Technical Intermittent non-starting electrical fault

[ngowans]

I have an issue with my Ducato (2012 150 multijet) which my mechanic cant (or can't be bothered) to fix. In the middle of last year, I turned the key and nothing happened. The headlights symbol briefly flashed on the display then the display went black. I turned it back of off and gave it a second, then tried again and it fired up. Then it worked without issue for months.

Then at the start of December, my partner took it to work and got stranded on the M1, she was on the phone to AA idly turning the key 50-100 times and it fired up, it ran without issue and got her to the garage. They pissed about with it for a few weeks and gave us it back just before Christmas, they said they put a new earth strap on, and it seemed to start without issue. They said to bring it in if it does it again. We took it home and the very next day, same thing. So we took it back in and they tried replacing the ignition switch. This didn't solve the issue either. Then they booked their autoelectrician to come and have a look but couldn't get it to fail. After multiple attempts from the Autoelectrician to get it to fail over the course of a two weeks. I got fed up and decided to collect it. Sure enough it started first time, I drove it home then the next day I tried it, and it wouldn't start. Then after 50-100 attempts, turning on and off anything electrical and generally trying not to lose my rag I turned the key and everything lit up like nothing happened, I took it for a drive and it ran perfectly then drove it home. 2 hours later, I tried again. Nothing. I suspect the garage was giving me the run around and just can't be arsed to diagnose it.

I'm no electrician, but I've been on eLearn and got hold of all the wiring diagrams. I suspected it might be a sticky relay due to the intermittent nature of it, if it is I can easily fix it myself. But I can't see anything obvious jumping out at me, there don't seem to be any relays directly relating to the starter.

Does anyone have any ideas? I've spent about £3000 on it in the last 15k miles keeping it on the road (new glow plugs, new turbo, new MAP sensor, a new driveshaft, new clutch and I'm about fed up of it especially since it's only just at 73k miles and has been maintained like clockwork over the last 6 years.

Any help or advice would be most appreciated


Kind regards

A desperate desperate man.

 

[Communicator]

If I understand correctly the starter fails to turn the engine, and that not even a "clunk" from the solenoid is heard when attemting to start the engine.

Intermittent faults are often very hard to locate, so do not be too hard on your mechanic, or even the humble relay, as non of its kindred other than the starter solenoid are involved.

Your garage has replaced the engine earth strap, which has a reputation for causing problems on the x250 and later vehicles.

If the starter solenoid is not operating the fault is either in the solenoid/starter motor itself or in the ignition switch and the associated wiring.

The following was posted by @Anthony489 recently (01/01/23) in a similar thread.

"If you want to activate the solenoid without using the ignition key and relay, you could try the following:

Get a pair of booster cables, even the weedier type will do. Connect one cable to the battery positive, and the other to the smaller terminal on the solenoid. Colour doesn't matter ! Try and keep the two spare ends clear of the bodywork etc until you need them, maybe clip them onto the edge of a wooden chair or similar. Now touch the spare ends of the two cables together, whilst standing in a safe place, avoiding your hands touching the metal of the clips. This will apply 12 volts to the solenoid and be capable of supplying enough current to activate it."

You can connect to the battery via the jump start point.
The above will test the starter moto,r if applied when the starter motor fails to operate via the ignition switch.

Take care not to make any short circuits, leave ignition off and ensure that neutral gear is selected.

If starter motor OK then you are faced with the rest. Please do check and follow the procedure for disconnecting the battery negative.

With the negative disconnected check the battery earth connection, I have read of the battery positive clamp under the fuseboard being fractured. Is it tight on the terminal? are the four large fuses secure? Is the battery connection to chassis sound?

Connections to ignition switch could be loose, then there is the 2 pole donnector D004A, which should be checked for corrosion.

(For info the starter solenoid is initially operated by a high current winding which connects to chassis via the motor, which includes brushes which could be sticking. My wife once owned an Astra 1.7D on which we knew the battery was ageing, but it was the starter motor that failed first without any warning.)

 

[Crossingkeeper]

EDIT (My post has crossed with Communicator's but will leave it up because of the query regarding the electrical system)

I'm guessing that if the fault occurred when the garage had it they would have been able to trace the offending component (I'm reminded of a puzzling electrical issue that always occurred whilst I was driving until finally one day it happened on the driveway: and I was able to use my meter to trace an arcing connector!)

So it will be down to you to do the diagnostics next time it happens. Firstly are all the electrical systems dead as well as the starting circuit? i.e. you wrote:

The headlights symbol briefly flashed on the display then the display went black.

