ABS/ Traction Control

[zimkip]

G'day all, I'm new to this site & hopefully I'm going to find a viable solution to my problem, which is as follows: In January I bought a 1996 model Volvo 850 GLT, on purchase, the the ABS & Tracs Control lights were lit up whilst driving & have remained so since, except when the outside temperature drops below -2c. When I queried this with the seller, he said that the problem existed with the right rear wheel, but was not altogether serious. After a bit of online research, I bought an OBD2 scanner with the idea of tracking down the fault, however, after connecting the scanner the only codes that showed up all related to a timing problem & a too rich mixture, nothing regarding the ABS or Tracs Control. I can only assume from this that the scanner is only generic code capable & not able to read Volvo specific codes. Today I found an online site that offered direct realtime access to a verified Volvo mechanic/specialist, but they wanted £43 just to address my question, which I thought was ripping the bottom out of things. I have a theory that the problem originates in the wiring harness on the wheel specified, I reached this conclusion because of the weather temperature variation affecting the dashboard lights i.e. the metal contacts contract with the cold, thereby establishing a connection. The ABS system still works perfectly despite the warning being lit up.Can anyone offer me some advice that won't break the bank & will the fact that the warning lights are on affect the car's chances of passing it's MOT, which is due now?

[Wobbly Dave]

most common causes of ABS faults are either the ABS ECU or the reluctor rings. The sensors themselves have no contact parts (it is done by induction). If teeth are missing from the castlelated reluctor rings or the rings are cracked this can lead to an out of range signal.

The other most common cause is dry joints on the PCB itself. I have personally repaired over 200 units.

Depending on the age of your 850 the ABS ECU is usually slung underneath the ABS pump itself.

http://www.vpcuk.org/forums/showthread.php?t=224

you can avoid MOT issues by removing the bulb - however this will not resolve the problem!

[t5 stealth]

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you can avoid MOT issues by removing the bulb - however this will not resolve the problem!

i think the bulb lighting up is part of the mot,it has to come on,and go off,

and most of the abs ecu probs iv seen usually come up with o/s/r speed sensor...it usually isnt the sensor,but an ecu fault...
but wobbly dave is probably the best man to see about the ecu.

[deathrider311271]

i have an ABS/TRACS ECU and pump for sale if interested

Simon

[woz]

[QUOTE=t5 stealth;519759]i think the bulb lighting up is part of the mot,it has to come on,and go off,
QUOTE]
Correct - thats persactly what Mr Mot told me as he wrote out my fail sheet.
Fault was actually due to a blown bulb.

But they doo have to see it light up and they do have to see it go out.
Mr Wobbly is an expert on the ECU, but I suggest you get the codes first - there's no point in fixing teh ECu if it aint broke - you still have the cheaper bits to attend to as well.

W

[Wobbly Dave]

i think the bulb lighting up is part of the mot,it has to come on,and go off,

and most of the abs ecu probs iv seen usually come up with o/s/r speed sensor...it usually isnt the sensor,but an ecu fault...
but wobbly dave is probably the best man to see about the ecu.

There is no check in the MOT for the ABS dash warning bulb or any other warning bulb. I have assisted on countless MOTs & it has never been raised - however if your warning light was on during the test - odds are the MOT tester is going to notice.

I am not advocating this method as it clearly impacts on your safety & the safety of other road users.

[t5 stealth]

[QUOTE=Wobbly Dave;520113]There is no check in the MOT for the ABS dash warning bulb or any other warning bulb. I have assisted on countless MOTs & it has never been raised - however if your warning light was on during the test - odds are the MOT tester is going to notice.

if you say so

[zimkip]

[quote=woz;519963]

i think the bulb lighting up is part of the mot,it has to come on,and go off,
QUOTE]
Correct - thats persactly what Mr Mot told me as he wrote out my fail sheet.
Fault was actually due to a blown bulb.

But they doo have to see it light up and they do have to see it go out.
Mr Wobbly is an expert on the ECU, but I suggest you get the codes first - there's no point in fixing teh ECu if it aint broke - you still have the cheaper bits to attend to as well.

W

Yep, that is the way I see it too, but where do I find a scanner at a reasonable price that will be capable of reading the Volvo specific codes? I have reason to believe that this particular model is not completely OBDII compliant, going by what I've picked up on various forums.

[t5 stealth]

i think your best bet would be to try your local garage or at the worst your local volvo dealer to get it plugged in as not many places have equiptment to read the 850.
if you can get fault code read it may save you a few quid in the long run,

[woz]

There is no check in the MOT for the ABS dash warning bulb or any other warning bulb. I have assisted on countless MOTs & it has never been raised ....

Wish you had assisited at mine thenMr W. Deffo failed for ABS light failing to light up when ignition turned on. On the bright side (doh!) twas a great opportunity to replace 5 other bulbs gone behind the dash while the top was off.

Had ECU codes read today (Helliker in Bristol, £35) recommeded by Cartech who have been servicing Lusty for last 100k.

One code - intermittent fault on N/S ABS sensor. Wonder if it was a waste of time soldering the sod up?

Still it was an interesting project.

WAF

[t5 pete]

Myne failed due to the light staying on i said to the tester i bet most people just take the bulb out to which he replyed no i have to see it light up and wait for it going out to make sure the abs is functioning correctly.