164 Q4 ABS Light

[Alfamuppet]

Hi All

I have the dreaded ABS light on on my 164 - it is on and off but seems to be getting more permanent. The car has been off the road for 2 years but had just started to have the issues before I pulled the engine out to do some oil seals and the clutch etc

Its now back in and running so I am trying to see what is up with the ABS. Unfortunately I am so far not able to use the diagnostic software as it will not connect, but I have got the flash code up using the diagnostic and ground

it does the correct 1 flash then 2, 3 times meaning the start of the test followed by 4 flashes and 3 flashes, 3 times and finishes with the 1 flash then 2 flashes 3 times to indicate the test is over

so means 12, 43, 12

the manual does not list a fault code 43, does anybody know what this means??

thanks in advance

Daryl

[Alfan]

I will have to look up fault codes at another time, but I recommend this thread and the thread linked to within it:
viewtopic.php?f=2&t=2039

[Alfamuppet]

Hi Alfan

Yes I read the post earlier but the fuse does not clear the problem

Interesting that wiggling the main connector to the pump clears the light for a time, and also putting it in sport mode!

Not sure they are related but!!!

Cheers

Daryl

[AlfaWhiz]

Hey Daryl,

tho things I would suggest to check basing on my experience with intermittent ABS faults:
- check the main ABS fuse, and
- check the pump connector under the ABS cover (not the main plug, but the 6-pin connector between the ABS module and the pump/solenoids).

Both of those get loose over time and are causing trouble for me every few years/months, but cleaning the contacts and wiggling them back into place seems to do the trick. Best of luck!

[Alfamuppet]

Hi Alfawhiz

I have checked the fuse but no joy and the connectors were clean although the plating on the fuse was not great. I will change it to see if this makes a difference

Interestingly I wiggled the main connector last night with the thought it could be poor contact and the light went out. It seemed to be coming on with high revs whilst stationary and opening the passenger door! I will check the internal connections as well today thanks

I have worked for the company TE Connectivity / AMP for 27 years serving the auto/ commercial vehicle industry and know all about tired old connectors where the contacts relax over time with constant heat and vibration and the technology in the 80’s / 90’s and also the practices of tethering the harness to reduce vibration are not where they are today!

I’ll keep you posted

Cheers

Daryl

[Alfamuppet]

Ok getting some where

The ABS communicated at last with a multi ECU scan and the software from here and it indicates not connected right hand speed sensor

No other faults are found

I have been playing again tonight and have tested the resistance of the sensor and it is correct at 1600 ohms and this is read at the sensor connector and when connected at the connector to ABS unit pins 10 and 12, and on testing the continuity of the wires individually, all is ok. We then cleaned the contacts and plugged it in and the light has gone out so hope this Is a connector issue that we have solved although I may see if I can close the contacts a little. The only other issue now could be a dry joint on the header side of the connector to the PCB itself but this would persist and reconnecting would not solve it I would think.

[Alfan]

Good to know that you found some things. And it seems the error codes matches very well...

[Alfamuppet]

Thanks Alfan for searching this out that's great and confirms the software scan, its good to know you can talk to the car even without a computer!

i hope now that I have no further issues but suspect the connector has been an issue in the past as somebody had used a cable tie to try to secure it to the frame.

I will keep looking at the connector and see what I can do to improve the connection security, but at least I currently have a working pump.

what kms do you have on your Q4 now? you had over 500k last time I saw it on your signature

Cheers Daryl

[Alfan]

My Q4 has passed 550k, but I started taking at apart 2 years ago and not much has happened since... I hope to get more done this year, and will keep this thread updated.
viewtopic.php?f=22&t=1135

Connected with multiecuscan you should also be able to activate the ABS pump, to make sure that it actually works. This is something I normally do, when I am connected to the ABS system of a car, as I think it is a good thing to exercise it, in particular for cars only driven during summer, where ABS rarely is activated.

[Alfamuppet]

Just a question on the ABS control unit - it looks like it can be removed by taking out 5 screws. Is it as easy as this and can the PCB be accessed easily or is it Potted?

Was thinking it may have dry joints on the header connector, so wanted to check

Cheers

Daryl

[Alfan]

Removing the control unit is probably only the 5 screws for the black unit, one being grounding, sounds familiar. Definitely worth having a look and maybe cleaning it.

The relays are most likely soldered on, but if you can connect the tester and run the pump, you should be able to find out if any of the relays click. I seem to recall that one relay would click when turning ignition on. I had new relays put in, but not something I was going to do myself! I may have made some photos of it in a thread, but did not find it in a quick search.

[Alfamuppet]

By the way the ABS light is still on

[Alfamuppet]

Hi all

Well the ABS light is still causing issues and being completely irrational

I think it is the module itself probably with a dry joint or something. I took it off to see if it was easy to repair, but could find no way of opening it up, so will send it to an ECU specialist for testing

Using ecu diagnosis we determined the pump works as it should and both relays are good

My question is does anybody have a good spare module I can purchase as I would rather have some spare parts if possible

Thanks in advance

Daryl

[AlfaWhiz]

My advice is do not try to open the ABS module, don't ask me how I know. You can unscrew it very easily (5 torx bolts you've mentioned), but it will not come apart without getting destroyed unless specialist tools are being used and the operator knows upfront what to expect where on the inside. There is a 6-way connector between the ABS unit and the pump that unplugs easily, but internally within the module it's connected via extremely thin wires, which lead to a PCB flooded in gel. There is an access port on the module cover which is plastic-welded shut that leads to those 6 internal connections, which you would have to remove first to pry the two sides open without damaging them. All of that is precision welded (no soldier joints there). I've tried replacing the relays as well as Alfan says, but I've had no luck there - they are spot welded and I could not get them to cooperate. I would dare to say the modules themselves probably very rarely are the issue, from what I saw on the inside they are pretty much bulletproof. Also, I did a lot of research back in the day and this module is 100% dedicated one off, so no luck sourcing something similar (looked at Fiat, Lancia, BMW, other Bosch units, etc.)

Best suggestion is to try and get a good module. I've spent about 2 years of frustration with mine, sacrificed one module (trying to do exactly what you're thinking of as well - logical, but not worth it), and in the end it turned out to be a bad connection on the fuse.

Recently I had the light coming back on mine (caused some sweating and bad words), but given experience wiggling the 6-way pump connector did the trick. With our cars my best guess would be a bad connection somewhere, and unfortunately error codes won't always point to that (when my fuse connection was bad, error pointed to a bad "main ABS relay" - I've tested the relays, and they worked fine).

[Alfan]

I agree with what AlfaWhiz has written, and would rather focus on connections and wires. I do not recall how the diagnostic cabling is connected to the unit, but since you have established that the relays and pump motor are ok that way, maybe that could help narrowing down the area of interest.

I assume you found all the manuals regarding Q4 ABS on this site?

[wilco]

you might as well have a bad cable. My 97 had that when i bought it. Worth measuring resistance while moving it, especially where it moves during driving..

[krrobrock]

I am shocked this thread is active.

Well, I accidentally landed my ABS ground wire on the +12v studs on the firewall last time I put the motor in. Smoke came from the ABS pump. Not good.

I have had alternating ABS and Visco lights going on on the dash that had never been an issue. Connected the marelli tester, no comms to the ABS at all. Suggests replacing the module. I suspect it’s fully toast.

Sorry Alfawhiz, I opened up my dead module. Would have loved to read this thread an hour ago. :/

I’m on the hunt for. Used ABS unit. Wish me luck.