ALDL Data Line ECM / ABS

[aaaaamartin]

Hi all,

I need some help with the ALDL on my 1990 Regal.

It is equipped with the PM-III.

The M - ALDL Pin has the ECM + DASH + ABS all connected to it.

I read somewhere, but cannot remember where, the invidual stream can be selected by changing impedance on the data-line.

The ABS-Controller is lying on my bench, all hooked up to power + ignition signal, but nothing goin on on the dataline - only +5V constantly.

So anyone please have a protocol spec for that. Or at least tell me how to persue the controller to tell me it's status.

Regards Martin

Edited November 14, 2018 by aaaaamartin

[Imp558]

More often than not ABS problems are from a failing wheel bearing. 

I admire your determination but if it's a real ABS problem converting it to non ABS would be a solution.

[walterdude]

In MY opinion ABS SHOULD be disabled at the VERY FIRST opportunity!!! If not sooner!!! I absolutely HATE ABS!!

For me it causes WAY more (driving) problems than it's worth

Just my opinion... Maybe I AM old!!! My foot seems to work SO much better than that mechanical CRAP!!!

I HAD a long response ready to post... Decided to keep it to myself!!! I've read posts here from people who think it's great,,, so I'll respect their feelings... Sorry,,, i just can't agree!!!

Oh Well,,, I'll go away now!!!

Tom B...

[aaaaamartin]

I dont like it for the reason it's goin bad all the time.

 

However I experimented a bit and started a brute force attack to the Contoller.

It's device ID 0xF2 and responds to various aldl message numbers in mode 0.

Anyone has a definition for the datastream?

[vipmiller803]

Until we get 3-4 brake pedals and grow feet to match, I'll keep my abs.

I've seen one too many accidents happen at speed around here because of lack of abs. If you lose your rear traction and you still need to stop, there is simply no replacement to having individually controlled tires, or at least axles.

With that said, PM3 is well known to be tempermental. Someone recently referenced an article about going hydroboost as an alternative.

Edited November 15, 2018 by vipmiller803

[Imp558]

To me I suppose there are factors like who the driver is and what the winter weather looks like in their region.

Me, personally I prefer non-ABS and have a tough time adjusting to cars with poorly designed ABS.

Back on topic though I wonder if an MT2500 would pull brake codes?

If you suspect a problem with wiring it may be faster to just do continuity on everything.

[mfewtrail]

4 hours ago, aaaaamartin said:

I dont like it for the reason it's goin bad all the time.

 

However I experimented a bit and started a brute force attack to the Contoller.

It's device ID 0xF2 and responds to various aldl message numbers in mode 0.

Anyone has a definition for the datastream?

A PM3 datastream definition file can be found here: http://gearhead-efi.com/gearhead-efi/def/aldl/A156AM.ABS

Here's an old post from another forum about that definition file for what it's worth. " However, for the ABS computer I'm lacking a point at which I can start, so some minimal information about mode 4 is needed. The document that I used to read the ABS (A156AM.txt) only contains the specification of the mode 1 protocol of the ABS. "

 

Edited November 15, 2018 by mfewtrail

[vipmiller803]

11 hours ago, Imp558 said:

If you suspect a problem with wiring it may be faster to just do continuity on everything.

Tom might be onto something here. If you're having trouble communicating with the car, maybe a schematic and a dmm or test light are in order. Is it a passive waveform generator sensor on the pm3 cars? The sensor would have two wires in that case.

[aaaaamartin]

Hi, thanks,

I brute force addressed the controller, found out it's DeviceId to be 0xF2. That helped my figure out ~AM156~ from the aldlstuff.zip was the spec.

Wrote an application last night to map the controller response into a human readable list. Including record and playback functionality .

I will post the .net solution here for anyone to use and comment on. ASAP

Also I have spy data of Mode 4 commands. Will integrate these into the software somehow.

Edited November 16, 2018 by aaaaamartin

[aaaaamartin]

21 hours ago, vipmiller803 said:

Tom might be onto something here. If you're having trouble communicating with the car, maybe a schematic and a dmm or test light are in order. Is it a passive waveform generator sensor on the pm3 cars? The sensor would have two wires in that case.

It's just a coil.

I have the shop manual, there is schematics in there.

[aaaaamartin]

Ok,

this is without any warranty my abs tool written in C#.

This is an alpha version 1.0, it's from yesterday, so please be aware that there might be a big bug in there regarding the alignment of the data-stream.

If have not yet had the time to check, whether the computation makes sense.

Tweak the "Test.CommandLine.exe.config" to fit your needs.

To go online:

Playback: false

PortNumber: 1

Have fun,

Martin

Aldl.zip

 

Edit: Attention, the stream payload is off by one byte. Should start at index 3. Currently 4.

Edited November 23, 2018 by aaaaamartin

[Schurkey]

On 11/14/2018 at 8:38 PM, Imp558 said:

Back on topic though I wonder if an MT2500 would pull brake codes?

Mine does.  I diagnosed an open wire harness from RF wheel speed sensor on my '92 Euro 3.4, based on info from the Red Brick.  Had to splice in a batch of wire because the original wire insulation tore, and the copper conductor inside turned green and solder wouldn't stick to it.

Of course, how your MT2500 handles ABS will depend on what level of software you're using.  I am not aware of an MT2500 cartridge that WON'T do ABS...but that doesn't mean they don't exist.

Edited November 18, 2018 by Schurkey