# MK4 ABS on a MK2/MK3?



## elRey (May 15, 2001)

I don't know how inegrated the mk4 abs is wiht the rest of the electronics/obd ......
Anyone know if the mk4 abs is standone (maybe early mk4s)?
Thanks,
Rey


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## Boostin20v (Mar 22, 2000)

*Re: MK4 ABS on a MK2/MK3? (elRey)*

why would you want it? I'd imagine it'd be very different, the wieght/size of the cars are very different...
my Mk4's ABS worked even after the swap from OE ECU to standalone (2000 AWD).


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## elRey (May 15, 2001)

*Re: MK4 ABS on a MK2/MK3? (Boostin20v)*


_Quote, originally posted by *Boostin20v* »_why would you want it? I'd imagine it'd be very different, the wieght/size of the cars are very different...
my Mk4's ABS worked even after the swap from OE ECU to standalone (2000 AWD).

So, if I get the ABS the correct wheel speed data, it should be able to work.
As for why? I don't race yet I find myself locking up my brake quite often. I'd feel safer with it. And I don't see how car weight ad size matters? ABS detects wheel lock up and modulates brakes to 
regain traction.
Rey


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## Boostin20v (Mar 22, 2000)

*Re: MK4 ABS on a MK2/MK3? (elRey)*

seems to me the abs brain would have calculations which assume a particular set of constants like vehicle weight etc...either way seems like a waste IMO.


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## vr6swap (Aug 17, 2001)

*Re: MK4 ABS on a MK2/MK3? (Boostin20v)*

To integrate the MK4 ABS you'd pretty much have to use the whole wiring harness, as the ABS is linked to just about every other system in the car through the CAN-BUS network. 
It's been proven that the engine management can be made to work with the other systems, but as far as I know no one has attempted a standalone ABS swap. 
If you just HAVE to have ABS, a better choice might be swapping in the system from a Corrado / Passat, and some Jettas (GLI's and Carat's) came with ABS from the factory. 
Good luck.


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## elRey (May 15, 2001)

*Re: MK4 ABS on a MK2/MK3? (vr6swap)*


_Quote, originally posted by *vr6swap* »_To integrate the MK4 ABS you'd pretty much have to use the whole wiring harness, as the ABS is linked to just about every other system in the car through the CAN-BUS network. 


Thank for your input. As for CAN-BUS integration, early mk4s did not have can-bus yet.


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## vr6swap (Aug 17, 2001)

*Re: MK4 ABS on a MK2/MK3? (elRey)*


_Quote, originally posted by *elRey* »_

As for CAN-BUS integration, early mk4s did not have can-bus yet.

I was aware of that, missed your mention of using an early Mk4 as a donor in your initial post. 
You will need the entire harness from a MK4, as the ABS wiring is integrated into the body harness and is not a separate sub-harness like on earlier models. 
The non-can bus MK4 uses a digital speed signal from the instrument cluster, and also a signal from the ECU, however I can't remember what - possibly throttle postion? 
You will also need to devise a way of connecting the Mk4 booster / master assembly to your A2 pedal cluster, as the Mk4 uses a ball / socket deal to attach the booster rod to the pedal cluster, much like an A3. 
There is an Audi model that uses, IIRC, a 23 or 24mm master cylinder, which may be the same size as the MK4 master. This may be a way around the booster / pedal cluster compatibilty issues.
Also, the Mk4 ABS unit is separate from the master, you will need to fab a bracket to mount the unit, and make all new lines. 
Sounds like a lot of work / expense because it would be. IMO you could get probably 95% as good of results for about 75% less work by swapping in the ABS system from a B4 passat. 
Or, learn how to drive without locking up the rear brakes. When you did the A3 rear beam, did you use a beam with a prop valve on it? 


_Modified by vr6swap at 5:49 PM 12-12-2006_


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## elRey (May 15, 2001)

*Re: MK4 ABS on a MK2/MK3? (vr6swap)*

I love detailed responses like this. Thank you for you time and thought!

_Quote, originally posted by *vr6swap* »_You will need the entire harness from a MK4, as the ABS wiring is integrated into the body harness and is not a separate sub-harness like on earlier models. 

I could possibly make a harness from scratch using senor and contol module connectors

_Quote, originally posted by *vr6swap* »_The non-can bus MK4 uses a digital speed signal from the instrument cluster, and also a signal from the ECU, however I can't remember what - possibly throttle postion? 

This would be a deal killer

_Quote, originally posted by *vr6swap* »_You will also need to devise a way of connecting the Mk4 booster / master assembly to your A2 pedal cluster, as the Mk4 uses a ball / socket deal to attach the booster rod to the pedal cluster, much like an A3.
There is an Audi model that uses, IIRC, a 23 or 24mm master cylinder, which may be the same size as the MK4 master. This may be a way around the booster / pedal cluster compatibilty issues. 
Also, the Mk4 ABS unit is separate from the master, you will need to fab a bracket to mount the unit, and make all new lines. 


