Technical Ducato powers up but won’t crank

[Fedupoffiats]

Help needed.

I went out to my 2007 3.0 Ducato just before Christmas as I’d got a recovery to do and the dash lights came on but it did absolutely nothing when I turned the key.

I tested the battery. 12.9 volts.

I checked earth straps. We’re a little dirty but nothing major. Cleaned them up and put them back….. Nothing.

Bought a new battery and fitted it…. Nothing.

Bought a new starter motor and fitted it…. Nothing.

Tested continuity of earth straps just to be sure and they were fine but I’ve added another earth strap to the battery terminal just because.

I added an earth strap directly from the negative terminal on the starter motor to the body of the truck and when I turned the key, I did get a click from the starter at that point. It blew the fuse in the little fuse box thingy in the battery compartment so I’ve changed that and took the earth strap I added off the starter.


I don’t get it!! I have done thousands of miles in this truck and it was working fine the day before.

I have tested that there is a decent connection on the starter terminals from the battery and the brown/black wire from the key switch to the starter motor is live when the key turns so I assume the switch is ok.

Immobiliser light some on and goes off and as far as I can see/hear all the relays click/work when I turn the key.

I’ve put it in gear and rocked it back and forth in case the starter was stuck.

I feel like I’ve tried everything but is there something I’m missing?

My head is fried now…….. I need to get some help!

 

[GettinBetter]

..... but will only be measuring meter lead resistance.....

..Exactly ..and, at the voltage and current the DMM is putting through said lead.

If the earth strap is getting warm, it is a sign that it is failing. Replace.

Agreed, and a bigger one if poss'.

 

[Fedupoffiats]

You may have and I’ve missed it but have you tried running a temporary earth from the starter to a different earth so for instance a jump lead from starter earth to battery earth? Clutching at straws now tbh!

Yeah I put an earth from starter to the frame and that’s how I got the starter to click but wouldn’t turn over still.

 

[Fedupoffiats]

I am not aware of earth terminals on starter motors. Typically they are earthed via the fixing bolts.
It seems possible that in the confusion, you have mistakenly earthed the motor terminal on the contactor. This would explain blowing the fuse at the battery positive. (Possibly a 150A mega fuse.)



If the earth strap is getting warm, it is a sign that it is failing. Replace. (One former fleet operator (Euroserve) has suggested replacing every four years.

The resistance of the earth strap cannot be measured with a DMM. You can check for continuity, but will only be measuring meter lead resistance.

I agree. I also have read of internal corrosion in these earth straps. See attached photo of failing strap.

Again I agree.

I am not familiar with the jump points on the x250, but is it possible to attach a jump lead between battery negative, and an engine lifting lug?

I can only conclude by suggesting again, that the earth strap is changed.

I have experienced a starter motor fail abruptly, that is without warning. OK starting from cold at home, but not working for return journey after about 20 miles. Suspected battery as that was old, but presumably it was the starter brushes that had expired.

Thank you for this. Very informative.

The starter motor has 3 terminals.

Live

Switch

Negative (which has an earth to the body of itself)


I believe the fuse popped when I added the extra earth to the starter (was definitely earth and not live or switch) which makes me wonder is I have a short somewhere?

I will replace the earth from the gearbox to the frame and see if that helps.
It looks fairly new like it has been replaced not too long ago and I’ve cleaned it up with sandpaper and wire brushed the nuts and bolts with WD40 (making sure to dry them before replacing to avoid build up of dirt shortly after)

 

[jackwhoo]

Had a saga on here with a seized alternator causing a Non. Start

I recall the thread it took a lot of commitment to find that alternator had seized solid whilst parked up

Seized alternator stopped started starter turning

Owner could turn crank with spanner but only in opposite direction to normal due to alternator free wheel.

 

[Communicator]

Thank you for this. Very informative.

The starter motor has 3 terminals.

Live

Switch

Negative (which has an earth to the body of itself)


I believe the fuse popped when I added the extra earth to the starter (was definitely earth and not live or switch) which makes me wonder is I have a short somewhere?

