164 Q4 ABS problem (warning light on)

[Porto]

Great news

The ABS light should be on when you turn ignition on and should turn off either after a few seconds or when you start the engine. I think it is mentioned in the handbook.

Did you read out error codes after putting in your repaired unit?

Of course, the ultimate test is if the wheels block or not. The pedal should kick back if the ABS pump is activated.

Last line is key, brake should kick back when braking HARD!
So, tie down all the loose stuff in your car, strap yourself in and perform an emergency stop on some lonely road (wouldn't want someone hitting you from behind, well?)

Your tires must not leave skid marks on the road, instead you feel the pedal kind of rumbling, this is the ABS regulating the braking... then you know the ABS is working just fine.

[AlfaWhiz]

Last line is key, brake should kick back when braking HARD!

Yeah, this I know, my previous car was a 156. Unfortunately, on my Q4 this is not the case, hence my question about the possibilities of debugging the whole thing.

As a matter of fact, I have studied the handbook and it is not conslusive in my opinion weather the light should come on initially or not. It does not in my case, but as said before I "fixed" (let's say) my ABS, the light was on permanently.

I'll read the codes asap (still raining today...), I wonder what might be the case and what options do I have.

Well, at lest the light is out (for now). Maybe I fixed it by breaking it, but hell... it's progress. Will post back shortly.

[Alfan]

As a matter of fact, I have studiet the handbook and it is not conslusive in my opinion weather the light should come on initially or not. It does not in my case, but as said before I "fixed" (let's say) my ABS, the light was on permanently.

I am quite sure that a car would not pass inspection in Sweden, if the ABS light DOES NOT come on when turning on ignition. This was how it worked in my Q4, until I had to 'modify' it...

[AlfaWhiz]

I am quite sure that a car would not pass inspection in Sweden, if the ABS light DOES NOT come on when turning on ignition. This was how it worked in my Q4, until I had to 'modify' it...

I agree with you, it most probably should come on initially. Then the current situation is: no light, no ABS (but the light was lit before replacing the unit).

The owner's manual does not specify that though. I've just checked in my mint-condition english version, no word of it in section B about warning lights, section C about Alfa Romeo Control, section 1.6 (just says "this warning light lights up when the system is inefficient") and also no word about it in section 5.27 (page 165 has a paragraph about the warning light, but just says "if the ABS light comes on, this signifies that the control system has identified a fault in the ABS system which will then be deactivated").

Nevertheless, I should probably try to connect and read the error codes. Otherwise, why would the light not light up all of the sudden? What could possibly change after I replaced the unit? Is there a fuse? I'm wondering how to debug it further.

[AlfaWhiz]

Quick update: plugged in the software, the previous error code was still there, that is "faulty solenoid valve relay". I don't know if it was supposed to disappear on it's own after replacing the unit or not, so I've cleared it now and I will re-check after driving a bit. There are 3 options: either it was fixed but the system does not clear it on it's own (I didn't clear immediately after replacing the unit), or it was fixed and just marked as a past error (but then why no ABS?), or replacing the unit did not solve the faulty relay problem.

Besides that, it looks as either the light bulb of the warning light has failed, or there is a problem with the feed of the light from the unit, this I have to investigate. It is very hard to believe though, as it worked just fine before replacing the ABS unit... I will pull the speedo/tacho panel, as I need access to the HVAC unit anyway.

I'm wondering where all of this is going, but I'm positive I will solve it sooner or later.

[AlfaWhiz]

I managed to remove the instrument cluster and check the light bulb. As it turns out, the lightbulb itself is not damaged. I even replaced it with another one, just to be safe - still no ABS light.

Therefore the situation is that for some reason the signal to light the ABS warning light is not reaching the instrument binacle. Maybe the ABS unit I put in is damaged, who knows.

Any ideas on what to do next? Every suggestion will be greatly appreciated.

[Alfan]

I would put in the old unit you had and see what happens. However, I think you should wait until you have found out if the error code is gone or not - that should be more important than the light, right now...

[AlfaWhiz]

My happiness was obviously premature. I went for a test drive today and the ABS is not working. I plugged in the software again and the error is still there - "faulty solenoid valve relay".

Therefore my replacement unit did not fix the problem, but has made it worse, as the warning light does not work with it. At the moment I didn't put the old unit back, as I want to test it first (if possible), since it's out anyway.

I scanned through the electrical diagrams available among the manuals on the site, but as for diagnosing the fault they were inconclusive to me, as the only end points in the procedure (test B) for this error are "replace the group N51" or "replace the relay", which since the relay is "welded"/soldered into the group N51 means basically the same thing.

What I think I will do next is gram my multimeter and check if connector pins for the malfunction warning light give anything, then at least I'll know if the problem with the light is on the side of the N51 group or further down the line.

As for the "real" problem itself, I'll probably just go through the instructions from test A and B. The problem is however that I'm not sure how I can actually check the relay itself (point A2 in the procedure, "check for correct operation of relay for solenoid valve (in group N51)"). I mean, how do I do this if I don't have access to the relay's legs? I will have to find where they attach to, but they are not listed in the pinout of the plugs. Probably there are some points too hook up to on the group itself, but which is beyond my knowledge atm.