Does this still happen every time you get a no-start? do the lights still work etc? A complete electrical failure will be easier to diagnose than a failure of the starter motor to engage (though this will still be easier than if the starter motor turns and engine still doesn't start as some current threads are highlighting)

If the van electrics are live when the no-start occurs you could try purchasing a basic code reader to see if anything comes up; obviously a more sophisticated one is more likely to diagnose the problem but the expense will be prohibitive unless you can borrow one.

 

[ngowans]

If I understand correctly the starter fails to turn the engine, and that not even a "clunk" from the solenoid is heard when attemting to start the engine.

Intermittent faults are often very hard to locate, so do not be too hard on your mechanic, or even the humble relay, as non of its kindred other than the starter solenoid are involved.

Your garage has replaced the engine earth strap, which has a reputation for causing problems on the x250 and later vehicles.

If the starter solenoid is not operating the fault is either in the solenoid/starter motor itself or in the ignition switch and the associated wiring.

The following was posted by @Anthony489 recently (01/01/23) in a similar thread.

"If you want to activate the solenoid without using the ignition key and relay, you could try the following:

Get a pair of booster cables, even the weedier type will do. Connect one cable to the battery positive, and the other to the smaller terminal on the solenoid. Colour doesn't matter ! Try and keep the two spare ends clear of the bodywork etc until you need them, maybe clip them onto the edge of a wooden chair or similar. Now touch the spare ends of the two cables together, whilst standing in a safe place, avoiding your hands touching the metal of the clips. This will apply 12 volts to the solenoid and be capable of supplying enough current to activate it."

You can connect to the battery via the jump start point.
The above will test the starter moto,r if applied when the starter motor fails to operate via the ignition switch.

Take care not to make any short circuits, leave ignition off and ensure that neutral gear is selected.

If starter motor OK then you are faced with the rest. Please do check and follow the procedure for disconnecting the battery negative.

With the negative disconnected check the battery earth connection, I have read of the battery positive clamp under the fuseboard being fractured. Is it tight on the terminal? are the four large fuses secure? Is the battery connection to chassis sound?

Connections to ignition switch could be loose, then there is the 2 pole donnector D004A, which should be checked for corrosion.

(For info the starter solenoid is initially operated by a high current winding which connects to chassis via the motor, which includes brushes which could be sticking. My wife once owned an Astra 1.7D on which we knew the battery was ageing, but it was the starter motor that failed first without any warning.)

No there is no sound other than the keyswitch turning in my hand. It's like the battery isn't connected at all, no fuel pump sounds, no other solenoids or relays clicking anywhere. This might last 10 minutes or repeated attempts. Then suddenly it will start without issue. I will check the battery terminals again tomorrow when it's light, but now you mention it, I do remember an issue with the positive cable which runs over the exposed bodywork in the battery compartment having the insulation split and was shorting (it was actually more of a parasitic battery draw draining out the battery after a few days of the van being sat on my driveway rather than a sparks and mess type of short) at the start of last year, the cable has been patched with tape and the deceased battery was replaced. However I mentioned this to the mechanic and he checked it and said it shouldn't be an issue.

The battery earth connection is one of the ones which was replaced, in fact he left the old one on and it now has two earths. As mentioned he also added another to the engine which also has two earth straps.

The starter motor sounds ok when the power is actually getting to it. In fact the engine fires up and starts straight away (I had an issue with my fiat punto many many years ago where the starter motor pinion bushings had worn so badly that the starter motor would cease as soon as it engaged, then the car needed to be just shoved a half inch forward while in 1st gear to move the ring gear a touch and loosen up the starter. So I've dabbled in starter motors a bit in the past which is why I'm convinced it's purely electrical. At first I thought the ignition switch was shot, but now I'm thinking maybe the connectors since he said he replaced the ignition switch itself.

 

[ngowans]

EDIT (My post has crossed with Communicator's but will leave it up because of the query regarding the electrical system)

I'm guessing that if the fault occurred when the garage had it they would have been able to trace the offending component (I'm reminded of a puzzling electrical issue that always occurred whilst I was driving until finally one day it happened on the driveway: and I was able to use my meter to trace an arcing connector!)

