ABS Module - No communication

[Scooblitz]

Hello

I've been having issues for a little while with my ABS. Light is on as well as traction control.

My Z has a build date of September 1997 with the very early OBD system.

It has been plugged in to more than 7 different diagnostic tools. Even a laptop with R232 cable running windows 96 and early INPA. No handshake between car and ABS module but all other functionality is available.

Are arrows pointing to a broken module since there is absolutely no communication?

 

[colb]

Since yours is an early car I am supposing you are plugging into the under bonnet round pacman diagnostic socket?
Around 1998 they started fitting a 16pin OBD2 socket under the steering wheel as well as retaining the round underbonnet socket. The 16 Pin OBD socket will only read the engine and transmission modules, the round socket reads all modules.
Now if you are unable to communicate with the ABS using that R232 cable on early windows versions then I would suspect the module is dead from an internal error, most likely broken or dry joints inside the board. People do cut the plastic cover off and resolder the joints, there are old threads on here regarding this if you do a search. Hope that assists you in solving this.

 

[Dino D]

I’ve had this on my early car.

The mechanic with experience of these had an old snapon tool he kept just for this.

He said these early ABS units rarely fail like the newer ones.

It’s almost always the sensors on the hubs.

Changed one/two at a time but in hindsight should have just done all 4 as they went one after the other.

Been perfect ever since (4yrs or more I think).

 

[Andyboy]

I have this now and again on E36's which use the old systems. Plug it in under the bonnet and with the ignition on, push the car backwards and forwards to see what's what.

I've not yet - in 30 years - had a trigger ring. It's always a sensor or green corrosion in the sensor to car loom pins.

 

[Scooblitz]

Since yours is an early car I am supposing you are plugging into the under bonnet round pacman diagnostic socket?
Around 1998 they started fitting a 16pin OBD2 socket under the steering wheel as well as retaining the round underbonnet socket. The 16 Pin OBD socket will only read the engine and transmission modules, the round socket reads all modules.
Now if you are unable to communicate with the ABS using that R232 cable on early windows versions then I would suspect the module is dead from an internal error, most likely broken or dry joints inside the board. People do cut the plastic cover off and resolder the joints, there are old threads on here regarding this if you do a search. Hope that assists you in solving this.

Hi @colb Thanks for the reply. Using the connector under the bonnet as my 97 has no other connector.

I will need to have a look for the forum posts on this. It wont be something I would be able to do myself. I have a few other leads in Glasgow area, a former BMW master tech and a car electrician close by.

The car has 120,000 miles on the clock so it wouldn't but unreasonable to have dry solder joints.

 

[Scooblitz]

I’ve had this on my early car.

The mechanic with experience of these had an old snapon tool he kept just for this.

He said these early ABS units rarely fail like the newer ones.

It’s almost always the sensors on the hubs.

Changed one/two at a time but in hindsight should have just done all 4 as they went one after the other.

Been perfect ever since (4yrs or more I think).

It would be ideal if it was a sensor. The rear 2 sensors are 10 months old Bosch units that were replaced during the rear subframe refurb. I do have a new front sensor but it would be a coin flip as to which one it is.

 

[Scooblitz]

I have this now and again on E36's which use the old systems. Plug it in under the bonnet and with the ignition on, push the car backwards and forwards to see what's what.

I've not yet - in 30 years - had a trigger ring. It's always a sensor or green corrosion in the sensor to car loom pins.

I think I will have a go at getting a multimeter into the sensors for a test. They have been removed for visual inspection with no signs of green corrosion. Rear 2 are new so less likely to be at fault but by no means definitive.

 

[colb]

A good code reader should be able to view live data from the wheel speed sensors and I'd any duff one

 

[t-tony]

You can test a wheel speed sensor with a volt meter by disconnecting the ABS lead plug and connect the volt meter across the 2 terminals. Then spin the wheel and watch for deflection on the volt meter. Spinning the wheel causes a voltage via the coil in the sensor. No deflection means no circuit, ie. dead sensor.

Tony.

 

[Scooblitz]

A good code reader should be able to view live data from the wheel speed sensors and I'd any duff one

It's had lots of code readers plugged in and no joy. Even windows 96 INPA. The garage actually loans out this laptop and software to the local BMW dealership when they get something of this era in. The dealership last used his equipment for an 840ci. £100 for their pleasure.

If it were a sensor I'd expect that level of code reader to have picked up something. Perhaps not.

Certainly a few tests could help narrow things down.

 

[Dino D]

Sensor wise it was my front passenger side first.
The last to go was front driver side.
It was all crusty in the mounting areaso a bit of fun to get out - the sensor itself looked fine visually but they usually do.

Like so many things I’ve come to learn, it’s best done in pairs I reckon as it would have saved me multiple trips and hassle!

No code readers picked it up except the museum piece snap on tool.

This was around 120-130k miles too for me.
Interestingly on the topics of sensors - I’m wonder if the new ‘stock’ of these are inferior to the originals when fitted to the car - I replaced my crank sensor with a BMW item a few years back (original lasted 18 yrs and 100k+ miles. New BMW failed after a few years and probably 15miles).

On our other German cars 9 and 18yrs old - the niggles and warning lights are all also sensor related - mechanically all solid.