Request: ABS Wiring Diagram - 1986
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
Request: ABS Wiring Diagram - 1986
Hi Guys,
just doing some homework before I start playing too much with a recently aquired 86, 4+3 coupe.
This car is fitted with ABS -I don't have a service manual for an Early dash car with ABS so I'm hoping that someone might be able to point me in the direction of the a wiring diagram or such.
Currently the ABS light NEVER comes on (it should at key on I beleive) and the ABS system doesn't stop the brakes from locking up. It'd be nice to try and test the ABS light too to make sure the PO hasn't had it disabled.
If its had any of the wiring messed with and its anything like how the cd player is wired up well....
lets just hope it's not 
just doing some homework before I start playing too much with a recently aquired 86, 4+3 coupe.
This car is fitted with ABS -I don't have a service manual for an Early dash car with ABS so I'm hoping that someone might be able to point me in the direction of the a wiring diagram or such.
Currently the ABS light NEVER comes on (it should at key on I beleive) and the ABS system doesn't stop the brakes from locking up. It'd be nice to try and test the ABS light too to make sure the PO hasn't had it disabled.
If its had any of the wiring messed with and its anything like how the cd player is wired up well....
lets just hope it's not
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
Just had a little dig around in the rear compartment and found a connector unpluged. Looks like for some kind of relay I would say.
4 wires going to it.
Pink & Black
Orange & Black
Orange
Black
I beleive that Pinks are normally a switched 12v and Orange is often a constant 12v.
Lets start taking bets of when this is plugged in there will be an ABS error lol
4 wires going to it.
Pink & Black
Orange & Black
Orange
Black
I beleive that Pinks are normally a switched 12v and Orange is often a constant 12v.
Lets start taking bets of when this is plugged in there will be an ABS error lol
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
Looks like I'm missing the ABS Module Relay Bosch# 0332512007 / GM# 1636973
Having just called my local parts supplier I'm guessing that this is maybe made of solid gold. I can only imagin thas the justification for the price they just gave me ($85)
It looks like this relay has a diod setup built into it. Hmm...
Does the ABS warning light get power through this relay or is this just another peice to the puzzle?
Having just called my local parts supplier I'm guessing that this is maybe made of solid gold. I can only imagin thas the justification for the price they just gave me ($85)
It looks like this relay has a diod setup built into it. Hmm...
Does the ABS warning light get power through this relay or is this just another peice to the puzzle?
Team Owner
Joined: Jan 2003
Posts: 20,324
Likes: 250
From: Summerland B.C. Canada
You can't read any ABS codes, without a rare piece of GM equipment.
Here is all I have for 86 ABS
http://members.shaw.ca/agent86/ABS%20Electrical.pdf
http://members.shaw.ca/agent86/ABS.pdf
I can't offer any real good advice, since mine has never had a problem.
Here is all I have for 86 ABS
http://members.shaw.ca/agent86/ABS%20Electrical.pdf
http://members.shaw.ca/agent86/ABS.pdf
I can't offer any real good advice, since mine has never had a problem.
Pro
Joined: Jan 2011
Posts: 580
Likes: 8
From: Clemson SC
This is the ABS brake relay made by Bosch. I had a short in my Gages circuit (pink with black wire) that was extremely difficult until I finally pulled out the ABS relay which is where the short was. Sounds like this might be your problem as well since it was unplugged. If you plug the relay and it does cause a short, you will find that the Gages fuse goes to a wide variety of things on the Vette, one of the most notable being that if it blows or is not in place, the alternator will NOT charge.
This relay is extremely hard to find. If you look at the terminals, the numbers are rearranged compared to the standard relay terminal layout that is typical now - even from Bosch. I tried all of my local and several on-line sources and never could find a new relay like this. Several of them had listings but when it came down to placing an order, they could not confirm availability even for 4-6 times the price of a similar Bosch relay.
This relay is extremely hard to find. If you look at the terminals, the numbers are rearranged compared to the standard relay terminal layout that is typical now - even from Bosch. I tried all of my local and several on-line sources and never could find a new relay like this. Several of them had listings but when it came down to placing an order, they could not confirm availability even for 4-6 times the price of a similar Bosch relay.
Burning Brakes
Joined: Jun 2003
Posts: 1,079
Likes: 1
From: Niagara Falls ON
Since this Bosch system was used on other European cars first it is possible to find parts listed under other car companies sites. I know that the exact same part numbers and systems were used on Mercedes before they were put on Corvette. Unfortunately this also means that you won't find these parts cheap.
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Pro
Joined: Jan 2011
Posts: 580
Likes: 8
From: Clemson SC
Yes, they were used by other manufacturers, and I wouldn't be surprised to find that the Mercedes dealers might be able to get one IF you can provide them with the year, model, VIN, etc. for the car that uses it. I was actually looking up the relay using the Bosch part number instead of by the car. Seemed like a good many places showed the part number in their catalogs -- just no longer available at all that I checked.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
My '86 ABS light has never come on. The system works fine. The owner's manual says the light should come on when ABS is active, but it never has (I tested it).
