Technical multijet sometimes not starting. Low voltage at solenoid trigger.

[Paul Jaggard]

After 190k miles in 17 years, finally a serious problem.
A few weeks ago, catastrophic clutch failure...required a new gearbox too.
A severe thumping, using a solid towing-bar, resulting in the towing hook tearing off the metal mounting, and plastic bumper.
Usual garage too busy, so neighbour replaced clutch and box.
Everything seemed ok, (although there was a very small thumping sound just as the engine caught)
OK for a time, then after a long hot journey, wouldn't start.
The fault has recurred sometimes since. After waiting a few hours it starts again.

I've since added a secondary earth from battery to engine, and thought that this had solved my problem

Now, usually it starts fine, but sometimes it acts as if there is only a low voltage getting to the solenoid trigger.
I've noticed that the tank fuel pump doesn't turn off after a few seconds like it should.

I've had 1 blown 20a ignition switch, fuse a week or two ago. (maybe I left the ignition switch on too long when the engine wouldn't start?)
Today, I've discovered that if I put on the interior light, then turn the ignition switch to its second position, if it dims slightly then the engine will start.
However if it dims a lot (to around 6v) and the solenoid sounds feeble, then it won't start.
I've had the starter off, and it always works fine on the bench (though I have to push the interior solenoid button with something harder than my finger to give continuity at the main contacts.
My Haynes circuit diagram takes 2 wires from the second position of the switch. One via engine compartment fusebox, and "short circuit coupling" (whatever that is), to the ECU.
And the other via passenger fusebox to Body Control Unit.
The interior light seems to get its power from the body control unit.

Why would my ignition switch give this low voltage, and will I have to dismantle the steering wheel to get at it?
Or is the problem elsewhere? ECU? BCU? Relay?
I noticed that my neighbour was much rougher manhandling the ECU cables than I would dare be, but unplugging, and reinserting them didn't help.

After 17 years virtually trouble free, it has come as a bit of a shock to have these problems all at once!

Has anyone else experienced anything similar, or have any suggestions?

 

[Paul Jaggard]

The pump should come on for a few seconds then the ECU should detect the engine has not been started and switch it off again

Yes, that is why I worry that the problem might be with the ECU

Its hard to measure on a multimeter as it drops within a third of second

Yes I understand, I've tried starting a few times, and the lowest I got was 9.5v, but presumably it does drop below that.
At present, it is starting perfectly!

All that's left is to check it's belt and we can cross the altetnator off the list

What do I look for at the belt, I can understand that if it was not gripping well, then when one was drawing a large current from it,
it might start to slip?

I'll try swapping batteries when my wife gets home from work at 8.

While the engine earth might be good its probably worth making sure your neighbor has tightened up all the connections on the starter motor properly as a loose connection there can also cause similar problems to having a bad earth.

My neighbour said that he didn't take the starter off. Any faults are mine!
Actually, according to the circuit diagram, and indeed logic, there should be no current going to the starter motor, until the ignition switch is turned to the next position?, So even if I had made some mistake, it shouldn't affect the voltage reading when the ignition is turned to the previous position, should it?

I remember it being a real pain to sort out.

It's nice to know that I'm not the only one!

If a fuse blows once and not again then it can just be a one off, old fuse or some odd one off spike, but if its replaced and doesn't blow again then I would normally move on and ignore it. If it had blown multiple times either straight away or after a short period of time it might warrant further investigation.

It could easily be my amateur carelessness, but I can see the logic of not totally ignoring it.

 

[koalar]

A big voltage drop on the battery could still be an issue with the starter so that should be checked and is relatively easy to do.

The large voltage drop is at ignition on

Does this not rule out the starter or its wiring

How to test the starter wiring was given in post 10

But before crawling under the car I would swap the battery

 

[koalar]

Manual or dualogic?

 

[Paul Jaggard]

Manual
At the moment, I can't get it to fail to start

 

[Paul Jaggard]

When it last failed, the voltage at the fusebox, with the ignition turned on roughly halved.
But I can't remember now whether I charged the battery before it would start again.

 

[Paul Jaggard]

I think that your advice to swap batteries sounds wise.
I'll then try starting it a few times in the yard, then drive around the block (3miles) a few times, and try stopping/starting when I come past home.
I daren't change the battery today, in case it failed in the other car, when my wife was between stops!

 

[AndyRKett]

Are you sure?

Poor connection on the starter equals higher resistance, higher resitance equals less current. Less draw from the starter means there's more capacity for the rest of the system, Bulb should be brighter as it fails if the earth or power feed to the starter were the fault.

That's how I see it

A motor is effectively a dead short and one that is not spinning is just a big heating element. If there is a weak connection in a wire then this weak spot will also become a heating element. So if you have not enough power to turn the motor because the connection is weak, both the motor and the wiring to the motor can still draw and expel a lot of power as heat, without the motor ever spinning. Eventually you burn the motor out or the wiring or both, and the starter motor on most cars is not fused.

 

[Paul Jaggard]

I've swapped the batteries.
The diesel started more strongly with the new battery (just the same as when the battery has been recently charged), during the day, it has become slightly more sluggish, ...started maybe 10 times. (At a generous 5 secs per start, a good 50ah battery ought to be able to start it 50 times?)
The petrol started easily too.
I drove for 8 miles or so, and it still started ok.
On the petrol, there was virtually no dimming of the lights, on the diesel, it was the same as before.
I'll take it for the same run as I did a few days ago, when it was reluctant to start, after 8 miles.

