Help! No ABS MarkIV system.

chris1roll · Post by **chris1roll** » Wed Mar 26, 2008 7:29 pm

1995 2.0 litre Auto, Mark IVABS unit.

Ok, normally this wouldn't be quite so urgent, but the tax and MOT are BOTH out on Monday, if it was just the MOT i'd push it on a bit

but the car WILL fail like it is, and Amy needs it to get to work.

Basically, activated the ABS, which functioned normally, came to a halt, and the ABS light came on and stayed on.
Have tried disconnecting battery for an hour, to no avail.
The pedal no longer pulses or "ticks" when you turn on the ignition, and obviously the ABS doesn't work (brakes actually feel better though!)
I have read the diagnostic port and got code 4-4-4, which is apparently, "no power to valves in hydraulic unit"

So, there is the possibilty of this just being a fuse or relay stuffed up, but I don't know where to look. The fuses in the fusebox are fine.

Now, I did have ahem SIDAV on my PC, which unfortunately died a few weeks back, i unearthed the discs, and disc one has a whacking great scratch on the outside edge. I managed to get it installed and working (FYI it will work with Vista) howver, guess which parts must be in the scratched section - thats right, the 400 series brakes section!!

Does anyone else have a copy they could look at for me? there is a section dedicated to this trouble code but I can't read it!

Thanks,
Chris

chris1roll · Post by **chris1roll** » Sun Mar 30, 2008 5:43 pm

Ok, so I'm back in mu time machine, however, the explanation is "this code is stored when the power supply to the solenoid valves is missing"

Dammit, I knew that! the code title makes it kind of self explanatory really! It then tells you to plug the car into the VCT2000 computer. errr....can't do that.....

I also discovered that its stored another code - 4-4-2 which is Pump pressure low. The recommendation for this is to bleed the brakes. So we have bled, and we have bled and we have bled. That has made absolutely no difference either. However I did manage to kick about half a litre of used brake fluid across the workshop. Thinking about it now, obviously the pump pressure is going to be low as it isn't doing anything.

I've had the combined relay underneath the ABS unit off, and fundamentally theres power getting to where it should be, and resistances as they should be . However, that doesn't mean its working entirely correctly, there's about 20 wires going into it, like a second mini ECU.

So, I'm stumped, oh well, its going to Formula cars for the MOT tomorrow, so they can plug it in and have a look.

guitarcarfanatic · Post by **guitarcarfanatic** » Sun Mar 30, 2008 5:56 pm

Wire the abs bulb to the oil pressure light and forget about the abs?!!

Saying that though, I've had the ABS goign a couple of times recently in my Saab so I would probably miss it if it broke. I guess formula cars will determine if it's worth fixing or not though as they will be telling you the cost of repair!

chris1roll · Post by **chris1roll** » Sun Mar 30, 2008 11:13 pm

Well its a very clean car with just 92k on it, full Volvo service history with Taunton Motor Company, part leather, info centre, and a private plate we really ought to get round to selling, but can't now without an MOT etc, so it would only get changed if the cost of a complete ABS unit cost more than I could replace it for.....

I had considered the ABS bulb trick, however, ummm, along with it being automatic, i think the ABS might be a good thing on this one.
(that was tactful eh?)

Will find out tomorrow - MOT is till booked, need to know what else needs doing anyway, so afterwards I'll get them to plug it in and have a look. they let me take it away and repair if its something I can do myself, if its not a long job I might just get them to do it to save tearing up and down the M5.
Still get free retests!

Trust bastard electronics to make life difficult again.

chris1roll · Post by **chris1roll** » Tue Apr 01, 2008 6:02 pm

Well the ABS light is fixed, it _was_ that combined relay underneath the unit. They've fitted a second hand one for me, as I don't have spares for that version.

I've just fitted a new steering rack (3 hours, go me!!

) rear numberplate and one orangey-er indicator bulb, and once I've changed the special automatic subframe bush (difficult since someone snapped our 6inch record vice

so formula cars are pressing it in for me if I take the wishbone in) then we are back in business!

So anyway, I hope this might help someone else with the temerity to use their ABS