X250 Engine earth fault

[Ninian]

Hi, What resistance would you expect to see on the meter between the engine block and the earth terminal used for jump starting the vehicle. Any ideas.

[Alanb]

Allan of Aandacaravans said:-

 

"We worked on Tom Clayton's Fiat (2005 pre X250) this morning which came to us with a habitation battery Alternator charging issue.

There had been a history of charging from Alternator problems since purchase many years ago. Even resulting in a trip to Schaudt in Germany to try and resolve it. In 2011 they had a bigger Alternator fitted with 110amp output.

 

We quickly got the Alternator charging at 12amps but the Alternator voltage at the Habitation battery was a poor 13.7v. Starter battery was 13.9v.

This would provide almost 'adequate' Alternator charging, just slower than ideal, so I continued investigation.

 

If I put the negative of the of the volt meter directly on the engine block it recorded a very strong 14.51v from the Alternator, but at the chassis or on the Starter battery negative it was the lower 13.9v recorded above. Clearly something restricting the charge from the Engine block to the battery, mostly likely Poor earth straps."

 

 

This is interesting because my Fiat Ducato based PVC is a late X244 model built in 2006. The last time that I looked, I traced the insulated starter battery negative cable to an engine block earth point at the starting motor. The connection at this point appeared to be a flag type of lug, applied to the cable at a gap in the insulation. The same cable appeared to continue to the main chassis earth point.

 

Allan was measuring a higher voltage beween the starter battery positive and the engine, than between the battery terminals. If the same earthing method as on mine, was used on Tom Clayton's vehicle, the readings suggest that the battery negative connection at the starting motor was suspect. However if that were the case, I would expect that the performance of the starting motor would be affected.

 

I am curious as to the metal, and connection method, of the flag lug at the starter motor. I would guess at a crimped plated steel lug, but a non ferrous lug is possible. Perhaps I may be able to check with a small magnet.

 

Alan

[aandncaravan]

Ninian, it is hard to find a perfectly untarnished point on an old Engine block, even on metal that looks 'clean'. So it is not always easy to identify if any resistance shown the meter is a true reading or down to tarnishing on the metal contact point.

 

I prefer to create a big current load (fridge running on 12v is a good start point), monitor the voltage then continually 'scratch' the metal with the probe for a few seconds and note the highest readings.

 

 

Alanb, yes the negative ran from the Starter battery terminal downwards to a chassis point just below the battery where the cable was stripped of insulation and a tang crimped over the bare cable and bolted into the chassis. This point is usually sound on this vehicle as it is 'out of the Water'.

The cable then continued on to the Starter Motor and bolted directly to the top of the Solenoid.

The Red Live + Battery feed to the solenoid approaches the end of the Solenoid.

It is at the solenoid that the connection seemed to be an issue. The whole area looked clean so I suspected internal corrosion inside the Crimped connector.

On Tom's van it looked like the usual Galv Steel.

 

The simplest solution sometimes appears to be to remove the Earth at this point, but I strongly suggest you do not. The Solenoid attachment to the Starter isn't strong. Attempting to undo the cable requires significant force, sometimes results in a damaged solenoid and a bill for a new Starter.

 

There was no sluggishness of the Starter to operate, and only one of all the vehicles we have ever dealt with had a 'slow' Starter.

I don't know why it doesn't have a bigger impact on Starting, I can only guess that while voltage drop must be significant, a modern battery is still able to deliver, despite double the work load?

 

 

 

[witzend]

Had a problem while in Portugal drove into pothole and battery light came on and stayed on for several days although alternator kept charging eng battery so I decided to leave well alone and sort upon return home on journey light became intermittent and for last 200 mls stayed off so difficult to find fault reading this thread I've checked all earth points and haven't found any faults so just wondering if anyone has had similar fault

[Alanb]

Allan,

 

Many thanks for the warning re disconnecting the negative lead.

 

I had just had a quick look, and some finger tracing on the vehicle, before I read your post. I realised that my memory was in error, and as you correctly state, that working from the battery negative, the flag terminal to chassis comes first, and then the cable continues to the starting motor.