I'm kind of lost still, any suggestions welcome.

[AlfaWhiz]

I've been doing some tests on the ABS today. So far I have this:

G272

1. Pin 1: 0V with key OFF, 12V constant with key ON
2. Pin 2: 12V
3. Pin 3: ground
4. Pin 4: 0V with key OFF, 12V constant with key ON

Now, since my ABS light is not lit, and pin 4 of G272 is 12V all the time with key ON, does it mean the light bulb issue is somewhere further down the line (connector G124)? Or should it be grounded for the light to light up?

EDIT: I've just seen that pin 4 of G272 is a signal for Viscomatic if fault is detected concerning the 4WD system. Still my question is valid, does 12V mean fault, or the opposite?

Since pin 1 in G272 is 12V with the key ON, I assume all the fuses are OK (so far I actually did not figure out where the G125 fusebox is). Also, if the F15 fuse would be blown, I think I would not have brake lights, which work just fine (the fuse is fine too).

Any ideas where to go next looking for the ABS light fault and "faulty solenoid valve relay" error?

EDIT: Reading the diagnostic procedure I find an instruction to "check for 0V (...) pin 4 of connector G272 for a few seconds", which in my case is constant 12V I think. It elaborates to just replace group N51, which does not really help.

[164 TD]

Never been that deep into it.

I'll try joining you in thinking later this week...

[AlfaWhiz]

Never been that deep into it.

I'll try joining you in thinking later this week...

Thanks, that would be really helpful.

I have found out some more, I'll redact it and post it later when I have a bit more time. Basically at the moment I have 3 units I'm experimenting with: the original one from my car that had "faulty solenoid valve relay" and working ABS light, the one I have mounted now with faulty relay and no light, and an extra unit with pull-out relays which I use to test all the measurements on (it's easier to check what is connected to what as the removable relays's connectors can be easily accessed).

[Alfan]

I will see if I can revisit what I looked at for the ABS, this weekend. It is a b.... to get to the relay connectors, so it is worth investigating what to test, before doing it.

And I didn't fix it, but that is because the pump motor is not working, so a different problem.

[AlfaWhiz]

Here's how I've tested the ABS module. I'm telling you, ABS in 164 is paper clip everything; first the flashing codes, now relay diagnosis. You need to make yourself a special paper clip tool, using which it's possible to reach under the relay and grab one of the legs relatively easily. Here's how, I'm sure it will be useful for many in the future.





I used the "older" ABS unit version with pull-out relays to investigate the connectors. Then I measured the same on the "newer" module. What found out is that the module that I have on my desk right now (the one that used to be in the car, giving the solenoid valve relay error and the warning light) has no bad connections, at least what I can measure.

On the unit out of the car, I've checked the following:

1. Pin 1 of G272 to solenoid valve relay leg 86
2. Pin 2 of G272 to solenoid valve relay leg 87
3. Pin 2 of G272 to motor pump relay leg 87
4. Leg 30 of solenoid valve relay to leg 86 of motor pump relay
5. Leg 85 of solenoid valve relay to leg 86 of solenoid valve relay
6. Leg 85 of motor pump relay to leg 86 of motor pump relay

All of the above work (closed circuit), but please have a look at the issue with measuring diodes which I describe below.

What I am not sure of are the diodes. Looking at the ABS electrical diagram I can see they are there to ensure the correct current direction. I can even measure them in my unit, measuring for resistance, but here's what happens. Instead of showing 0 resistance in the flow direction and infinite resistance in the blocking direction, the diodes show a little resistance for 1 second and then jump to infinite in the flow direction and infinite in the blocking direction. I don't know if this is normal, I am unfamiliar with this behaviour. This happens everywhere where the diode is to be expected, according to the diagram.

I will try to produce a simple diagram myself when I have a bit more time, explaining what is what when you actually look at the ABS module, compared to the wiring diagram.

Also, I'll redo the measurements on the car of connector G272, as I'm not sure about them. Actually, the pin description in the ABS wiring diagram is incorrect; pin numbers are shifted by 1. Will report about that a bit later.

As always, any help, sanity checks or suggestions hugely appreciated!

[sancho164]

Hello,
I have a problem with ABS 2Si with soldered relays. After i made one short circuit the ABS indicator turned on. The error was "Main Supply Relay". I changed the ABS Module with the two relays with 100% sure working one, but this didn't solved the problem. When i connect the diag, the same error is appearing. It's also unclearable. So, where is the MAIN relay?

[sancho164]

Guys, please help a little!

[Alfan]

I am not sure the error code you are showing, is an actual ABS part, but more a general supply relay in the car. Have you tried the self-diagnosis? Also the manual describes different things to test for, to root cause the problem.

I am only aware of the relays in the ABS unit itself, and since you replaced that with one that should work, the short circuit might have caused a problem somewhere else.