So it will be down to you to do the diagnostics next time it happens. Firstly are all the electrical systems dead as well as the starting circuit? i.e. you wrote:


Does this still happen every time you get a no-start? do the lights still work etc? A complete electrical failure will be easier to diagnose than a failure of the starter motor to engage (though this will still be easier than if the starter motor turns and engine still doesn't start as some current threads are highlighting)

If the van electrics are live when the no-start occurs you could try purchasing a basic code reader to see if anything comes up; obviously a more sophisticated one is more likely to diagnose the problem but the expense will be prohibitive unless you can borrow one.

So the brief blink of the headlights has happened twice that I've seen myself. (my missus drives it more than me but she wouldn't notice if it burst into flames) it only happens the first time it fails to start. So for example I'll take it out, it drives fine, then I'll get in a few hours later, turn the key and the headlight symbol briefly blinks on and then off (like less than half a second) as though it really wants to fire up the electrics, then nothing, back to black dashboard, I do usually have the headlights on at all times so that might be worth noting. Then and subsequent turns of the key result in a black dash and no headlight symbol blink (this includes the odometer and clock which are also black. This stays black until I open one of the doors. Then the clock and odometer reappear exactly as it would when first getting in.

When it's in this "dead" state, there's no sound, not so much as the click of a relay or the buzz of a fuel pumps, nothing. There's also no lights, it's like the battery has been completely removed.

I'm hoping it's not the M001 Body computer but I've been going through the wiring diagrams but there's nothing immediately obvious..

As mentioned on my comment to Communicator, there was a fault about a year ago with the positive battery cable, I basically sent it to the garage to have the turbo done, and they left it hanging around so long that they disconnected the battery, when they reattached it they didn't route it through the little slot it lives in, and since it's under the footwell, the hatch got stood on quite a bit which split the positive cable and it was shorting on the bodywork (costing me a new battery in the process) I replaced that and fixed the positive cable and it went 6 months without a problem.

 

[Crossingkeeper]

Then and subsequent turns of the key result in a black dash and no headlight symbol blink (this includes the odometer and clock which are also black. This stays black until I open one of the doors. Then the clock and odometer reappear exactly as it would when first getting in.

This intrigued me so have just been out to look at my van....2009 build so dash display may be different but clock display is always on whether van is locked or not. When I open the door (without putting key in ignition) the display panel lights up and the mileage displays for a few seconds then reverts back to dark panel and clock display.

It therefore seems that when you have no clock display the fault condition has occurred.....easier said than finding it I know

 

[g8rpi]

When the fault is present this should be easy to locate. It could be a bad battery but is most likely a bad connection. Keep an eye out for the interior light everytime you open the door to get in. Does it come on before the fault appears? Does it work after the fault appears?
Does the van have centeral locking? sme as above, does it work when fault is present?
Trying to determine if it is total power loss including things that are on with ignition off or is it just ignition on items.

Robert.

 

[ngowans]

Apologies for disappearing but for the interests of future generations I have resolved the fault.

It turns out that the heavy duty cable coming out of the B099 battery fuse box wasn't tightened down, in fact the bolt supposedly holding it down was only on a couple of turns. That was why it would occasionally fire up and occasionally just not bother.

Suspected connector highlighted on wiring diagram below. Although it might have been connector A, the fiat eLearn page isn't super clear.

Now it's fixed it starts every time without fail.


How my mechanic missed this, (despite him actually adding a new earth strap inside the battery compartment) I will never know. I decided to have a go at fixing it myself and the first thing I checked was the battery wiring. I might have to give that particular mechanic a miss in the future.

Thanks for all the input, it was as always, most appreciated.

 

[Communicator]

I appreciate your reply but the loose connection that you marked on the diagram does not tick all the boxes. The cable indicated would be the largest diameter cable terminating at the CAL4 fuse on B099.
A failure to connect at this point at this point would result in the starter motor not turning, but not the complete dead state described in post #5 of this thread.
I therefore think that your alternative suggestion of a loose connection at B099/A is more credable, as that supplies the ignition switch. This could account for more of the symptoms mentioned, but I am wondering why the engine did not cut out while driving.

As the battery has been replaced, and there were other wiring problems in this area, may I suggest checking that the battery positive clamp (A001/A) is checked., but do observe necessary precautions when working in this area.

 

[ngowans]

I'm getting my wires crossed

I've been through all the connectors in the battery compartment and thoroughly checked them and it works perfectly now.

I couldn't begin to guess why the engine wouldn't cut out, but I presume power was coming to the ignition from elsewhere once the vehicle was running. Auto electrics is a bit of a mystery to be honest. To me the wiring diagrams just tell me what is connected to what, but not necessarily how it's connected or why.