I wouldn't try to use the booster/MC, ABS unit being separate and just
connects to the MC via standard brake line. I believe I'd have to join 
left and right line from MC into one line for back/front into ABS unit.
Fab'ing lines and a bracket wouldn't be a problem.

_Quote, originally posted by *vr6swap* »_Sounds like a lot of work / expense because it would be. IMO you could get probably 95% as good of results for about 75% less work by swapping in the ABS system from a B4 passat.
 
Interesting. What's years cover the b4 passat? This seem appealing to me.

_Quote, originally posted by *vr6swap* »_Or, learn how to drive without locking up the rear brakes. 

LOL, very true. But seeing that my wife will be driving this car from time to time, this wouldn't completely solve the problem.

_Quote, originally posted by *vr6swap* »_When you did the A3 rear beam, did you use a beam with a prop valve on it? 

The a3 beam didn't have the prop valve on it, but I retained my a2 prop valve. It's just not connected to the beam. I was toying with the thought of connect an in cabin adjuster to it and controlling it myself.



_Modified by elRey at 3:26 PM 12-15-2006_


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## vr6swap (Aug 17, 2001)

*Re: MK4 ABS on a MK2/MK3? (elRey)*


_Quote, originally posted by *elRey* »_
I could possibly make a harness from scratch using senor and contol module connectors


The wiring is pretty involved, better take a look at the current tracks in the MK4 Bentley before you get too far along. 

_Quote, originally posted by *elRey* »_
I wouldn't try to use the booster/MC, ABS unit being separate and just
connects to the MC via standard brake line. I believe I'd have to join 
left and right line from MC into one line for back/front into ABS unit.
Fab'ing lines and a bracket wouldn't be a problem.


The big A2 master is 22mm. The Mk4 master is, IIRC, 23.3 or 24.3, something like that. Doesn't sound like much difference, but there may be enough difference in system pressure(s) to cause a problem. 

_Quote, originally posted by *elRey* »_
Interesting. What's years cover the b4 passat? This seem appealing to me.


'94 through the end of '97 model year. '96 - '97 would be the cars you're looking for, they have a better A3-style ABS system than the Corrado and earlier Passats. The Passat also has a separate harness for the ABS wiring. 

_Quote, originally posted by *elRey* »_
The a3 beam didn't have the prop valve on it, but I retained
my a2 prop valve. It's just not connected to the beam. I was toying wiht the thought of connect an in cabin adjuster to it and controlling
it myself.

Okay, now that's a problem. If your car was equipped with a load-sensing proportioning valve (has a spring / lever deal on it to reduce the rear braking pressure as the suspension unloads in a heavy braking event), and you've got the valve just kinda hanging around back there not connected to the beam, that *may* be the reason your rear brakes lock up easy. 
Before you spend a metric assload of money and time retrofitting what may prove to be an A2-unfriendly ABS system to your car, at least try to correctly install a new rear-disc prop valve and see if the situation improves. 
I cut the prop valve bracket off an A2 beam, and welded it to the A3 beam I swapped into my car. 


_Modified by vr6swap at 2:57 PM 12-15-2006_


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## elRey (May 15, 2001)

*Re: MK4 ABS on a MK2/MK3? (vr6swap)*


_Quote, originally posted by *vr6swap* »_The wiring is pretty involved, better take a look at the current tracks in the MK4 Bentley before you get too far along.

barring communication with ecu or other modules, I'm not concerned


_Quote, originally posted by *vr6swap* »_The big A2 master is 22mm. The Mk4 master is, IIRC, 23.3 or 24.3, something like that. Doesn't sound like much difference, but there may be enough difference in system pressure(s) to cause a problem. 
 
I'm assuming the ABS unit does nothing more than detect differences in corner wheel speeds and then modulates needed corner brake pressures until those differences are brought back into tolerence.
That would mean it's more of an issue matching ABS pump size with caliper
sizes vs MC size. (and I have mk4 calipers on all 4 corners).


_Quote, originally posted by *vr6swap* »_'94 through the end of '97 model year. '96 - '97 would be the cars you're looking for, they have a better A3-style ABS system than the Corrado and earlier Passats. The Passat also has a separate harness for the ABS wiring. 
 
http://****************.com/smile/emthup.gif TY!


