That X2/50 engine/gearbox earth strap - again..

[Steve928]

Thanks for your input Nick it is, as always, appreciated.

 

I have ordered yet another a new earth strap anyway, this time in flexible copper welding/starter cable as per your earlier advice. The one that I fitted came from the local auto-electrician and appears to be steel braid but is I guess still unlikely to be the problem this time around even so.

 

I'm also going to clean and remake the 3 earth points that are beneath the NS headlight: there are 3 wires from the loom going to earth here. Could be just for the lights, or even a fusebox earth perhaps - I don't know..

 

I did have the engine bay fusebox swivelled-up the last time and I removed the 2 or 3 large multi-plugs and gave them a cursory inspection, but I will go back in again with a fine-toothed comb and inspect each wire individually as you suggest. It was all clean and dry down there.

 

I'm pretty sure that no fuses are blown because the engine will start and run sometimes. Having dragged the van out of the lane yesterday behind the neighbour's Navara, I went down this morning and it started first time and I was able to drive it around the house to its normal parking spot whereupon the engine promptly cut out again after ticking-over for 20 seconds or so.

 

My initial thoughts (prompted by what the AA man found last time) is that the relay that supplies the ECU is sometimes not being energised or is dropping out. This is in that same fusebox so it seems that the culprit is in that area somewhere; bad contact, weak earth, broken wire etc. or even just a bad relay I guess.

 

Thanks again and I'll let you know how I get on.

Steve

[colin]

Just be on the safe side I would take off top of air filter and check for mouse damage, I´m a bit paranoid about that after the problems I had.

[Steve928]

Well Nick it looks like you're going to be spot on in your diagnosis.

By the time that light stopped play today (having cleaned and checked every earth connection I could find) I've discovered that the fault can be cleared by pulling down hard on the wiring loom where it disappears into the underside of the fusebox.

 

- Ign. turned on, immobiliser light on, nothing running, dead as a dodo.

- pull down on the loom and the pumps start up. Immobiliser light clears, glowplug relay engages.

- release it and all goes dead again..

 

So tomorrow, weather permitting it will be out with the headlight and fusebox and the search for a broken wire etc. will begin in earnest.

 

We really don't deserve you on here! :-D

 

 

(The air filter has just been changed, Colin. Thanks for the thought though.)

[spospe]

euroserv - 2013-12-02 11:43 AM

 

The electrics on these vehicles are a bugger; but easy enough to repair when you know where to look!

 

Nick

 

Nick,

 

Just curious, but are the problems linked to water ingress? I can easily understand corroded wires in the presence of water and obviously this water has to come from somewhere. I wonder if it could be due to the oft reported water ingress. Is the problem more acute in older, less well sealed vans, or is it across the board?

[euroserv]

Hi Spospe,

 

The simple answer is no. The water ingress issue tends to have water running behind the windscreen scuttle and onto the engine or in the case of campers sometimes the water outlets at either end of the scuttle become over loaded with debris or the outlet pipes are not secure so excess water drains off where it is not supposed to but that is not what causes the wiring faults.

 

I have stripped many looms down while looking for faults and they are almost always caused by either moisture (that is a naturally occurring phenomenon under any vehicle bonnet) at a poorly sealed joint or cables that have become chaffed by rubbing together. Some of the worst ones I have seen have been covered with residue from muddy water, so I suspect that driving through deep standing water that does not kill the engine or gearbox gets it's revenge on the electrics down the line.

 

The national speciality of Italy is spaghetti and they sure know how to make a meal of it in an engine bay! The looms are not well made, the routing is not especially clever and the connectors are not well enough protected from the elements. The only positive thing that I can add to that is that at least the wiring is accessible. I have tried to solve electrical faults on Transits without success because it is hidden and illogical in the way that it is run in the engine bay. Many mechanics that I have spoken to have walked away from injection or glow plug wiring faults on Sprinters for similar reasons. The Fiat is not great but it is not the worst to work on.

Nick

[Steve928]

An update for anyone who's interested: getting closer but sadly no cigar as yet :'(

 

Firstly with the fusebox removed all the wiring and connectors are dry and clean and look as good as new with no outward signs of any corrosion at all.

