For those with Car ABS and ECU problems;!..

Might be of interest to those who do their own car DIY.
We run, as a second car, an elderly Volvo 850 estate and apart from being quite old (1996) she still runs fine and is quite adequate for what we need.
However the MOT test the other day threw up that the ABS light wasn't behaving quite as it ought and the TRACS system wasn't quite what it should be either, and a diagnostic test showed the ABS controller was reporting that the hydraulic pump was U/S apart from other misc faults.
Much shaking of heads at the small local garage and lots of whistling thru the teeth that its going to cost yer a small fortune as a new one at the Volvo dealer will be a lot more then what the cars ever worth, so off to the scrap heap for the 850 :-(.
Thats until a web search threw up,
http://www.ecutesting.com /
Unit returned for testing and as they expected found to be faulty with all the usual faults they have. Kept informed by several texts of the progress and unit very quickly returned with a bill for 145 plus VAT. Refitted unit, cured the problem completely and car now back in service and should be OK for sometime yet.
Seems this is the new way that older cars die off now with "electronic problems" this one still mechanically fine at 150K miles not bit a bit of rust anywhere, so good result all around.
No connection apart from being a very satisfied customer etc:)...
--
Tony Sayer


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What sort of faults? Other than dodgy connections, what faults can these presumably all-digital units develop? Or are there analogue/ power electronics in there that fail/drift out of spec?
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In article < snipped-for-privacy@w31g2000yqb.googlegroup

Well if its like the PCB in our Suprima boiler its simple dry joint problems with the odd resistor being of a too low rating but then again an exchange one there has seen that working fine again:-)..
Just because its digital doesn't make it free from fault's all!..
--
Tony Sayer


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ECUs seem to be made to last, they have well built pcbs and are well conformally coated with plated through holes
The Suprima pcb, on the other hand ...
--
geoff

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scribeth thus

Now don't bite the hand that feeds you;!...

--
Tony Sayer


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snipped-for-privacy@gglz.com wrote:

I think the latter is likely to be the case.
I remember hiring a Ford once: halfway to where I was going te dashboard quit. I phoned up teh car hire, who told me to carry on. No speedo, no gauges, nada! I found an AA man parked by the road side and asked him ..."bad earth on it, hit it with the heel of your 'and'"
Voila!.
crap car.
Good advice.
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wrote:

Absolutely. First rule of electronic repair, hit it. if that doesn't work, hit it again, harder.
When you are as experienced as me you will do this without prompting :)
--
Graham.

%Profound_observation%
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On 13/06/2010 16:14, Graham. wrote:

I have one of the last of the Rover cars that I bought just before they collapsed. It has a digital clock and traffic master built in. The clock has failed to display the full time for a while now and the traffic master display is going the same way.
I know what the problem is, but the garage tell me that to get the display out will cost me an arm and a leg. I plan to get a Pifco massager on it to remove/disturb the crud that is causing the problem.
Dave
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On 13/06/2010 16:14, Graham. wrote:

Absolutely.
In our electronics lab where we maintain *very* expensive electronic and electro/hydraulic equipment, whacking things with a rubber hammer is a standard fault-finding technique.
The vast majority of faults are not fancy electronic failures. 90% are mechanical, connector, chaffed wire, etc. Of the remaining 10% electronic problems, 90% of those are PSU-related. Only a very small percentage is actual gubbins-failure.
--
Ron



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Ron Lowe wrote:

yeah. The chips never go: the connectors always do.
My In laws had a rover ..and teh windows winders packed up - he left te window open and it gotr wet.
He got a replacement from a scrappy, but it wasn't quite the same.
I opened up the old unit, and washed it in acetone to get the crud out, then went to work with contact cleaner on all the corrosion, and eventually it worked again.
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On Sun, 13 Jun 2010 18:11:45 +0100, Ron Lowe wrote:

I like that breakdown, it's about right. I'd add that a lot of the rare actual gubbins failures can be put down to the PSU throwing a wobbly or a spike/dip in the supply.
If stuff survives the first few days or weeks of regular use it will essentially last forever. Always assuming that it has been designed well, no components right up at the top of their power rating with inadequate methods of removing the heat resulting in scorched circuit boards and weakend joints after a year or three of use or simple component failure due to being under too much stress.
--
Cheers
Dave.




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Lovely sweeping statements based on invalid assumptions there
--
geoff

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Yes, at all
Your assumptions concerning good design, components not being stressed and heat transit are only ones that can be made in an ideal world
they are certainly not encountered in real consumer electronics
And I'm not sure how you equate "essentially last forever" with what parts 2 and 3 of the curve - random and wear out failures
--
geoff

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We were talking car ECUs.
MBQ
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In message

Were we fuck
"Let me show you what it followed on from
>> "hit it with the heel of >> your 'and'"
> Absolutely. First rule of electronic repair, hit it. > if that doesn't work, hit it again, harder. > > When you are as experienced as me you will do this without prompting :)
Absolutely.
In our electronics lab where we maintain *very* expensive electronic and electro/hydraulic equipment, whacking things with a rubber hammer is a standard fault-finding technique.
The vast majority of faults are not fancy electronic failures. 90% are mechanical, connector, chaffed wire, etc. Of the remaining 10% electronic problems, 90% of those are PSU-related. Only a very small percentage is actual gubbins-failure."
Nice attempt at a swerve there
--
geoff

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Not at all.
Which followed on from the OP. I'll let you lok up the title.
It was a good generalization anyway, not restricted to car ECUs in any way.
MBQ
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geoff wrote:

The other good one is a can of freeze spray.
Any area of the board that creates or clear a fault with application of freezer, is almost certainly suffering from a dry joint..
I resoldered ALL the eyelets - over a hundred - that were the substitute for plated through holes - on one telly.
Fixed all the problems that banging it cured. That was after resoldering half a dozen ID'd by freeze spray fixed SOME of the problems.

Totally my experience as well.
However the ones that I used to get handed to me were a skewed sample: they were the ones that could NOT be fixed by such techniques.
And were far and away the most interesting.
I recall one, which was a shorted polystyrene capacitor. Solder bath had actually melted it internally.
Showed up by prodding it.
Another power transistor failure was due to getting hot and the actual lead out wire on the emitter expanding enough to short to the base..I sawed it open and could JUST see where a microspark had welded the base to the emitter. Completely off target spot weld on the wire, that JUST passed testing, but failed the first time it was put in a unit.
Other nasties are digital timings and propagation delays..Yuk. stuff that statistically mostly works until you get a hot (or cold) day, and a bunch of all out of spec one way.
Conservative design and soak testing is the way you get round this sort of stuff.
You HOPE that you have put the unit through worse than it will ever get in service.

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On Mon, 14 Jun 2010 19:49:22 +0100, geoff wrote:

Tin whisker growth in germanium transistors? ;)
Actually chips can and do fail after a period of working perfectly, as the stresses of thermal cycling can break the welds on the fine wires connecting the actual IC to its external pins.
SteveW
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Steve Walker wrote:

No, that's unusual, especially in 'proper' packaging, because they are not 'tight'
Normal CHIP (as opposed to package) failure mode is dopant migration, causing the semiconductor to become less of a semiconductor: that's happens in a few seconds at 200C, a few hoursr at 199C..a few days at 198C..you get the picture. That and crackled seals leading to chemical poisoning are the two main causes of ageing.
I've never had a bondwire actually come off.

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