_Quote, originally posted by *vr6swap* »_Okay, now that's a problem. If your car was equipped with a load-sensing proportioning valve (has a spring / lever deal on it to reduce the rear braking pressure as the suspension unloads in a heavy braking event), and you've got the valve just kinda hanging around back there not connected to the beam, that *may* be the reason your rear brakes lock up easy. 
Before you spend a metric assload of money and time retrofitting what may prove to be an A2-unfriendly ABS system to your car, at least try to correctly install a new rear-disc prop valve and see if the situation improves. 
I cut the prop valve bracket off an A2 beam, and welded it to the A3 beam I swapped into my car. 

True, but this doesn't address locking up the fronts, which I didn't specify in the OP.
Thank you again.


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## Armagon (Apr 19, 2004)

I know this is from long ago but i attempted to try this.
Swapping a 2002 Jetta ABS into my Corrado.

Old one was not working anymore and was taking too much place.`

So i decided to install the one from MK4. All physical installations are made now.

I used brake booster from B3 passat along with the master cylinder as it was an oem Corrado without ABS.

Instead of plugging the extra holes from the master cylinder, i chose to make an adaptor which would make 2 x 10 mm hoses in 1 x 12 mm hose as you can see on the pics, the aluminum block is there for that purpose.

Now the problem is with wiring and diagnostics. I figured i will need the CAN Data Interface which lies within the instrument cluster. So i wired all together in the car to see if i can communicate with the ABS system. So far today, i was able to communicate with CAB DATA INTERFACE, with instrument cluster, but not with the ABS system.

I also installed the mk4 fron Speed Sensors and wirings :






































So as i can't communicate with the ABS module yet, any advices will be appreciate because i still don't understand why it will not allow me to communicate since i installed an MK4 cluster and wired it to communicate as it does in an MK4 car.

But as i say it, i did not try the respective instrument cluster from the same car but a random one. Next step, i will try the cluster from the same car from which the ABS system came from. Other than that, i don't see why it doesn't want to communicate.


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## chc-rado (Nov 20, 2008)

There no point using can-bus abs system from mk4 in mk2-corrado. unless you are using drive-by-wire throttle system . That how ASR works, it cuts injectors pulse width. I won't go into detail on ESP-ABS SYSTEM. your best option for your set up in a abs corrado would be 96-97 vr6 b4 passat abs system. It has EDL- electronic diff lock. Only upto 15mph. It's 4 channel system. Non canbus system. No rear protional valve. The harness is plug+play. Brake booster with master cylinder and abs module is ideal. No really fabrication needed. Only thing needed is the rear brake line and delete the protional valve bc it now integrated in abs module-valve body. Also it be plus to do front brakes to DE 11.3 setup with front lines. I did this setup on my G60 setup with plus suspension. It works awesome. Remember. Most 96-98 mk3-b4 vr6 uses same abs modules. Only common failure they have it looses rear abs signals. Mk4 abs module failures have faulty abs pump-v64. At times it not the pump. It's the abs module.


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## chc-rado (Nov 20, 2008)

Armagon said:


> I know this is from long ago but i attempted to try this.
> Swapping a 2002 Jetta ABS into my Corrado.
> 
> Old one was not working anymore and was taking too much place.`
> ...


Corrado cluster and chassis don't use canbus. Only k-wire. Also cluster doesn't use k-wire communication. Mk4 canbus abs system share canbus power-train with ECM, due to drive-by-wire throttle. Also with conjunction with airbag and instrument cluster on mk4 because the gateway lives in the cluster. Some mk4 abs don't have EDL, like basic 2.0. Some have ASR like vr6 and 1.8t. Some are ESP ABS like 24v vr6 and some higher power 1.8t.


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## Armagon (Apr 19, 2004)

thanks for you advice but once i got that installed, i am not going to remove the MK4 ABS from the car.
I had some minutes to put on it today and figured the problem.

There was one wire that was not plugged, it was the wire for the switch. Then #4 black and grey wire. As soon as i plugged put positive on it, it worked, well, it was able to communicate with the scanner.

Now, Can Data Bus can work in my corrado if i decide to make it work. It could also work on my wheel barrow if i decided to.

I wanted to get the MK4 ABS because i could get the parts easily and also because i know how it works and i knew how i could make it work properly on my car. 

The ABS comes from a TDI 2002, so with no ASR or **** like that thanks god.

I also figured that the MK4 was more technologically advanced and by the same occasion, more efficient at doing the job.

So for the records, yes i did it. An ABS system from MK4 2002 TDI Jetta WORKS ON MY CORRADO.

If anyone has questions, feel free to ask, i will be pleased to answer.


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## Armagon (Apr 19, 2004)

Since i don't want to integrate the MK4 cluster unit to the car, i will make a connector to unplug the cluster when i don't need to do any diagnostics.

So when ever i will need to plug the car, i will need to plug in the cluster and then, the scanner.


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## denongt (Jun 20, 2009)

do you have more pictueres please ?


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