 

The connection at the starting motor is via a ring terminal with a second nut on the lower starter fixing bolt. Both this ring terminal and the terminal at the battery seem to be non magnetic, hence non ferrous. I will need to get further under the vehicle to check the flag terminal. Perhaps tomorrow when I hope to look at some other parts as well.

 

Alan

[Alanb]

Hi Witzend,

 

You do not say what your base vehicle is. So I must assume that it is an X250, with which I am not familiar.

 

Here are some generalpoints to consider.

 

I would not reccommend driving for any time with a battery warning light showing.

 

How do you know that your alternator continued to charge the vehicle battery?

 

Is it possible that you were on EHU overnight, and that your mains charger also charges the vehicle battery?

 

Do you have a solar panel that could be charging the vehicle battery?

 

Have you checked the starting battery voltage with the engine running?

 

Perhaps others can help you more than I.

 

 

 

[witzend]

Alanb - 2017-03-11 10:46 PM

 

Hi Witzend,

 

You do not say what your base vehicle is. So I must assume that it is an X250, with which I am not familiar. Yes X250

 

Here are some generalpoints to consider.

 

I would not reccommend driving for any time with a battery warning light showing..1 Only drove around Portugal for a couple of months and back from Portugal around 1500 mls

 

How do you know that your alternator continued to charge the vehicle battery? 2 Checked with volt meter

 

Is it possible that you were on EHU overnight, and that your mains charger also charges the vehicle battery? 3 No never use hook up

 

Do you have a solar panel that could be charging the vehicle battery? 4 No only Hab batterys

 

Have you checked the starting battery voltage with the engine running? 5 Yes 14.4 v

 

Perhaps others can help you more than I.

 

Thanks have answered your Questions in Qoute

 

Some time ago I had the D- wire break in the loom which I repaired and fault was fixed. Today I though I'd check my repair just in case and it was Ok. So to be sure I decided to replace this wire from alternator to control box on stripping wire out of loom I found that it had worn almost thru on the ECU mounting bar I'm hoping that this was the fault as wire was worn badly and thinking about it the fault corrected it self when weather was damp during last 200 miles so maybe helping the connection

[Alanb]

Hi Witzend,

 

If the damaged D+ wire was making a resistive fault to chassis at the point of contact, it is possible that sufficient current would flow to illuminate the warning light, but not sufficient to pull down the alternator field circuit. It could result in the alternator being slow to build up output. (Lazy alternator syndrome?) It is also conceivable that the alternator could still function with the D+ wire broken. It depends on how much residual magnetism exists in the alternator rotor.

 

I think that there is a very high possibility that you have found the source of your problem.

 

Alan

[Robbo]

Allan (AandN), good advice to check the live side of the alternator/charging system.

 

The live side goes from the alternator > starter motor > contact board (+’ve lug for emergency starting) > starter battery.

 

Testing revealed the following:

Voltage at alternator = 14.37 (no load) / 14.20 (load)

Voltage at starter motor = 14.25 (no load) / 13.90 (load)

Voltage at contact board = 14.00 (no load) / 13.60 (load)

[Load during test 23 amps. Earth to engine block]

PS. The contact board was removed prior to the test and all contact points thoroughly cleaned and the unit replaced.

 

I suspect a bad connection at the starter motor as this is forward of the engine and more likely to suffer corrosion. However, I’m loathe to mess around with this connection because of previous comments (ie. potential damage to solenoid).

 

Consequently, I’m thinking of running a supplementary heavy duty cable from the alternator (+ terminal) to the contact board. Any comments.

 

 

 

 

 

 

[aandncaravan]

Robbo, that is interesting, I did not know the live path from the Alternator had such a convoluted path to the Battery, I had always assumed it went straight to the live battery terminal. Never bothered to trace it on an X250 as never been an issue, but clearly likely to be in the future.

 

That is a crazy path to route such a lot of potential current (160amps!!!) when there are so many connections, but probably does so to save cabling by using the existing + battery cable which runs to the Starter?

 

Not so big a deal on a Commercial van, but like the Alternator Earth (or lack of) issue it's a major problem for a Motorhome, especially one with a big habitation battery bank.

