OEM ABS - Wiring Diagram and/or Service Manual?

[ManicGTI]

Hi all, my 1990 2wd Van has factory PAS - I've just noticed that the ABS warning light doesn't come on at all.

It wasn't mentioned at MOT last year and the van passed fine (legit MOT at local centre I hadn't used before), but have next MOT next week at a different place and concerned it could be an issue.  Tempted to tape over the ABS warning light just in case but that could cause more problems if they notice!

Does anyone have any service manual / fault finding guides for the OEM ABS system?  There is two diagnostic ports behind the passenger seat, but no clue on their configuration.  I assume there must be a guide somewhere on how/what to check?

Syncrosport has wiring diagram but it looks like it's for syncros only - unless I'm reading that title wrong and its just highlighting line items that are 4x4 specific?.  No diagnostic port is shown.

https://syncrosport.com/info/wiring/

Of course I will check the bulb this weekend...

[maxstu]

The ABS on my camper makes a defined noise when first pulling away after starting. A bit like release of pressure on air-brakes for about half a second. And l purposely tested it during wet weather early this year with positive results.
Is it the same on your vehicle?

[ManicGTI]

Oh really...Is it the ABS Pump under seat makes the noise?

I'm not aware of any noises coming from the system at all tbh.  I guess I was hoping there would be an equivalent for the service manual engine loom testing tables for the ABS system so I can go through it methodically. 

I'm in SW London and finding somewhere I can really stamp on the brakes hard to get it to kick in is a bit tricky.  How does it feel when it kicks in?  I don't think I've ever actually tested ABS on any car...

I have MOT on Tuesday so was planning on seeing how that goes, then refurbing the fronts sometime this summer (likely with an epytek upgrade and bigger servo). It all works 'fine' at the moment, overhauled rear drums last year.

[maxstu]

Yes. Perhaps the ABS relay has packed up. It is under the seat on the ABS pump unit thingy. And that is where the short whoosh comes from, too.

I used a very wet road surface to get the ABS to kick in. However, the braking on these old beasts is very well balanced and getting them to lock is rather daunting. It takes getting up to above 30 mph and really banging on the brake pedal. ABS pulse feels just like a modern car. But not so extreme on the actual pedal.

Remove all loose items from inside first ASK ME HOW I KNOW!!

But coming round a minor circle. Check bulb first. The ABS sign in dash pod fascia is just a bit card and easy to remove.

I suggest your MOT tester is not expecting ABS on this vehicle and the standard brake test at the MOT stayion will not introduce the ABS system. Never seen it happen on my vehicle when watching the MOT tester from viewing area.

Good luck

[maxstu]

Sorry, l should have typed ABS sign is plastic and easy to remove. ABS light should extinguish itself when revs go above approx 950-1000rpm. Is your idle very high?

[maxstu]

Any news?