Secondly, as Nick notes, the looms do seem to be of poor quality: cables bunched loosely together with scant protection other than their own insulation and free to rattle about in oversize cable clips. Multiplugs without cable grips so that any strain is taken by the individual terminals. Cables free to chafe on chassis members etc. It doesn't inspire confidence in the least.

 

The joint between ECU and injector looms tested OK but the fault seems to be within the loom itself about 6" below the fusebox at the point where the cables from the 3 multiplugs join to form one loom of about 30 wires. The engine management relays can be engaged/disengaged simply by twisting the loom at this point but finding the exact problem wire is proving difficult to say the least.

 

A possible reason why renewing the engine earth strap masked this problem for a while is that the relay coils have a permanent +12v but are switched by earth. To quote the manual: "This relay is energized by an (earth) control signal from pin G1 of connector B of the engine management control unit M010 and then forwards a power supply". So I plan to concentrate on the earth switching wires in the loom tomorrow..

 

 

[euroserv]

Hi Steve,

 

You will probably end up stripping most of the insulation from the looms in order to find the problem which I would expect to be nearer the nearside connector for the ECU. There are 2 or 3 joints that were made by the loom manufacturer and are not particularly good because the joined part is heat shrunk and this makes that part less flexible and the wires break at one end or both of the joints. Definitely start at that end and work back to the really fat part under the headlamp.

 

Before anyone starts Fiat bashing I should remind you that this is a Peugeot vehicle and Pug, Citroen and Fiat all signed off these designs! Seriously though; it's crap.

 

Nick

[Steve928]

Thanks Nick for the further useful pointers which I'll follow up on tomorrow.

 

What's keeping me going here is that this is definately a binary on/off stop/go break/make kind of problem: once the connection is made the engine runs just fine. Hopefully I'll get there in the end.

 

 

[spospe]

Nick

 

Not trying to hijack this thread, but you do keep on giving us tantalising insights to the wiring of X250's and I wonder if you have any suggestions as to fault prevention? For example would you recommend spraying WD40 over the connectors, tying the looms up more tightly with cable ties / using cable wrap to keep the wires together etc.?

[colin]

spospe - 2013-12-03 7:33 PM

 

Nick

 

Not trying to hijack this thread, but you do keep on giving us tantalising insights to the wiring of X250's and I wonder if you have any suggestions as to fault prevention? For example would you recommend spraying WD40 over the connectors, tying the looms up more tightly with cable ties / using cable wrap to keep the wires together etc.?

 

One thing that was posted some time back and confirmed by Nick, was the chaffing of loom as it goes to door, There are two body panels that the loom goes throu on the pillar, one is protected but 'inner' one isn't which causes problems, I've fitted a split grommet on mine.

[Steve928]

Found it! - presuming there's only one fault of course..

The earth control wire between ECU and fuesbox corroded through and burst out of its insulation deep in a clean and dry section of the loom.

Seems a very fragile wire for such an important function.

 

Very hard to pin down because the slightest movement of even an individual wire in the loom 30cm away would make and break the connection, sending me on many wild goose chases.

[euroserv]

Well done Steve,

 

Perseverance is key and you have it in spades. Welcome to the Fiat loom repair club.

 

Spospe;

 

I will get back to you about preventative measures, but in the meantime..... never spray WD40 on anything!

It's garbage and contains too much water to protect anything.

[spospe]

Well done to Steve indeed!

 

I am personally amazed that a wire can seemingly corrode in the middle of a run, unless the insulation was damaged enough to allow contact with either water, or another metal surface?

 

I have 32 years experience of telecommunications work and have never seen middle-of-a run corrosion of a wire without some other agency being involved.

 

So my question to Steve is, was there any sign of damage to the insulation from rubbing on any adjacent surface, or other wire, pipe etc.?

[Brian Kirby]

I don't think that damage can be the result of corrosion. Copper is generally highly resiststant to corrosion from water, hence its use for roofing, and water pipes. Corroded copper does not expand like rusty steel, and the corrosion is generally held to be protective.

 

That disruption to the insulation seems to me more likely to have been from mechanical damage, that had possibly also affected the copper strands within. That may have resulted in localised arcing and overheating, as the remaining strands carried the full current, possibly becoming brittle and eventually breaking as a consequence.

