hitting a rough spot on the road. It was a good excuse to finally break down and buy one of those J-35890 ABS testers and an ABS pin out box to do some testing without throwing random parts at it.

DanZ51

Off-hand I would believe you were right regarding the orientation of the "blade" end of the sensor, BUT so far actual road use has not shown this to be a problem. I know they are not oriented 100% "right" but I'm not sure how far they're off. I didn't even think to look until you mention it. Guessing from the pictures and what was left of the old sensors (destroyed during removal due to corrosion), I'm guessing they could be as much as 45* off but it doesn't seem to affect the ABS operation at all.

If I get to "wrenching" this winter I'll pull a sensor (or both) and actually eyeball how far off the blade is from parallel to the reluctor teeth and report back.

livingitup1963

I Need help......I am having issues with my 1987 vet's ABS..Light is on....fuse is good...Once I start the car It actually makes a pulsating noise...If I take the fuse out and drive the car..It stops like it should...With the fuse in and you brake, you can feel the pulsating in the pedal....Any ideas would be greatly appreciated...The car has been garaged for several yrs. The people I purchased it from a yr ago only started it and it has only 57,000 original miles on it...I guess I should of listened to my now X-husband....lol Him or the vet....I guess we know what I chose...

leesvet

well, the vette will probably still look good to you in 20 yrs.....thats some consolation

IIWM, I'm go thru the elect plugs and relays in the ABS control block. If its still functional it may be as simple as dirty or corroded connections giving a false signal of sorts..
beyond that I'd look at the fluid, maybe flush it and bleed the system, according to the FSM methods for ABS.

DanZ51

The ABS runs a self check after start up when you just start moving (something like 5 MPH). So that initial pulsating noise is a "good" thing.

If it's pulsating when you brake (on a normal surface - not skidding) then the ABS thinks you ARE skidding. I would check to see if there is debris on one of the sensors that is fooling the ABS computer. The problem is, from experience I can tell you, those sensors are not gonna come out peacefully on a 25 year old car. I destroyed both rear original sensors removing them.

So on the rear you would have to look into the hub from under the car, past the outer u-joint, to see the reluctor ring and the end of the ABS sensor. The front really shouldn't be the issue as they are enclosed in the hub and should be free from debris.

Your ABS warning lamp isn't staying lit is it?

pmihaltian

This is a great write-up and VERY helpful.

Can you tell us again where your purchased your new sensors along with the proper part #s, etc.

DanZ51

Got the sensors off FleaBay. Turns out it was from a CF member YellowYbody

livingitup1963

are all sensors the same on all 4 wheels? When i tested ohm 2 where putting the same amount and two where not...does this make a difference?

DanZ51

Yes all the sensors are different. What were your ohm readings, how far different were they? How do your wire pigtails look? Did your readings fluctuate with movement?

scorp508

All of them should be between 900-1500 ohms, and no two should be more than 100 ohms difference from each other.

DanZ51

I know the rules about resurrecting an old thread but this is more of a drawn out conclusion. Cliff brought up valid concerns about the Sensor "blade" not being orientated properly in relation to the tone wheel. Initially this didn't seem to be a problem, yes sometimes is would trip the ABS sensor light (then no ABS) but normally it wouldn't. And even if it did trip it would reset the next start up.

Well that got old real fast. If you enter a busy highway the last thing I want to see is the ABS light glowing at me. So when I had the Vette on stands to take care of a couple other issues I vowed to fix the Sensor orientation.

So here is the drivers side rear wheel hub stock (the ABS sensor is marked RR, remember we switched years).


Here I've removed the sensor and the cable support bracket. Note the stock orientation of the ABS hold-down.


The new orientation of the Sensor hold-down and the cable bracket. I did this a few weeks back and have since forgotten what size drill/taps I used (sorry). Because the flat surface of the hub starts to curve out near the end of the hold-down, I beveled the underside tip of the hold-down so it sits nice and flush. The cable bracket was relocated and the wire shouldn't rub on anything at normal road height.


The same process was done to the passengers side. Aluminum drills and taps nice and easy, so it was a quick process. And if anyone wonders, in no-way can I see the new bolt holes weakening the (substantial) thickness of the hub support.



Completed and absolutely no ABS hiccups what so ever.
Now we just need to compile a list of ABS donor vehicles....

Cliff Harris

I know that '80s BMWs also used the same kind of ABS sensors. They also have the same connectors. I think Volvos did too (not sure about that).

One big problem I've seen with the ABS sensors is the yellowish connectors get brittle and just crumble into small bits and pieces. I have heard that the later Bosch ABS blue connectors have the same problem. The solution seems to be to go to an AC Delco connector.

This is an ABS sensor I bought on eBay because it had both the male and female connectors. Didn't help much:

DanZ51

Interesting Cliff, I didn't have problems connectors (thankfully) but the wires themselves. They became brittle, insulation fell off and broke. Are you suggesting converting to a "WeatherPack" or "MetriPack" connector?

The salvage yards up this way a devoid of anything older than ten years so I'm not much help as far as alternative parts vehicle research.

leesvet

IIWM,
I'd find the correct gauge wire and just solder in new wire thats sleeved for outside service. The soldered joints cannot be any more resistant than the plug in connectors. Heat shrink and liquid tape should do a fine job sealing.

Cliff Harris

These things are just plain weird. If you look closely at the sensors, you'll see that there is some kind of molded black part put on after the wires were connected. There is no way to get in there and connect new wires directly to the sensors. The only option is to splice new wires to the old wires. It looks like the black part was swaged in place after everything was assembled.

I thought my wires had brittle broken sleeving and then I looked closely at the ABS sensors I got from eBay. There is some kind of rubber that is molded around the wires. That's the stuff that crumbles and leaves the wires exposed. I think the heat from the brakes causes that (my guess).

Another problem I've seen is that there is a small yellowish tan "plug" in the black part that seems to be made out of the same material as the connectors. It can crumble too: