19 ABS system

[|sAs|]

My cabrio has a (I think) Bendix ABS system. The long term plan is to ditch it and go with a normal servo assisted system with big brakes (Peugeot Brembo's up front with Clio 1x2 discs and Laguna I 2.0 rear calipersand discs, most likely a Laguna master as well.) but in the mean time I would like the ABS system to pass MOT equivalent.
As of now, almost always when I start the car the ABS light stays on, sometimes however it goes off. Quite often when it has stood overnight the light goes off but stays on after subsequent starts during the same day.
I'm thinking that the sensors and targets are fine, otherwise the light would go off and back on as the car starts moving.
When I'm turning the key I can hear it for a few seconds as it builds up pressure and it stops after a short while, so that seems to be working as well.
Can a generator on it's way out cause these issues? I have no indication that its on its way other than windows move slowly, charging light goes off though and never flickers, even when maneuvering all windows at once.
Any ideas? @DaveL485 maybe?

 

[DaveL485]

If the light comes on at startup and stays on all the time, its normally a sensor down.

If the light comes on at startup and goes out on engine start, then comes on when driving its normally targets.

 

[|sAs|]

If the light comes on at startup and stays on all the time, its normally a sensor down.

Since it goes off sometimes and stays off until I turn off the engine it is likely a sensor with dodgy wiring? Sometimes it comes on during driving, but that's quite rare actually.
What sensors should I be looking at and where are they located?

 

[Neal R19]

I have a vague bell ringing in my head about the sensors on the Bendix system. If I'm remembering right, unlike the Bosch system they are hard wired to the ABS system loom and can't be easily unplugged? The sensor would probably break in the process of removing it from the hub/axle anyway.

In all honesty Bendix ABS which flags up an intermittent fault would have me shitting my pants. Borrowed time tbh.

 

[DaveL485]

Do you ever hear or feel the pedal pulsing/ABS operating without the wheels locking? ie, under normal braking?

 

[slgreavett]

It's been a while since I've done an M.O.T in England, but grounds for a failure are clear cut. I don't remember the abs being a test category. It was more about the ability of the breaks to pull you up.
The light on the dash is a system self test, if all is good the system is good to go. If stays on its got a problem. If it stays on after start up, I would be checking only static parts, sensors, pressures etc. If it comes on when you start rolling then it is almost always wheel sensors, gaps etc. Personally I would go to your local M.O.T station and ask to see the testers guide book for reasons to fail. Light on I think is a failure, (been a long time though) indicates system not working. Light off (abs not fitted or not operational). The car still has its primary brake system. A lot of older cars had abs as an add on system to their brakes, meaning it didn't alter anything until locking up. Later models it was part of the braking system where the abs pump and accumulator acted as the servo/booster. And if that didn't work then you virtually had no breaks. Personally I like things working as they should, but if it's a question of getting a car on road vs an unnecessary repair. I would be taking the bulb out! For test purposes only of course. Mot men can only fail your car on exactly what it says are grounds for failure in the testing book. If it's not in the book they cannot fail it on their own professional opinion. If you lodge an appeal against mot failure, you will win as long as your failure is not written in the book. For example, you could fail a tyre for being bald on the outer edge, but not on the inner edge. Or if you screeches a crack in it in the wipers swept volume it's s fail. Simply change the wiper size to a smaller arm which excludes the crack in its wipe, it's a pass. Whether the mot man likes it or not. He cannot fail the car, he can only issue you an advisory.

Like I say, it's been a long time, and the test has probably changed, and I'm out of touch, but it was always drummed in to us testers it was supposed to be an impartial test, hence the reason you could test your own car.
Sort of ended off topic didn't I! Whoopsie!!

 

[slgreavett]

Forgot to mention that older systems used to see the vehicle move over 5mph I think it was to see thehub sensors before the light went out. Newer abs systems it would come on if there was a problem with a wheel sensor when you started to move. So if it's on and stays on when you move on an old system it could still be wheel sensor related. If that makes any sense!!??

 

[Neal R19]

A lot of older cars had abs as an add on system to their brakes, meaning it didn't alter anything until locking up. Later models it was part of the braking system where the abs pump and accumulator acted as the servo/booster. And if that didn't work then you virtually had no breaks. !

In this case it's the other way round. The Bosch system as fitted to later 19s is a piggy-back system. If it goes down it's no big deal, the brakes continue working no problem. The earlier Bendix system as you say is a big problem if it decides it's had enough.

 

[|sAs|]

Do you ever hear or feel the pedal pulsing/ABS operating without the wheels locking? ie, under normal braking?

No, nothing like that.
I'm in Sweden so it falls under different jurisdiction and rules regarding MOT. Perhaps I should have written yearly test/inspection instead, but I used MOT as it is a known term here.

My dad booked the car in for this years test and left it there, so wasn't present during. The tester mentioned that it felt a bit strange during the braking test (I don't think any lights were on at the time). When you first press the pedal it seems to have low braking effort but once you press a little bit more it is a face to the windshield moment. The brake test values were excellent with about 2.6 on the fronts and 1.8 or something at the rear which is the highest numbers I've seen on all my cars (Megane not tested yet as it is too new).
I've noticed this behavior when driving as well and sometimes the braking gets a bit on the hard side, but I have no worries that they won't work even when ragging it through the round-abouts where I live..