Brakes: Another ABS thread.....

[Luxobarge]

Originally Posted by El Padrino

The output I got wasn't what I was expecting. The codes came out in hex. Do they need to be translated to the Volvo DTCs via the jonesrh.info website? I was hoping it would do a scan and the fault codes would come up just like that. Obviously there's more to it than that upon first impressions. Will do another scan later for the ABS code information.

Yes, that's what I thought at first, but I think that's just the program displaying the scanning routine that it is running. At the end there's a box that says something like the results are displayed at the top of the main screen, so if you escape out of the screen with all the hex and go back to the main screen, the codes are displayed in plain text. I probably haven't described that very well, but have another go and see if you can see what I mean.

[El Padrino]

Originally Posted by Luxobarge

Yes, that's what I thought at first, but I think that's just the program displaying the scanning routine that it is running. At the end there's a box that says something like the results are displayed at the top of the main screen, so if you escape out of the screen with all the hex and go back to the main screen, the codes are displayed in plain text. I probably haven't described that very well, but have another go and see if you can see what I mean.

Hi Luxobarge, I did another scan and got a summary this time. Thanks for that tip. This is what came up for the ABS:

COMBI has 1 DTC: 02

CI-221: Vehicle speed signal missing [bad ABS module solders?]
[+ click to view more]

ECU 29 (ECC)
09171635 P/N Part Number
001 H/W Rev.
09442458 Software
001 S/W Rev.

So it seems it's the ABS module. It was rebuilt back in Jan 2023.

Other codes that came up:

ECC has 2 DTC: 27 37

ECC-231: Passenger Side Temp damper motor position sensor Signal High

ECC-414: (inlet)Fan motor passenger comp (interior) temp sensor, Faulty Signal

ECU 2D (VGLA)
09459266 P/N Part Number
A H/W Rev.
09459267 Software
A S/W Rev.


M4.4 has 1 DTC: 78

EFI-311: Engine RPM high for too long while no Vehicle Speed [see www.volvopedia.de/index.php?title=EFI-311]

ECU 2F (Power Seat Right)
09174906 P/N Part Number
004 H/W Rev.
09174907 Software
011 S/W Rev.

[Luxobarge]

Update: So a few more days, and a few more instances of the same two codes being generated, 313 and 314, usually together but on one occasion only one of them - an interesting occurrence given 4x4's suggestion that one of them is a "generic" code. This suggests to me that it's bad voltage being supplied, or a bad earth or somesuch.

So having looked at the wiring diagrams there's an earthing point on the inner wing just at the corner of the air box near to the coil which is apparently directly connected to the ABS system. So today I had a few moments in between rain showers to have a look at it, thoroughly cleaned it up and re-tightened, then went for a drive. On the way back the ABS light was on again, so it isn't that.

I've already been inside the ABS unit and done the soldering thing, but I think I need to go back in there and do it again, perhaps more thoroughly this time, and in the knowledge of exactly what pins I'm especially interested in.

By the way, on other threads I've indicated that the main power supply to the ABS unit (and therefore a prime suspect) is the little black (or white) plug that sits next to the main ABS multiplug. This is wrong, this plug is simply for the ABS motor on the pump itself, and therefore probably has absolutely nothing to do with our fault. Sorry if I've mislead anyone. I can confirm that the main power feeds and earths come onto the ABS unit via the main multiplug, on pins 25&9 and 24&8 respectively. I shall be paying these especial attention when I get it out!

Not sure when I'll get a chance to do this, but will update here.

Cheers all

[Luxobarge]

OK, so today I had a rare combination of time and motivation to get on with this fault, so I removed the ABS module and had another go at soldering the pins on the PCB. Now here's an odd thing, normally I'm pretty observant and thorough when I do a job, but this time I noticed that the entire surface of the ABS PCB is covered in a kind of clear jelly stuff, and it was clear that when I'd been in there before I had not removed this from the part of the PCB that I want to work on. How on earth I thought that I'd be able to solder properly with this jel on I have no idea, I must have had my stupid hat on that time. So this time I removed the jelly stuff, made sure it was scrupulously clean with a stiff brush, and had another go at re-soldering. This time I used an illuminated magnifying glass on a stand (courtesy of my wife's sewing equipment - thanks love) which helped see exactly what I was doing. Now I'm not sure, but I do think that I could see small rings of cracked solder around some of the pins, and what's more they were in the vicinity of the rear sensor feeds which ties up with the codes I've been getting. I did them all anyway, with particular attention to the main power feed pins, and put it all back together again. By the way to answer a previous question, yes, the pins are clearly numbered in the black plastic socket, so quite easy to know where you are with them.

I also removed and cleaned the main battery to body earth point as it looked a bit crusty, but I'm not sure this will have had anything to do with my fault.

Took the car on a decent test drive, and no lights so far. It's way too early to tell of course, but at least I know I haven't introduced a fault with some cack-handed soldering or some other silliness, so that's all good.

Previously it was putting the light on every other journey or so, so hopefully in a few days I can build some confidence that it's fixed, I've still got this horrible feeling I'm going to be back on here before long saying the light's back on, but so far so good, time will tell - that's the problem with intermittent faults isn't it?

