Greetings all,

Yesterday while tooling around with the rear glass hatch solenoid (because the glass was so tight with strong hatch pistons and new weatherstripping) found that the solenoid was "sticking" so-to-speak or, that the glass has a large upward pressure causing the hatch to "bind".....

**With that said;
Facing (looking into the back compartment) the rear of the car, to the LEFT of the latch, I unplugged a relay to see if it was loose or, had a bad connection.....(Edited) - re-examined connectors at relay and not the issue...WHAT is this relay for?

Problem;
When I later started the car and backed out of my driveway, I did not hear the usual groan from the ABS self-test I have gotten since getting my car...Further, I noticed that my anti-lock brake light is on!...

This is an 88 coup, new master cylinder and bled properly...Replaced a brake line months ago and all is well there......I do not have my HELMS SM available here at this time and cannot get to it until Monday.....Does the ABS system have a related fuse in the fuse panel? I will try and plug and re-plug all the connectors to the ABS late tomorrow if I am lucky.....Also, I did a scan with an Auto X-RAY 6000 scanner and it did discover a fault in the MAF sensor relay which I will address asap......I did discover that the scanner will not clear that error code and I do not know how I am to clear it w/out a Tech 1 or 2....Can this be cleared by any other method?....Thanks in advance.

 

If yours is like my 86, fuse #16 in the fuse panel is for the abs system. AFAIK you need the specific tester to check out the abs system, I don't believe the Tech units are able to test it out. One additional thing, AFAIK when the ABS light is showing on the DIC, the brakes work it's just the abs won't work but the brakes will still function like a non-abs system.

I had an issue with mine when I bought the car with the abs system. The light on the DIC would come on for the abs system. Initially I found if I started the car and the light was on, turn the car off and restarted it the light would be off. Over time it came to the point where the abs light was on 100% of the time. I was determined to find the issue and eventually did. One day while checking it out, I rapped the relays on the abs pump with a screwdriver handle (IIRC) and the light was out on start and stayed off a few start cycles then came back. At this point, I figured my issue had to be one or more of the relay has to be sticking so I went looking for replacement relays.

In looking for replacement relays, I eventually found all 3 on ebay for a reasonable price. Know though the same relays were used in a large number of cars in that era and used the same Bosch relays in all of them. I replaced all 3 relays and have not had problem with the abs system since.

Here's info on the parts from a thread I posted previously:
I was just going against the Bosch numbers on them I wrote down from mine:
Module Relay: 0332512006 - Looks like there's another possible but would have to do a little trimming on it.
Pump Motor Relay: 0332002171
Solenoid Relay: 0332205003

I did a search on the numbers off the various units and they came up for Mercedes Benz, Porsche 911, BMW & Volvo in various 'for sale' ads, most of them having pictures showing the same units including the Bosch part numbers. Most did not always list a specific vehicle model other than the Porsche from my initial looking.

I seriously suspect the ABS pump in those corresponding vehicles are probably the same also but haven't found anything on that yet (if the parts are the same, I suspect the pump portion is the same also but that's speculation). The other thing is the wheel sensors, I'm wondering if the other manufacturers used the same ABS Sensors that were used on the Corvette? They're unavailable unless you luck out and find some used for the C4's.

Funniest thing I found though was a relay listed for a C4 typically was $40-50 where the same used relay from a Mercedes was listed for under $20 (found more than 1 at that price).

Actually I makes sense, I think Bosch was the only company making ABS systems back in that timeframe.

Update: Went back and started looking up some of the models
Module Relay 0332002171: BMW E30 ABS Anti Lock Brake Pump Relay 318is 318ic 325i 325is 325ic 325ix
Mercedes W126 W123 W107 W124 W201 relay 0332002171
0 332 002 171 | PORSCHE / AUDI / VW OEM ABS PUMP RELAY
Solenoid Relay 0332205003; BMW E30 Mercedes Corvette ABS Pump Breaking System Relay Bosch 0332205003
NEW Bosch Relay (ABS) 0332205003 BMW 34511154919
ABS SYSTEM RELAIS VOLVO 740 - 760 - 780 - 940 - 960 / BOSCH 0332205003

Possible alternative for 0332512006: 0332512007. That one has a skirt that would have to be trimmed, but first look appears it may be the same relay in a different housing.
.