I will replace the earth from the gearbox to the frame and see if that helps.
It looks fairly new like it has been replaced not too long ago and I’ve cleaned it up with sandpaper and wire brushed the nuts and bolts with WD40 (making sure to dry them before replacing to avoid build up of dirt shortly after)

For clarity of description I have attached a photo of a typical starter motor. It has three terminals.

The upper large terminal is the live battery connection.

The smaller terminal offset to the right is the solenoid connection, from the ignition switch.

The lower terminal has the flexible connection to the motor attached. It is NOT an earth terminal.

I would not bother to wipe the surfaces after cleaning. A better precaution would be to add a thin smear of vaseline. This will help to prevent moisture creeping into the cracks, and causing corrosion.

 

[Fedupoffiats]

For clarity of description I have attached a photo of a typical starter motor. It has three terminals.

The upper large terminal is the live battery connection.

The smaller terminal offset to the right is the solenoid connection, from the ignition switch.

The lower terminal has the flexible connection to the motor attached. It is NOT an earth terminal.

I would not bother to wipe the surfaces after cleaning. A better precaution would be to add a thin smear of vaseline. This will help to prevent moisture creeping into the cracks, and causing corrosion.

What is the purpose of the lower terminal with the flexible wire attached to the body of the starter?

 

[Communicator]

What is the purpose of the lower terminal with the flexible wire attached to the body of the starter?

To connect the solenoid nornally open contact to the starter motor internals.

 

[jackwhoo]

The solenoid is a big electrically operated switch capable of handling the hundreds of amps current required to turn the starter motor(it does something else but I'm not explaining that here)
When the solenoid is activated by battery +ve on the thin wire from ignition switch it connects the big fat +ve wire from the battery to the lower flexible wire .
The flexible wire is not connected to the starter body it is the live wire to the actual motor inside the starter motor assembly.

 

[Communicator]

I said this in post #20,
"I am not aware of earth terminals on starter motors. Typically they are earthed via the fixing bolts.
It seems possible that in the confusion, you have mistakenly earthed the motor terminal on the contactor. This would explain blowing the fuse at the battery positive. (Possibly a 150A mega fuse.)"

I am now suggesting that it is more probable that it was the larger CAL4 fuse that blew, or is a higher rated CAL5 fitted on the 3 litre?

 

[Fedupoffiats]

I said this in post #20,
"I am not aware of earth terminals on starter motors. Typically they are earthed via the fixing bolts.
It seems possible that in the confusion, you have mistakenly earthed the motor terminal on the contactor. This would explain blowing the fuse at the battery positive. (Possibly a 150A mega fuse.)"

I am now suggesting that it is more probable that it was the larger CAL4 fuse that blew, or is a higher rated CAL5 fitted on the 3 litre?

To connect the solenoid nornally open contact to the starter motor internals.

Ahh I see. So I’ve gone and earthed that and blew it which makes sense now as the fuse popped at exactly that point.

Do you reckon I’ve fried the starter solenoid at the same time?

Luckily, the original starter is still working haha

 

[Fedupoffiats]

The solenoid is a big electrically operated switch capable of handling the hundreds of amps current required to turn the starter motor(it does something else but I'm not explaining that here)
When the solenoid is activated by battery +ve on the thin wire from ignition switch it connects the big fat +ve wire from the battery to the lower flexible wire .
The flexible wire is not connected to the starter body it is the live wire to the actual motor inside the starter motor assembly.

Thank you for that. It makes more sense now.

I assumed that was an earth strap from the solenoid

 

[Communicator]

Ahh I see. So I’ve gone and earthed that and blew it which makes sense now as the fuse popped at exactly that point.

Do you reckon I’ve fried the starter solenoid at the same time?

Luckily, the original starter is still working haha

Hard to tell. As battery is new possible maximum current would flow, but this would be interrupted by the fuse, not the solenoid contacts. Motor itself should be OK, as effectively shorted, and not in main current path.

 

[Fedupoffiats]

Hard to tell. As battery is new possible maximum current would flow, but this would be interrupted by the fuse, not the solenoid contacts. Motor itself should be OK, as effectively shorted, and not in main current path.

