Volvo 480 Club Europe

Does anyone have any information regarding th MKIV hydraulic unit,

anyone ever taken ine to pieces? inparticular the TRACS valves which i think control the two pipes at the back (only guessing tho')

cheers

Hi mate!

I have one which I removed from my car when the pump packed up in it.

Any good to you?

Its from a 95 Turbo (registered '94/M).

Steve.

possibly, do you think it will come to bits, i'm interest in seeing if it is possible for the so called tracs valves to seize if they are not used.

would like to do an autopsy on one without killing my car

alternativly is there someone in the southwest that wouldnt mind testing my blue abs controller in there car with known working TRACS , only a 30 minute job.

or perhaps do it by post

I know i should just let the whole thing go, but i ..just...cant..

alfonzobonzo wrote:possibly, do you think it will come to bits, i'm interest in seeing if it is possible for the so called tracs valves to seize if they are not used.

would like to do an autopsy on one without killing my car

alternativly is there someone in the southwest that wouldnt mind testing my blue abs controller in there car with known working TRACS , only a 30 minute job.

or perhaps do it by post

I know i should just let the whole thing go, but i ..just...cant..

Well I'm not far from Bristol (winscombe). So could test it for you if you like? I'm a bit busy for the next few weeks, but if no one else can help, and you don't mind waiting?

Richard

that would be appreciated,

if ive not got it sorted by then, which i probably wont cos of bloody christmas getting in the way

I guess they could. The pistons in the calipers seize sometimes, so i don't see why the ones in the ABS couldn't....

so i don't see why the ones in the ABS couldn't

cos they are constantly lubricated by brake fluid and not exposed to dirt or road salt?!

dont want to sound like a spoil sport but i wouldnt go near the inside of an ABS unit, there are too many things you could do to mess it up, resulting in (worst case scenario!) no brakes!!
even something as simple as scoring the surface that a seal mates against could cause a leak/failure, be carefull!

good point...

yep, guess your right about tampering with the guts of it...


what do yuo think of this? i posted a question on BBS reman forum cos from other posts they seemed to know alot about the mk1v pump....



http://cgi.www.demon.net/cgi-bin/www.bb ... 1103204170


do i not have the right kind of setup??

My pump has 4 ports on the left of the pump - 2 sticking out further than the other 2, & 2 ports at the back (all looking from the front of the car)

This guy seems to think its abit more indepth than just changing the ECU.

Thats what i said in your other thread, i think tracs cars have extra pipes.
Richards has loads of brake pipes in the way of the rear engine mounting , me and my non ABS car only has one

Excerpt from VADIS:

TRACS operation


The following example illustrates how the TRACS works when one of the driven front wheels starts to spin. In this example the front–right wheel is spinning.
When the TRACS function is actuated, there is no pressure prevailing in the master cylinder (1). The pressure needed to brake the wheel must therefore be supplied by the hydraulic pump (E). However, the pump pressurizes the entire brake system. Vehicles equipped with TRACS therefore have two additional valves (Ta and Tb) which ensure that pressure is not applied to the rear wheel brakes or to the master cylinder; one valve for the primary circuit and one for the secondary circuit.
These TRACS valves are actuated simultaneously with the pump when the TRACS function is in operation. The built–up pressure is then transmitted only to the front wheel brakes and is controlled with the inlet and outlet valves.
As the front–right wheel is spinning, the situation at this wheel remains unchanged, i.e. inlet valve (C1) open and outlet valve (D1) closed, but inlet valve C2 for the front–left wheel closes and no pressure is admitted. The value of the permitted pressure limiting valve and the master cylinder.
When the brakes are applied, and therefore the brake light switch is activated, the TRACS function is immediately disengaged and the system moves to standby mode in readiness for ABS operation if required by the prevailing conditions.
The TRACS function will also be stopped if the computed temperature of the brakes exceeds a given threshold value

The TRACS function will also be stopped if the computed temperature of the brakes exceeds a given threshold value

wow, volvo designers do actually think of absolutely everything!!!!

so thats that then i guess, the assumption on the 480 club europe site is wrong, you cant just swap the ECU's to gain TRACS

http://www.volvo-480-europe.org/cardata ... _tracs.php

Quote "It seems to be possible if you have a Mark IV ABS Computer without TRACS to replace it with a MARK IV ABS Computer that does have TRACS. You should then have TRACS on your Volvo 480."

back in with the old controller......

What happened here tho then???? quote from old thread.

Ben Harris wrote:My TRACS did work last year (not fitted as standard, but the previous owner had to have the ABS ECU replaced a few years ago, and it must have been replaced with a TRACS unit.), and doesn't need me to be braking before it cuts in. If I try and wheelspin in the wet, there's a horrible juddering as the TRACS uses the ABS to stop the wheels spinning. Saying that though, I've not noticed it doing it recently, and the roads have been very greasy around here and I've wheelspun by mistake quite a few times. I'll have to conduct a 'formal test' on the way home tonight!

You may find you need to drive the car for about 1/2 a mile before the ABS light goes out. I had a fault code on my ABS ECU due to a 'wobbly driveshaft' (don't ask!). It didn't illuminate the light, but I when I next did a diagnostic readout, it reported the code. Knowing what the cause of the code had been I ignored it and cleared it. Then, the ABS light came on and stayed on. Slightly worried, I checked with VADIS and it says the car must be driven for a short distance whilst the ECU confirms everything is OK.... and indeed, about 1/2 a mile later, the light went out.

Ben.

ben, can you shead more light on your conversion??

I was wondering too... I reckon it had tracs, but the ECU was faulty, hence replaced with a new one and then it worked again.

Quite possibly. It's a '94 model 480, but was registered in late '93.

I'm fairly certain '94 was the first year that they put bits like the MK4 ABS controller on, and SRS as standard. I was also basing my assumption that it didn't originally have TRACS on an older post where I seem to remember talking with other people with '94's that don't have it, and people with '95's that did. That's why I assumed that mine only had it due to the newer ABS ECU it's had fitted. I'll have a look at the service history, and see if anything else was added at that service, to go with the £700 ABS ECU!

Anyway - it doesn't seem to be working at the moment, as it failed my 'formal test', and just wheelspan. I'm going to have a look at it at the weekend and try a diagnostic readout and ECU reset to see if it starts working again. It did work when I bought it a year ago though, I'm certain it did as I tested it, and it kicked in several times last winter when it snowed.

Ben.

whats all the fuss about anyway?
when my wheels spin i just back off a bit with the ol' right foot!

TRACS becomes very usefull when towing that much I can tell you. Towing 1700kg of van it makes getting things moving much easier, since it slows the spinning wheel and doesn't cut power. Its a bit stupid though, since if both wheels spin, then it puts on both brakes... A little odd, but there you go

I think that may be what finnished it off actualy, since it was being used every single time I stoped at lights etc. It came back after changing the engine (reset) so maybe it also stops working is over used?

Richard

hi guys,

went down to the scrappy this morning to have a look at the modulator that the ECU came from.

it too has 6 ports, but there all at the side where as mine has 4 on the side and 2 at the back, so looks as tho there is another variablr in the equation.

do all you guys with ABS&TRACS have 6 on the side
and all with just ABS have 4 on the side and 2 at the back?

.... perhaps

Below, is a picture of the MKIV ABS unit in my 480. I'm now not so convinced that it does have TRACS any more! - If it does, it certainly doesn't seem to be working any more, but didn't report any fault codes when I checked the diagnostics readout. VADIS mentions something about having a TRACS light on the dashboard, as well as the ABS light. Mine doesn't have this. Would any other 480 owners with TRACS like to comment?



Ben.