Hope that helps. Good luck.

 

Thanks for the reply!

Yes, every little bit helps!...I was driving yesterday and some jerk-off pulled out in front of me and I hit the brakes hard and the car actually slid!....ugh!....Do you think pulling the battery cable or fuse would/could reset the ABS dash light?..I will look to see if fuse exits hopefully today...I have a spare pump, computer module and relays for this in case it becomes necessary....I do suspect that the "code" (ABS light) may not be able to be reset...

Found this link which may help someone out;
http://corvettebuyers.com/c4vettes/codes.htm

Also this;
There are four codes that will not display without a scan tool. Also, note that the 1986 through 1989 Corvettes will not display any ABS codes. A special test fixture is required for those models.

 

Based on my situation, just turning the car off seemed to be enough to reset. If it fails the self test (including initial powerup) it causes the light to be displayed. Worst case, pull the battery cable would definitely reset any codes. I have a battery cutoff but didn't need to use it.
If you have another pump and relays, it would only take 10-15 minutes to change out the relays, that would be a quick and easy way to see if that's your issue. There were schematics on the relays, so with a 12v source and a little wiring, it would be easy to check them out.

As far as sliding after hammering the brakes, you basically have non-abs brakes if the abs unit is not working (and it isn't when the light is on). I don't know if you're old enough to have driven non-abs cars or not. Yes you can lock the brakes up in a situation like that and go into a skid, what's the way it was. That was one of things taught in drivers ed - pump your brakes to avoid a skid due to brake lockup.

 

UPDATE -

Found the problem(s).....Wire (red power) to ABS at connector corroded off!...It may have had a crappy connection but, either way I have to get to a parts store and see if I can match it up for a replacement. Pulling the stop lights or brake light fuse shut light off.

Found a code 36 and swapped out a couple of good known relays and that did not solve the problem. So, i too a spare MAF sensor (at air cleaner) and swapped that out and all is well....Not sure if crappy connection but, as long as what I put in there works, I will wait till something else happens.

 

Based on my situation, just turning the car off seemed to be enough to reset.
wish it were that easly but not for me - however, i was typing my "update" just as your reply was posted

If it fails the self test (including initial powerup) it causes the light to be displayed.
yup

Worst case, pull the battery cable would definitely reset any codes.
yes, i know...I know i could clear codes on my other car but, wss not able to do so on vette...I forgot that I had car running when I attempted to.

I have a battery cutoff but didn't need to use it.
If you have another pump and relays, it would only take 10-15 minutes to change out the relays,
yes, that was my 1st plan of attack which made no difference.

that would be a quick and easy way to see if that's your issue. There were schematics on the relays, so with a 12v source and a little wiring, it would be easy to check them out.

As far as sliding after hammering the brakes, you basically have non-abs brakes if the abs unit is not working (and it isn't when the light is on).
yes, I was aware of that also.

I don't know if you're old enough to have driven non-abs cars or not.
ohhh yeah

Yes you can lock the brakes up in a situation like that and go into a skid, what's the way it was. That was one of things taught in drivers ed - pump your brakes to avoid a skid due to brake lockup.

 

Thanks for telling us about your fix!

My 1988 is awaiting a full replacement of all the brake lines as my brake lines developed rust on them after somebody put some kind of sealant on the ABS box junction where the lines all go in and out. I have never seen any sealant cause corrosion on steel before.

Did you have any trouble bleeding out the brakes through the ABS system? Did you have to do anything special to bleed out the ABS system?

I have never noticed the ABS system doing anything or making any self testing noises. I am not getting any codes and it braked in a straight line without skidding so I assume it is working.