Assuming it reacts the same, so that we can eliminate the battery as the problem, where do we look next?

BTW It is so kind of you all to give your valuable time and expertise on this. I really appreciate it.

Andy, whereabouts in Norfolk are you? I'm near Attleborough.

 

[koalar]

Asuming it reacts the same, so that we can eliminate the battery as the problem, where do we look next?

I take this to mean you need to do some more testing before eliminating or confirming the battery

If possible can you post a video of the rev counter and the lights underneath, as you turn the ignition on and as you crank the engine

I am perticularly interested in the behaviour of the oil, immo, rev counter, engine check and battery charge lights


What's the voltage drop with this battery at ignition on

 

[Paul Jaggard]

I'm not good with phones, but I'll try tomorrow.

 

[koalar]

I'm not good with phones, but I'll try tomorrow.

Don't worry about it

Just make a note of which lights come on as you turn the ignition on, which go out after a few second and whether any stay on when running

The rev counter should move while cranking and instantly show the revs as the engine fires up, if there is a delay the body computer isn't receiving enough voltage until the alternator kick in, such as here

Also if the voltage falls below 6V while cranking the clock will start flashing


It's important to set the time as its often the first clue there is something wrong

 

[AndyRKett]

Andy, whereabouts in Norfolk are you? I'm near Attleborough.

Really not all that far, I’m over towards diss, I’d offer to plug in and see if you have any error codes but I’m in the process of moving so all my kit is currently in storage and about to spend the weekend packing.

Something is clearly drawing a lot more power than normal and given the recent work you’ve had done you have to suspect it is somehow related.

 

[koalar]

OK have a decent meter, I think.

Battery charged overnight, tested at over 500cca on clarke tester , steady for 10secs.
recharged until charger said full.
Battery voltage now 12.78v
turn key to second position, and battery volts (at the battery terminals), drops to 11.55v
fuel pump keeps going.

Should have said Is this after the glow plugs have switched off?

turn key to start position, car starts almost immediately, the lowest voltage that I see is 9.9v

This will be much lower as the meter can not keep up, No point now it on a different battery, we should have unplugged the injectors and cranked it for a few second to measure

with no electric load, with engine at tickover, 14.2v
with full beam, and blower 14.09v

Great as expected

 

[koalar]

What do I look for at the belt, I can understand that if it was not gripping well, then when one was drawing a large current from it,
it might start to slip?

Cracking on the inside

Missing sections on the inside

Loose if your car is without aircon

 

[Paul Jaggard]

Video as requested. This is with other battery after 6 starts.
Notice the rattle, engine mounting?

 

[Paul Jaggard]

Something is clearly drawing a lot more power than normal and given the recent work you’ve had done you have to suspect it is somehow related.

Maybe, but bear in mind that when the clutch failed, and it was being towed home from the garage, it suffered such a severe beating, that the front was pulled off the car. That was my fault for not stopping the tower sooner. I don't like to blame my neighbours work...he was doing his best to be helpful, and knows far more than me.

 

[koalar]

Video as requested. This is with other battery after 6 starts.
Notice the rattle, engine mounting?

That's a great video and very informative

The lights are all behaving as they should

You can see the rev counter moving while cranking

Approximately just under 2 segments so around 170RPM which is normal

At 12 seconds you can see the voltage start to recover as the plugs time out and it is still climbing 11.77V so there is no voltage drop at ignition on

The meter takes around 5 seconds to stabilise and register the output from the alternator. To measure the cranking voltage with this meter we would have to disable starting and crank for around 5 seconds,

The clunk noise is it at 12 and 13 seconds as the starter solenoid energised and switched off

Oil light goes of quickly good pressure

 

[Paul Jaggard]

At ignition on, the voltage drop is from 12.5 to 11.6v
Is this normal? on the other petrol car, the light dims much less.
Anyhow, we are still in the situation where the engine is starting ok.
I guess I now have to wait until it doesn't....maybe with a different battery it will continue to be ok?!

I've not dared leave the ignition on for long, bearing in mind that the voltage drop presumably means that something is eating power, however, I noticed now, that the fuel pump only stays on for 16 seconds, not permanently, and not the normal 3 seconds.
But then my electronics have always been a bit odd, did you notice the mpg figure 97.1? It has been gradually getting more generous for years now.

 

[koalar]

At ignition on, the voltage drop is from 12.5 to 11.6v
Is this normal?

Yes while the glow pugs are heating

on the other petrol car, the light dims much less.
Anyhow, we are still in the situation where the engine is starting ok.

Great

I guess I now have to wait until it doesn't....maybe with a different battery it will continue to be ok?!

Fingers crossed

I've not dared leave the ignition on for long, bearing in mind that the voltage drop presumably means that something is eating power, however, I noticed now, that the fuel pump only stays on for 16 seconds, not permanently, and not the normal 3 seconds.
But then my electronics have always been a bit odd, did you notice the mpg figure 97.1? It has been gradually getting more generous for years now.

What's the voltage after the glow plugs have switched off

 

[Paul Jaggard]

The glow plugs are only on instantaneously, according to the fascia light They shouldn't be on at these ambient temperatures should they?

I've just had another theory. Did the severe juddering that the car suffered when being towed, damage the batteries internal cell connections, to give an intermittent fault?
The other panda was bought for a Ukrainian refugee staying with us. She got married yesterday, back in Ukraine, and will need the car to get to work next week, at least she doesn't travel more than a few miles from home, and if the battery fails on her, we have a quick solution.

It's hot & sunny here, I think I may drive 30miles to the seaside, and see what happens....