[sancho164]

I am also not sure which relay is main relay...
Today i tried selfi-diagnosis but it doesn't work. I connected pin3 on GND, but the check-lamp wasn't blinking...
Yes, i understood that the problem is not in the ABS unit, immidiately when i replaced the unit and the chek lamp was still ON all the time. Now I am wondering what else can i check. Thank you.

[sancho164]

One very expirienced guy converted the ABS directly to Bosch 5.3 from 164 Super '97. Now everything works fine, and I don't need self-diagnostic. 5.3 can be connected with all kind of diagnostics, inlc. Autocom.

[Alfan]

One very expirienced guy converted the ABS directly to Bosch 5.3 from 164 Super '97. Now everything works fine, and I don't need self-diagnostic. 5.3 can be connected with all kind of diagnostics, inlc. Autocom.

Sancho, would it be possible to get some details about what was done, in order to get this to work? That would be really interesting!

[AlfaWhiz]

I have investigated possible swap and there is clearly a problem in case of the Q4. First of all, there are so many 5.3 ABS types on the market, that it's impossible to choose... The main difference (and problem) is that most of them are for FWD cars, are calibrated for a different vehicle mass and handling characteristics and mostly use different type of acceleration sensors. In case of Q4, it's not clear to me how one would upgrade the ABS.

I have found something from Bosch Racing that is called the M4 ABS I believe, made for racing applications, with full calibration options for any car and very high quality, but you know... it's 5000 Euros.

No ABS for me until I find a way to fix mine or find another unit to swap in.

[sancho164]

One very expirienced guy converted the ABS directly to Bosch 5.3 from 164 Super '97. Now everything works fine, and I don't need self-diagnostic. 5.3 can be connected with all kind of diagnostics, inlc. Autocom.

Sancho, would it be possible to get some details about what was done, in order to get this to work? That would be really interesting!

There was a HUGE problem after that conversion!
I noticed the problem, when i decided to make an extreme ABS test.
I was driving with 60-70km/h, when applied pressure on brake pedal, as musch as I can.
Then i removed my foot from the pedal, and i felt in schock - the pedal didnt went up!
The pedal was pressed, until the car stopped to 0.
After half second, the pedal released by itself.
It was very, very, very dangerous!
If it do that on the highway, it can cause big accident.
We tried to fix it, but we didnt succeed, and now I am again with the old, but good 2Si.

The first problem, that i said in this tread, was caused by ME!
When i removed the front firelaw to install the clima, i also disconnected all the red cables from the case in front of the driver.
There is also a cable for the ABS pump main relay there. It went somewere down, and i didnt attached it when i was assembling the car.
That was the reason for the error "Main relay" in Visa Uniscan!
Now it works fine. Also saved my car from at least 2 crashes, when bad drivers crossed very bad my way on a slippy surface, and ABS let me to guide the car, during extreme stopping.

[Alfan]

Glad to hear that you didn't have any accidents!

So you have no idea why the 5.3 caused problems? I don't know if they replaced any other parts in the ABS system for that version number, I would not expect so, that close to the end of the models life span.

[alfa east]

Thank you for posting the follow-up, Sancho (although I'm sorry to hear it involved an unexpected emergency stop!).

[sancho164]

I think, that the brake pump is exactly the same on 2Si and 5.3 cars.
But there is difference in brake pipes diameter, from or to the ABS.
Two of them are with wider diameter on the 5.3 system.
We mounted addapters to solve that issue with adapters (bulgarian style ) instead changing the pipes.
I dont remember which pipes are different - from the pump to the ABS, or from the ABS to some brake calliper.
In the electronic, there was no errors, everything was looking perfect in the diag.
Maybe the problem was hydraulique.

One my friend (Grigor) with the 164 JTD is trying to mount VDC from 166 (I think 5.7 version), but he has to change all sensors with the newer type:



I warned him for the possibility to have the same problem as me, because he now has also ABS 2Si.
Conversion from 5.3 was better, but the car is 1994.

It is interesting, if somebody have ABS 2B, the first type, without diagnostic connector, to share some impressions.
I have it on my 3.0 V6, and it is a disaster. It is activating the pump on a good road, without sand, with good tyres, without any reason. It is acting, like there are no sensors and ABS ECU, just a relay for the pump. There is absolutely no logic in the work. Deffintely it has a problem
I changed it with 2Si from Super, it was very easy and the pipes was the same. But i have to change the whole wires, because the ECU on 2Si is mounted on the ABS, while the 2B ECU is near the Motronic.

[riprex]

Original ABS 2B is utter rubbish, its not even digital. It didn't work properly 30 years ago and it doesn't work properly now. I am driving my 12V QV with no ABS at all (no ABS light, but wheels locked up) and considering upgrade. But whole brake system is not adequate. I've got calipers, servo, cylinder and discs from 96 Super and considering to swap even ABS pump with harness. But even with better semi-racing brake pads - Ferodo DS2500 it stops rather leisurely. And it is the same thing for any other 164 I've drove.
For ABS light and solenoid faults - it is often caused by stuck or malfunctioning brake proportioning valve at rear subframe. Disassembling those rusty brake lines takes a lot of time, patience and rust-shock sprays but valve itself is just about two allen plugs and cleaning it inside - it has to move freely.