 

 

I would suggest that if you are putting your new cable on the Alternator B+ I would run straight to the Battery Fuse terminal to the same fuse that supplies the Starter battery.

 

 

 

 

 

 

[Robbo]

I tried to attach a couple of pdf files to my previous post but the file size was too large.

 

The files are FIAT DUCATO X250 Alternator wiring.pdf and FIAT X250 Starter, Alternator.pdf

 

The files can be found in a thread http://www.fiatforum.com/ducato/294963-fiat-ducato-2007-not-charging.html

 

These files may of interest to other Fiat X250 owners with similar problems to mine or those wishing to know more about how the system works (for future reference).

[aandncaravan]

The Fiat wiring diagram Isn't great when shrunk to fit!!

Probably better to use the link above?

 

 

[Robbo]

aandncaravan - 2017-03-13 9:32 PM

 

I would suggest that if you are putting your new cable on the Alternator B+ I would run straight to the Battery Fuse terminal to the same fuse that supplies the Starter battery.

 

 

Good idea Allan, cut out the middle man and avoid all the convoluted wiring. I'll search for the access hole through the bulkhead (OR get a contortionist with long arms to help me) :-D

 

PS. The pdf files in the link may be a bit out of date. For instance, I have a CAL5 fuse on the positive side of the starter battery whereas they show a CAL4 fuse. Maybe the MH converter opted for a higher output alternator and therefore inserted a higher fuse rating.

[Alanb]

I have been following this thread and have started to think that there may be another effect of a faulty engine block earth, as well as charging and starting problems.

 

The engine is supported by rubber mountings, as I believe is the exhaust pipe.

 

So what does that leave for an alternative current path? Gearbox bearings, driveshafts, CV joints, wheel bearings and suspension.

 

Bearings and CV joints will not take kindly to a current flowing through them, as they could suffer from spark erosion.

 

It does of course depend upon where lights, heated rear windows ( I don,t have the latter.) etc are earthed

 

My lightly used 2006, X244 PVC has under 27,000 miles on the clock, and while I am not suffering from any charging or starting problems, I did have a noisy front wheel bearing changed several years ago.

 

There are posts on the Fiat Forum relating to an X244 Ducato that had charging problems, and also mentioned a faulty wheel bearing.

 

Have I missed something, or do I have cause for concern?

 

Alan

 

 

[Microblackcat]

Microblackcat - 2016-12-23 5:17 PM

 

Hi Nick,

I know this is an old chestnut, but your name keeps coming up and I think you might be able to advise me.

 

Fiat Ducato 2.3 - 2013

I have a wireless OBD2 device and the app tells me the code is P0124 - "Throttle/Pedal Position Sensor/Switch "A" Circuit Intermittent", and I clear the error code before each start up.

 

The engine warning light continues to come on despite me adding an additional braided strap as suggested in a number of postings over the years.

 

I'm convinced this IS the issue as there are no other symptoms suggesting poor running, lack of power or reduced revs etc.

 

The new earth strap runs from the -ve earth stud by the bonnet to a convenient stud on the engine (i'm fairly confident it's connected directly to the engine as my meter shows zero ohms resistance when touching the engine stud with other parts of the engine).

However, when I measure the resistance from the -ve earth stud to the engine, I can't get it to zero ohms .. it consistently reads 0.1 - 0.2 ohms. Is this enough resistance to make a difference, that would fool the sensor to think it's voltage is too low ?

Curiously, due to another issue, I flattened the battery recently and had to jump start from my wife Golf. Guess what .. NO warning light illuminated !!!

Once back on it's own starter battery, the dreaded warning light now reappears.

Can you shed any light on these symptoms please ? Is it just a case of finding a better earth ?

 

Thanks in anticipation.

 

Brian Knight

 

So .. some months on and building up a bit of familiarity with what's what under the X250 2.3 bonnet.

 

My P0124's have disappeared and replaced themselves with P2454 & P2002, now suggesting DPF, but having thrashed it for 20 miles maintaining 3000+ rpm, no DPF regeneration was prompted, followed by 230 miles up the motorway and back this weekend with same errors.