Yeah it blew the 80amp big fuse on the positive battery terminal.

I’ve changed it now so that fuse is operational again.

I’m going to change the earth straps for new ones and let you know how I get on.

 

[Communicator]

Yeah it blew the 80amp big fuse on the positive battery terminal.

I’ve changed it now so that fuse is operational again.

I’m going to change the earth straps for new ones and let you know how I get on.

I am sorry but as it was not the CAL4 fuse (slow blow) which carries the main starter motor current, the only alternative would be the 150A mega fuse, as originally suggested. This fuse supplies the engine bay fusebox, which in turn supplies the ignition switch via a 30A maxi blade fuse.

See attached diagrams. The circuited diagram is unfortunately cropped. It was originally posted by another member of this forum.

 

[Anthony489]

Hi

To supplement the advice above, here's a marked up diagram of the X250 starter motor and charging circuits.

The main starter current (say 500 Amps) flows from Battery Positive via the Cal4 high current Fuse next to the battery, then via the Jump-Start junction in the engine compartment (under the plastic flip-up cover marked +) to the main terminal of the starter motor. The return current goes via the engine block and gearbox casing through the earth strap (C002 to C003) to the chassis/body. Finally the current goes from another part of the chassis/body near the battery and via a short thick cable to the Battery Negative.

The solenoid current (say 50 amps very briefly during pull-in then dropping to 10 Amps) flows from Battery Positive via Fuse 70 (150 Amps) and Fuse 3 (30 Amps) to the ignition switch H001. Fuse 3 is in the underbonnet fuse box. From there (in the start position) it flows via Junction D004 to the solenoid terminal of the starter. Return current has the same path as the main current above.

Probably worth noting that if there is an internal problem with the starter motor that prevents it from properly engaging, the solenoid current will remain at 50 amps for much longer than it should, which will overheat/damage the solenoid if Fuse 3 doesn't blow.

At risk of repeating previous comments, the resistance of starter cables and connections is measured in thousandths of an ohm, so an ordinary multimeter is of no use for distinguishing between a good connection and a not quite good enough connection. Voltage measurements are useful, but must be done whilst the circuit is drawing current to yield much useful information. A second pair of hands is useful for this. Try to keep the negative lead of the voltmeter always connected to the same point (e.g. battery negative) or you will lose track of what you are measuring. As an example, if you operate the starter and read any more of a fraction of a volt with the meter between battery negative and engine block, that indicates earth strap trouble.

 

[Fedupoffiats]

Just an update on this -

Swapped out the 80 amp fuse that had blown (fitted by previous owner) for 150 amp (the correct size that it should be that was pointed out)

I have removed the earth strap from the gearbox to the frame and replaced with a high throughput strap and it’s up and running.


The earth strap that I removed looks relatively new. Very slight corrosion on the connectors but I’d cleaned all that up.

Just goes to show that even though they look good/clean you never really know how bad they are inside of them crimped on connectors.

Thank you all for your help

 

[Communicator]

@Fedupoffiats ,

Thanks for taking the time to tell the forum. It is satisfying to know that you have succeded.

 

[Fedupoffiats]

Update to the previous update -

I drove 200 yards down the road and realised that I could only drive up to about 30 miles per hour and the truck wouldn’t rev beyond 3k.

Plugged it in and it had a million fault codes…. Turned it off and it wouldn’t start AGAIN!!!


I’ve added 3 more earth points from various areas of the engine to the frame. I went a bit overboard but it has worked and now cranks better than ever!

 

[GettinBetter]

.....I’ve added 3 more earth points from various areas of the engine to the frame....

This means the the engine earth path is compromised (gaskets, sealant, corrosion), the chassis earth path is compromised (paintwork, corrosion) and both to varying degrees.
You may find in time your lights may play up (going dim, lighting other lights, or even not fuctioning) as the earth paths deteriorate, in fact just about anything electric. But at least you'll know now.

Great that you cracked it, AND reported it here.