 

It is interesting that the other wires in the loom look undamaged, pointing to that individual wire having been defective before, or damaged during, the loom assembly.

 

However, a great bit of detective work and, on the face of it, relatively easily repaired into the bargain. Well done indeed, Steve!

[euroserv]

While Brian is right about the decorative qualities of copper when used for roofing, and the lovely bronze and green colours that ensue; but when it comes to wires, the green stuff turns to dust as the oxidisation is accelerated due to the current flowing and you are left with a white powder that won't conduct anything and breaks.

I dare say if a copper roof was used to transmit power or was used to earth anything; it would fare just about as well as the wiring! The plating industry relies on such reactions.

The insulation must have been compromised at some point by either testing probes or abrasion and the end result is but a matter of time.

 

I am looking for a broken wire on one of mine right now and it's going to be a long day.....

[spospe]

Brian Kirby - 2013-12-04 11:39 AM

 

I don't think that damage can be the result of corrosion. Copper is generally highly resiststant to corrosion from water, hence its use for roofing, and water pipes. Corroded copper does not expand like rusty steel, and the corrosion is generally held to be protective.

 

 

Copper on its own is resistant to corrosion, but as Nick says, pass a current through it, especially when it is in contact with other metals and things go bad, fast. I have helped out on numerous occasions with corroded caravan plug and socket wiring, where the wires (not the terminals which were of brass) had corroded badly at the point of connection. The effect was to turn the (un-tinned) copper into a crumbly mess which could not be soldered and which had to be cut out (the cable shortened).

 

I am handicapped by not having seen one of the infamous X250 earth straps in the flesh, but they seem in photographs to be made of untinned copper and my first reaction would have been to replace it with a tinned version and furthermore to solder the ends where they terminate into the crimped lugs (i.e. run solder into the lug to ensure that there was no possibility of micro-corrosion taking place out of sight).

[Steve928]

There was no sign of abrasion, spospe - nothing for it to rub on at this point, plus the wire wasn't even on the outside of the loom until I pulled it there (because I was tracing that particular wire as prime suspect).

 

Clearly water has found its way past the wire's insulation somehow whether it be damage during construction of the loom, porous insulation, manufacturing fault etc., but I'm confident the only added ingredient in use has been a bit of dampness. This was at a low point in the loom so would have stayed wet the longest I guess.

 

The conductor had turned to verdigris/dust at the very point of the break and was blackened about 10mm back in each direction. The photo probably makes the wire look more substantial than it is: it measures 1.3mm in diameter and the conductor comprises just 5 tiny strands of copper.

[T8LEY]

Steve928 - 2013-12-04 1:20 PM

 

There was no sign of abrasion, spospe - nothing for it to rub on at this point, plus the wire wasn't even on the outside of the loom until I pulled it there (because I was tracing that particular wire as prime suspect).

 

Clearly water has found its way past the wire's insulation somehow whether it be damage during construction of the loom, porous insulation, manufacturing fault etc., but I'm confident the only added ingredient in use has been a bit of dampness. This was at a low point in the loom so would have stayed wet the longest I guess.

 

The conductor had turned to verdigris/dust at the very point of the break and was blackened about 10mm back in each direction. The photo probably makes the wire look more substantial than it is: it measures 1.3mm in diameter and the conductor comprises just 5 tiny strands of copper.

 

Looks like you've been the victim of a poor manufacturing joint. Conductor winding machines are limited by the size of wire spool they use for the length of core they can produce. When a spool runs out of conductor the manufacturer has to make a joint to a new one. As for the insulation, that can go on forever, if the hoppers are constantly topped up.

 

I suspect the insulation damage was caused by the slow failure of the conductor joint ie heat. Once the insulation was broken moisture would be allowed in, causing oxidisation.

 

Excellent work finding the break.

[Brian Kirby]

Thanks for the extra information, chaps. I'll take a more guarded approach to copper wiring henceforth, having hitherto assumed it would be be "bomb-proof". Only 5 strands as well - no built-in redundancy there! Bet mine's the same, as well. :-(

[Guest Peter James]

Very Interesting Thread. Thanks to all who have contributed.