The definitive ABS article is here:
http://www.corvetteactioncenter.com/...abs/index.html
More info here:
http://www.corvetteactioncenter.com/...abs-light.html
The definitive ABS article is here:
http://www.corvetteactioncenter.com/...abs/index.html
More info here:
http://www.corvetteactioncenter.com/...abs-light.html
Last edited by Cliff Harris; Dec 16, 2011 at 02:46 AM. Reason: Reformatted
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
Cheers for the info guys - looks like its the ABS module that fires the test light on the DIC so I would imagin with this relay gone it would explain the lack of any ABS light.
I've been looking at this relay - my local parts place could get me one but its damn expensive, esspecially as I'm not sure what other treats are instore once its actually hooked up (errors etc).
I don't see any reason that I can't wire up the 3 diodes externally to a standard relay so I might try that route and see how I get on.
I've been looking at this relay - my local parts place could get me one but its damn expensive, esspecially as I'm not sure what other treats are instore once its actually hooked up (errors etc).
I don't see any reason that I can't wire up the 3 diodes externally to a standard relay so I might try that route and see how I get on.
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
OK just gone out to try and get a bit more time on this.
Looking at the digrams putting the White wire (915) down to ground should light the ABS lamp when the Ignition is on. It doesn't and also I get no voltage when I ground via the DVM. I do have power to the INJ1 Fuse. This pretty much indicates that the Bulb has been removed.
I jumpered what would be Pins 30 and 87 in the wiring harness. The white wire for the ABS Lamp is very briefly sent to ground and then I hear 2 relay clicks and the white wire goes open again.
The earliest FSM I have with any of this stuff in is a 91 and in that manual it would now send me to Chart B and to follow diagnosis for - Indicator light flash for less than 1/2 second. This leads me to just 3 tests that your supposed to use J35592 for.
1: Tests the circuit up to the ABS lamp
2: Tests the circuit from the EBCM and the diode on the taped up connector (white/green) wires.
3: Tests the diode itself.
Can anyone with an earlier FSM tell me if this would still be the procedure from here on?
Looking at the digrams putting the White wire (915) down to ground should light the ABS lamp when the Ignition is on. It doesn't and also I get no voltage when I ground via the DVM. I do have power to the INJ1 Fuse. This pretty much indicates that the Bulb has been removed.
I jumpered what would be Pins 30 and 87 in the wiring harness. The white wire for the ABS Lamp is very briefly sent to ground and then I hear 2 relay clicks and the white wire goes open again.
The earliest FSM I have with any of this stuff in is a 91 and in that manual it would now send me to Chart B and to follow diagnosis for - Indicator light flash for less than 1/2 second. This leads me to just 3 tests that your supposed to use J35592 for.
1: Tests the circuit up to the ABS lamp
2: Tests the circuit from the EBCM and the diode on the taped up connector (white/green) wires.
3: Tests the diode itself.
Can anyone with an earlier FSM tell me if this would still be the procedure from here on?
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
I managed to pick up an 88 manual last night (thanks Craigslist) - this has given me a much better idea of the system.
The ABS lamp gets a ground from the Solenoid Relay in its NC position (Green wire from Diode). This means that the light should ALWAYS be on while the solenoid relay is off. When the EBCM is powered up and self tests, if all OK, it powers the solenoid relay and the lamp turns off.
In the event of an error the EBCM then has the ability to ground the lamp via the white wire from the diode.
I can confirm that I have a ground on the green wire untill power is suppled to the EBCM and the Solenoid relay switches on. There is no ground via the white wire either (I do get a split second flash to ground as the relays click over). This is trying to tell me that the system has self tested and working OK.
Whats really obvious now is that the ABS Lamp has been disabled somehow - time to remove the DIC and find out whats going on.
The ABS lamp gets a ground from the Solenoid Relay in its NC position (Green wire from Diode). This means that the light should ALWAYS be on while the solenoid relay is off. When the EBCM is powered up and self tests, if all OK, it powers the solenoid relay and the lamp turns off.
In the event of an error the EBCM then has the ability to ground the lamp via the white wire from the diode.
I can confirm that I have a ground on the green wire untill power is suppled to the EBCM and the Solenoid relay switches on. There is no ground via the white wire either (I do get a split second flash to ground as the relays click over). This is trying to tell me that the system has self tested and working OK.
Whats really obvious now is that the ABS Lamp has been disabled somehow - time to remove the DIC and find out whats going on.
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
The 88 Manual has 13 pages in that section. Now that I've read the system description the diagrams make a lot more sense to me. I guess I probably should have been able to work it out just from the diagrams but it didn't "click" to me straight away.
Found my 86 Manual had this all along! Just right in the back of it - ABS section in that is 13 pages too.
Found my 86 Manual had this all along! Just right in the back of it - ABS section in that is 13 pages too.
Last edited by dan_t; Dec 17, 2011 at 08:51 PM.
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 878
Likes: 2
From: BC
Pulled the DIC and found that the Anti-Lock lamp had been removed. Put a new one in there and sure enough as I short the ABS module relay the light goes out indicating no errors. Of course I've not driven with it and I've not heard the pump yet which I beleive is supposed to self test at between 4-8mph.