Having a 1988 C4 Coupe, I recently bought a "complete, functional ABS unit" from another 1988 as I don't like not having spares readily available.

The relay for the MAF, is that the same as the fuel pump relay and the cooling fans relay?

 

Thanks for telling us about your fix!
ok

My 1988 is awaiting a full replacement of all the brake lines as my brake lines developed rust on them after somebody put some kind of sealant on the ABS box junction where the lines all go in and out. I have never seen any sealant cause corrosion on steel before.
I fixed a rusted brake line right at the abs area you are talking about...I picked up some unions and a "flexible" brake line rated for brake use and pressure the system has...I posted quite a few picts someplace here but, I may have deleted them to save space (you may have to look in forum) ....After I did that, I slipped tubing over all the lines to prevent any further rust....That goop is factory and is a bit-h to get out but do-able...The sealant would not contribute to the line failing.


Did you have any trouble bleeding out the brakes through the ABS system? Did you have to do anything special to bleed out the ABS system?
A long time ago, I totally flushed system twice and still had crappy brakes....I found the CORRECT sequence to do it and my crappy brakes came alive...I did not bleed at the abs, only at the wheels when I did my line replacement and well as my master cylinder (2 separate occasions).

I have never noticed the ABS system doing anything or making any self testing noises.
most of the time, mine would groan when I backed up.

I am not getting any codes and it braked in a straight line without skidding so I assume it is working.

Having a 1988 C4 Coupe, I recently bought a "complete, functional ABS unit" from another 1988 as I don't like not having spares readily available.
you "don't" like having spares handy?...I do!

The relay for the MAF, is that the same as the fuel pump relay and the cooling fans relay?
same for maf burn-off, maf sensor(correct name?), and fuel pump...I don't remember if same for fan.

 

The 4 codes not displayed are using the flash recovery method for 90-96 cars. The 4 codes will only be displayed by a Tech1/Tech2.

 

I attempted to upload 3 picts showing the abs plug and as well, 4 picts for the gentleman asking about the brake lines and EACH TIME it would go to 90% and stop...Something wrong with the "up-loader"...(picts are small in size fyi).

 

 

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I have been uploading to this site using small picts since I started....I don't know what has changed but, if I can't, I cant...oh well...

ADDITIONAL - As a test, I just attempted to upload an 11kb pict and site reacted the same way..Heck, 11kb' is a bit more that a darn exclamation point!...lol

 

See post #8... Re; Picts of replacement ruptured brake lines entering ABS compartment line and, how I "weatherproofed" them after I was done. Notice some of the goop that is the sealer where the brake lines enter ABS compartment (tough miserable crap to dig out).

 

Here is pict of corroded ABS power wire connector...... Will attempt to get replacement next 48 hrs. (sorry they are blurred a bit).




..

 

UPDATE;

I could not locate a replacement wire connector but, did something a bit different....I took a small single wire flat spade connector and ground down the blade sides so that it would fit into the female mate....Then, after cleaning wire, slid some heat shrink tubing onto wire, crimped spade connector onto wire and then pushed spade into female mate...It works like a charm....I then slipped the heat shrink tubing (did not use heat to shrink) over the connection and then used a zip-tie to secure both the wire and the tubing to other wires so that they remain in place...ABS issues fixed....sorry, no picts.

 

Congrats on your fix. Good feeling to get something like this taken care of hopefully permanently.

 

I was able to pull out the metal piece from the damaged connector BUT, was unable to get the solder to stick to it to make use of that connector....I will think of another way soon that will allow me to use that connector...

Now, just 2 inside door sweeps and 1 "b" pillar weatherstripping to go...I am getting water intrusion into the car because the glass is not sealing well with the other weatherstripping I put in as the new is thing, old is "flattened" out a bit. Getting the final "b" will allow me to properly set the tilt, in and out, and height adjustments of the windows.

(*section here deleted as I located issue with no glass hatch release)