 

So, I plucked up courage to try and change the chassis/gearbox earth strap, first removing the air filter top & filter itself (but not the body .. looked a bit trixy) and after removing the dead mouse and orange filter crumbs, I managed to remove the earth strap (with difficulty). I had to pop off a cable/pipe connector near the gearbox end to access the hex screw.

 

Thought I'd share a few photos for those attempting this as it might seem obvious for those in the know but a bit daunting for me ..

Shots show air filter removed and both end connections .. one on gearbox (8mm hex screw) and the other on a chassis stud (8mm nyloc nut).

I replaced the existing braided cable with 50mm2 pvc sheathed cable about 210mm long eye-to-eye.

The existing cable actually has one 8mm crimped lug & and one lock-washer (gearbox end) with a 10mm crimped lug, but actually 8mm on both ends of the replacement cable would be better. I guess they use a 'standard' cable that's also used elsewhere. I used soldered lugs.

 

I cleared the OBD error codes and it started up without further error, but I'm not confident it has solved the issue. I'll let you know how it goes !

 

Edit: Can't post the photos .. 100k limit .. what's the best way to share these ?

[Microblackcat]

Here's a link to the photos ..

 

https://www.facebook.com/media/set/?set=a.1867292473536728.1073741832.100007679799747&type=1&l=cde9792ad8

[aandncaravan]

Just as likely that your Dead mouse and filter crumbs may have been as much of an issue as the Earth strap? Several posts on here in the past of all sorts of Warning Light/running problems as the result of Rodents in the Air intake which I assume yours must have been if there were Filter crumbs as well?

 

 

On the X250 the Battery Terminal to Earth strap bolts on to the chassis just to the rear of the battery itself under the Drivers feet.

Check that this chassis contact is perfect, it is as important as the Gearbox to chassis strap under the Air Filter housing. Because it is generally 'dry' it tends to be less of an issue, but should still be checked.

 

Ideally an additional strap should run from under this Battery box eyelet then onto the Engine block but I tried fitting one last week and it's almost impossible without the Vehicle on ramps.

I now see why Robbo struggled.

 

 

 

 

 

 

[colin]

aandncaravan - 2017-03-19 7:09 PM

 

Just as likely that your Dead mouse and filter crumbs may have been as much of an issue as the Earth strap? Several posts on here in the past of all sorts of Warning Light/running problems as the result of Rodents in the Air intake which I assume yours must have been if there were Filter crumbs as well?

 

 

As this, I had a long running problem due to mice in the inlet tract, finally solved with the help of Nick.

In my case one of the mice had got past the filter and was dead in the U bend, At times the mouse would be sucked up and hit the air mass sensor, in my case causing a drop in power and various engine fault codes, It seems Fiat haven't got a code for 'mouse in inlet tract' which meant our local Fiat (un)Professional hadn't a clue.

[aandncaravan]

Microblackcat, If you did find a Mouse in the Inlet tract along with Filter debris, then I would suggest you look to removing and cleaning out the entire inlet tract up to and including the Air Mass meter?

If the Air filter has broken up with bits sucked towards the engine, there may be 'contaminants' in/around the Air mass meter (and possibly Mr Mouse's brother?)

 

I can't remember which Air filter manufacturer it is but I think the Mann Air Filter has an Aluminium mesh that prevents rodent access to the engine. The Fiat one just has an open plastic framework.

 

 

 

 

 

[spospe]

aandncaravan - 2017-03-19 7:09 PM

 

Check that this chassis contact is perfect, it is as important as the Gearbox to chassis strap under the Air Filter housing. Because it is generally 'dry' it tends to be less of an issue, but should still be checked.

 

 

I used to work in telecommunications, designing, installing and maintaining telephone exchanges. The exchanges ran on 50 volts dc and Section fuses were commonly rated at 125 and 250 amps. The power distribution was done with copper bus-bars which were joined together at intersections and equipment racks by means of lapped joints. The method of ensuring a good low resistance joint was to coat the bus-bars with petroleum jelly and then file them lightly through the jelly. The jelly and filings were not removed afterwards and the two bus-bars were then bolted together. All these joints were in 'dry' locations and the system worked perfectly for the life of an exchange (20+ years). This method could be used for earth straps and would ensure the lowest possible resistance for the connection points as well as offering some protection from damp in less than 'dry' locations.