[BrianBW]

The earth strap relies on making contact with every strand on the strap to pass the starting current. When the strands get corroded the strands do not make contact to each other. This in turn stops the maximum current required for the starter motor. Even though if you do a resistive meter check it looks good.

[Steve928]

T8LEY - 2013-12-04 11:09 PM

Looks like you've been the victim of a poor manufacturing joint. Conductor winding machines are limited by the size of wire spool they use for the length of core they can produce. When a spool runs out of conductor the manufacturer has to make a joint to a new one.

 

How do they make the join?

Would each separate strand of the conductor run out at different times so that you would get, say, an overlap and an extra strand for a short distance?

 

Please don't say that all 5 strands would run out at once and they would then join the new spool of conductor with a granny knot. 8-)

[spospe]

Steve928 - 2013-12-06 10:01 AM

 

T8LEY - 2013-12-04 11:09 PM

Looks like you've been the victim of a poor manufacturing joint. Conductor winding machines are limited by the size of wire spool they use for the length of core they can produce. When a spool runs out of conductor the manufacturer has to make a joint to a new one.

 

How do they make the join?

Would each separate strand of the conductor run out at different times so that you would get, say, an overlap and an extra strand for a short distance?

 

Please don't say that all 5 strands would run out at once and they would then join the new spool of conductor with a granny knot. 8-)

 

Only one strand needs to be involved. If the joint of just one strand is high(ish) resistance, that can lead to a heat build-up which can lead to the insulation bubbling, which can lead to moisture ingress, which can lead to failure.

 

What I am 100% confident about, is that there is no way at all that a continuous copper wire in the middle of a run can corrode, without the intervention of some disturbing chemical, or (more likely) electrolytic action.

 

From Steve's description and photograph, I would go for the high resistance / heat build-up / insulation break-down / moisture ingress / wire joint, type of scenario. This will be quite a rare fault and possibly Steve will be the only person to suffer from it (I wait to be proved wrong!).

 

 

[Steve928]

Sadly it's time to revisit this thread almost one year on as the same symptoms have reared their ugly head one again on our old Elddis (which now lives next door).

 

About six weeks ago it cut out completely then restarted again after about 5 minutes and completed a 500 mile journey.

Then it had a trouble-free summer holiday covering 3500 miles.

Then last week at the first sign of a cold morning there it was again: imobiliser light on and no pumps running, then all normal about a minute later.

It's been slowly getting worse since then and today no luck at all: imobiliser light permanently on..

 

So today out with the headlight, cut open the spaghetti again looking for a wiring fault as it seemed to fit with resistance in a wire slowly getting greater.

 

This time I found a corroded section in the same earth control wire as before, but about 500mm away.

Again the conductor had turned to verdigris although this time the insulation was intact but a little lumpy and discoloured.

 

Pic 1 is the corroded wire.

Pic 2 is the location in the loom: right where the wire is clipped down into the inner wing and where the dirt and moisture tends to sit (beneath the ABS unit).

Replaced the entire run of that wire and so far all seems OK.

 

On my current van I'll be cutting that clip and raising that section of the loom up off the inner wing in the hope that it'll keep drier and cleaner..

[euroserv]

I am not surprised at all Steve.

While our 2007 vehicles were under warranty we had several go in for investigation of strange faults and were always told that a 'wiring repair' had been done. Since 2010 we have been doing our own repairs and have become pretty good at finding faults and fixing them but I have to say that these wiring issues are very common. At a guess I would say that all of the vans from 2007 to 2011 have had at least one repair. The later 2011 vans have been much better, but at the same time; the winters have been milder so maybe that has something to do with it!

 

The blue connector under the fuse box is known by the manufacturer as D004 but by our local dealer and ourselves it is referred to as 'rusty junction'. I had to repair one last week. We had a couple of injection faults coming up and it occasionally ran like a dog. I went straight to rusty junction and found corrosion in the plug joint between two cables; one of which just pulled straight out of the plug. A couple of new sections of wire were spliced in and the vehicle was fine.

 

When you drive in wet conditions, there is a constant mist of water circulating in the engine bay. Much of it evaporates from hot parts of the engine and under the bonnet lid but some of it lingers in out of the way places and exploits any and every weakness there is. There are many.

 

As for you Steve; your training has served you well and you too are becoming a master repairer. Well done.

 

N