Not too hard a job to do by the way, slightly skinned knuckles getting the old unit out (removing the air box helps a lot). Important to have the correct Torx socket, and a tiny 1/4" ratchet head was invaluable too. Also useful was use of an LED head torch - mind you, that's useful for pretty much any job I reckon. The illuminated magnifying glass helped a lot too, plus the usual spadefuls of patience and time.

Thanks all - I'll post back with how it goes of course

[ITSv40]

Originally Posted by Luxobarge

OK, so today I had a rare combination of time and motivation to get on with this fault, so I removed the ABS module and had another go at soldering the pins on the PCB. Now here's an odd thing, normally I'm pretty observant and thorough when I do a job, but this time I noticed that the entire surface of the ABS PCB is covered in a kind of clear jelly stuff, and it was clear that when I'd been in there before I had not removed this from the part of the PCB that I want to work on. How on earth I thought that I'd be able to solder properly with this jel on I have no idea, I must have had my stupid hat on that time. So this time I removed the jelly stuff, made sure it was scrupulously clean with a stiff brush, and had another go at re-soldering. This time I used an illuminated magnifying glass on a stand (courtesy of my wife's sewing equipment - thanks love) which helped see exactly what I was doing. Now I'm not sure, but I do think that I could see small rings of cracked solder around some of the pins, and what's more they were in the vicinity of the rear sensor feeds which ties up with the codes I've been getting. I did them all anyway, with particular attention to the main power feed pins, and put it all back together again. By the way to answer a previous question, yes, the pins are clearly numbered in the black plastic socket, so quite easy to know where you are with them.

I also removed and cleaned the main battery to body earth point as it looked a bit crusty, but I'm not sure this will have had anything to do with my fault.

Took the car on a decent test drive, and no lights so far. It's way too early to tell of course, but at least I know I haven't introduced a fault with some cack-handed soldering or some other silliness, so that's all good.

Previously it was putting the light on every other journey or so, so hopefully in a few days I can build some confidence that it's fixed, I've still got this horrible feeling I'm going to be back on here before long saying the light's back on, but so far so good, time will tell - that's the problem with intermittent faults isn't it?

Not too hard a job to do by the way, slightly skinned knuckles getting the old unit out (removing the air box helps a lot). Important to have the correct Torx socket, and a tiny 1/4" ratchet head was invaluable too. Also useful was use of an LED head torch - mind you, that's useful for pretty much any job I reckon. The illuminated magnifying glass helped a lot too, plus the usual spadefuls of patience and time.

Thanks all - I'll post back with how it goes of course

Excellent write up.

I'm fortunate that I have never had to venture inside the ABS unit, so can only imagine what it looks like. Do you think the jelly like substance was a factory attempt to apply some preserving substance to reduce future corrosion - such as Vaseline - or is it a case of the components corroding and making the jelly substance - rather like a battery left in a remote, or similar, well beyond its useful life.

Hope it is sorted as intermittent faults are extremely frustrating.

[Luxobarge]

Thanks mate! No, the soft jelly substance was definitely intended to be there, and yes, I should imagine that it's factory applied to prevent any kind of corrosion or degradation of the PCB tracking and components. I suppose I could have lathered it all in a clear coat of silicone sealant when I'd done, but to be honest the unit is pretty well sealed anyway, I'd doubt I'd see any corrosion in there in my lifetime. The inside of the ABS unit looked totally clean and "as new" to look at, it's just that we know those sneaky solder joints can still lurk there, and need to be dealt with.

Just been on another 2 short trips and still no light - fingers crossed!

[Martin Cox]

The soft jelly-like coating is a conformol coating intended to protect the PCB against damp, dust etc. More information for the curious.

https://en.wikipedia.org/wiki/Conformal_coating

Martin

[Bob Meadows]

Sometimes the jelly-like substance can be peeled back for the soldering and then pressed back into place:~

On a previous post relating to doing the soldering the author named the substance- from memory it is gel to keep moisture away from the terminals.
Memory fades here on what the correct name is- but apparently still available.

I used a light coating of GT85 and all fine to date (see my previous post regarding opening the box the easy way)

From my experience Luxobarge I would think that you have solved the thing!
Good luck.
Bob.

[Tannaton]

I'm going to join this thread as arriving at work (50 mile trip) in the C70 yesterday there was some ABS noises and then ABS/Antiskid lights. Coming home it set off okay, but then ABS & Antiskid lights and then after a short while the red brake warning light (reminded my of the "Three Amigos" from my Land Rover days....).

Got home and switched off and on again and the ABS light hasn't reappeared but I now have an EML light on? ABS is triggering over speed bumps so I'm fairly sure there is a cracked ring, dodgy sensor or wheel bearing involved.

Anyhow I'm going to get VIDA out and read the codes later and will keep this updated.....

[Baffler]

Originally Posted by Luxobarge

Just been on another 2 short trips and still no light - fingers crossed!

Indeed🤞

Great write up, Luxo, and glad to read you're feeling yourself again!