[Microblackcat]

colin - 2017-03-19 7:53 PM

 

aandncaravan - 2017-03-19 7:09 PM

 

Just as likely that your Dead mouse and filter crumbs may have been as much of an issue as the Earth strap? Several posts on here in the past of all sorts of Warning Light/running problems as the result of Rodents in the Air intake which I assume yours must have been if there were Filter crumbs as well?

 

 

As this, I had a long running problem due to mice in the inlet tract, finally solved with the help of Nick.

In my case one of the mice had got past the filter and was dead in the U bend, At times the mouse would be sucked up and hit the air mass sensor, in my case causing a drop in power and various engine fault codes, It seems Fiat haven't got a code for 'mouse in inlet tract' which meant our local Fiat (un)Professional hadn't a clue.

 

Sorry .. my mistake. I thought they ALL came with a Dead Mouse ?

Is it possible to fit a wire mesh behind the bonnet air intake slots, without detriment to airflow ? Or get a 'CAT' fitted ?

[colin]

Microblackcat - 2017-03-19 10:29 PM

 

 

Is it possible to fit a wire mesh behind the bonnet air intake slots, without detriment to airflow ?

 

Yes, I have fitted a SRBF spacer with wire mesh between opening and inlet pipe, the size of opening in spacer and type of mesh ensures the free airflow remains the same as the maximum the original opening is capable of, Probably OTT for a 2.3 engine, but I was not taking any chances of problems.

[Microblackcat]

colin - 2017-03-19 10:40 PM

 

Microblackcat - 2017-03-19 10:29 PM

 

 

Is it possible to fit a wire mesh behind the bonnet air intake slots, without detriment to airflow ?

 

Yes, I have fitted a SRBF spacer with wire mesh between opening and inlet pipe, the size of opening in spacer and type of mesh ensures the free airflow remains the same as the maximum the original opening is capable of, Probably OTT for a 2.3 engine, but I was not taking any chances of problems.

 

Sounds interesting !

Can you give a bit more detail ? Why SRBF ?, & what size mesh did you use (I assume it's stainless steel or zinc ?)

[Microblackcat]

aandncaravan - 2017-03-19 8:50 PM

 

Microblackcat, If you did find a Mouse in the Inlet tract along with Filter debris, then I would suggest you look to removing and cleaning out the entire inlet tract up to and including the Air Mass meter?

If the Air filter has broken up with bits sucked towards the engine, there may be 'contaminants' in/around the Air mass meter (and possibly Mr Mouse's brother?)

 

I can't remember which Air filter manufacturer it is but I think the Mann Air Filter has an Aluminium mesh that prevents rodent access to the engine. The Fiat one just has an open plastic framework.

 

 

 

Thanks for the suggestion .. that all seems a bit daunting for me at this stage. Would I do any damage if I put my endoscope camera down the pipe (carefully) ?

[colin]

Microblackcat - 2017-03-19 10:51 PM

 

colin - 2017-03-19 10:40 PM

 

Microblackcat - 2017-03-19 10:29 PM

 

 

Is it possible to fit a wire mesh behind the bonnet air intake slots, without detriment to airflow ?

 

Yes, I have fitted a SRBF spacer with wire mesh between opening and inlet pipe, the size of opening in spacer and type of mesh ensures the free airflow remains the same as the maximum the original opening is capable of, Probably OTT for a 2.3 engine, but I was not taking any chances of problems.

 

Sounds interesting !

Can you give a bit more detail ? Why SRBF ?, & what size mesh did you use (I assume it's stainless steel or zinc ?)

 

SRBF because I had a lot kicking around, no4 mesh which is 4 wires per inch, in stainless.

Two layers of SRBF with the stainless sandwiched between, stuck together with a Silkaflex type adhesive, can't recall the thickness of SRBF offhand, at a guess was 8mm cross member side 2mm inlet side.