ABS logging issues with VCDS

[greengeeker]

I'll have to come back with more details later but I seem to be running into issues trying to log measuring blocks in the ABS module of a BRM. I've tried stopping all the background processes running on my computer (FAQ Entry 2.5) and have even tried a completely different computer with the same result: "Too many communication errors to continue"

Specifically I'm trying to log the wheel speed sensors on a BRM. It is able to communicate and log the sensors but only up to ~30mph at which point it gives me the error message and stops logging.

Wondering if others have run into the same issue in the past?

 

[jef@rosstech]

The ABS can talk to a scan tool, or do ABS functions, but not both at the same time. So for safety reasons, by design, the ABS module stops talking to a scan tool once it gets over X speed.

 

[greengeeker]

Thanks for the response Jef. Is there no way to monitor wheel sensors at say 60 mph?

 

[jef@rosstech]

Not through the data port. I guess one could back probe it and run jumper wires up to a DMM and monitor the AC voltage signal, but I don't know what voltage you should expect to see at a given speed.

 

[tadawson]

Voltage or a variable frequency pulse train? I'd think the latter . . .

- Tim

 

[greengeeker]

The ABS can talk to a scan tool, or do ABS functions, but not both at the same time. So for safety reasons, by design, the ABS module stops talking to a scan tool once it gets over X speed.

Is there no way to enter into a diagnostics mode where one can disable the ABS functions temporarily? Seems like the vcds masters should be able to make something like that possible.

 

[jef@rosstech]

Is there no way to enter into a diagnostics mode where one can disable the ABS functions temporarily? Seems like the vcds masters should be able to make something like that possible.

Windmills do not work that way!

We are a company that makes a tool that talks to the controls modules. But what we are able to do is based on what the control module we are talking to allows us to do... how the Germans designed it and this is done for safety reasons.

On older ABS systems, the module didn't kick out the scan tool. When I was in training for something, I was driving a non VIN vehicle and 3 other techs in the car. We were told that ABS modules don't work when scanning them. So we decided to test that out.... I hit 40 MPH and jammed on the brakes and skidded to a stop. Then I started to drive again... thud thud thud thud thud... 4 flat spots on the tires. Luckily this was a car that was getting crushed.