Hi all

I've got a very strange start problem on my 2006 TD6.

It started a few weeks ago. First cold day of the year and it sounded like a flat battery. Fired straight up with a jumper pack, so I replaced the battery.
With the new battery it fired up the first two times just fine.
However, that evening it wouldn't start again.
I assumed it was the starter motor so replaced that.
It was then fine for a few days, but now it's doing the same thing.

The ignition turns on fine, and everything works.
Turn the key to crank, and it's like the battery is flat. The starter motor just clicks a few times, then the dash turns off, and then the car resets.
Battery voltage drops as expected, so the starter is engaging and attempting to turn the engine.

However, if I put a jump pack on the posts it will start first time, every time.
If I remove the jump pack, turn it off and straight back on, it will not start. It's like the battery is flat, but it's not.
With the engine running the alternator is charging at about 14V.
Measured straight after turning it off, the battery voltage is 12.7V, and slowly dropping as expected.

I've measured the resistance from the battery to the two posts, and also measured resistance from the battery to the cylinder head. All the measurements are less than one ohm.

I'm stumped.

It had a new alternator last year due to charging issues, but that turned out to be a faulty ignition switch, so the ignition switch is also fairly new.

If anyone has any suggestions, please let me know.

Check your earth straps. John
2008 Stornoway Grey 3.6 Tdv8 Vogue - SOLD
2005 TD6 Java Black Vogue - Written off!!
GAP iiD BT-Sold

I forgot to say, I tried putting a jumper cable from the battery to the jumper post that it starts from with the jumper pack, and also from the battery to the cylinder head.
There is also no resistance from the battery to the engine blcok.

I'd ruled out the earth straps because of that, but I'll check them.

Any idea where they are?

IIRC behind the front offside wheel. John
2008 Stornoway Grey 3.6 Tdv8 Vogue - SOLD
2005 TD6 Java Black Vogue - Written off!!
GAP iiD BT-Sold

[quote="sparrowdclxvi"]Hi all

"The ignition turns on fine, and everything works.
Turn the key to crank, and it's like the battery is flat. The starter motor just clicks a few times, then the dash turns off, and then the car resets.
Battery voltage drops as expected, so the starter is engaging and attempting to turn the engine.

However, if I put a jump pack on the posts it will start first time, every time"

I'm taking a guess here but a clicking starter motor just means the solenoid is at least trying to pre engage the gear so that current then flows to the motor unit. If there is stiction then the battery on its own struggles to fully move the gear far enough to then make the connection from the battery to the motor. The jumper pack adds extra capacity to keep the volts (current) sufficient to overcome the stiction/drag and achieve full movement of the solenoid?

If it were my car I would look at the solenoid connections on the starter motor off and then even remove the motor to assess the solenoid contacts, movement and general connections Current: 2003 TD6 HSE
2004 Vogue SE 4.4
Previous: 1993 Classic 3.9

I would fit a new Earth strap between the body and engine, it's a very easy way to prove the earth strap rather than finding, cleaning and refitting the originols.

Faulty ignition switch?

Weegie wrote:

IIRC behind the front offside wheel.

[quote="steve k"]

sparrowdclxvi wrote:

Hi all

"The ignition turns on fine, and everything works.
Turn the key to crank, and it's like the battery is flat. The starter motor just clicks a few times, then the dash turns off, and then the car resets.
Battery voltage drops as expected, so the starter is engaging and attempting to turn the engine.

However, if I put a jump pack on the posts it will start first time, every time"

I'm taking a guess here but a clicking starter motor just means the solenoid is at least trying to pre engage the gear so that current then flows to the motor unit. If there is stiction then the battery on its own struggles to fully move the gear far enough to then make the connection from the battery to the motor. The jumper pack adds extra capacity to keep the volts (current) sufficient to overcome the stiction/drag and achieve full movement of the solenoid?

If it were my car I would look at the solenoid connections on the starter motor off and then even remove the motor to assess the solenoid contacts, movement and general connections

cass wrote:

I would fit a new Earth strap between the body and engine, it's a very easy way to prove the earth strap rather than finding, cleaning and refitting the originols.

nicedayforit wrote:

Faulty ignition switch?

I'm at a complete loss now.

The earth strap is fine, and this is backed up by no voltage warnings when running.

Without the second battery, the start motor just clicks.
With a second battery, it will try to turn over one or two compression cycles, then just die.
With the jumper pack, it will start like nothing is wrong.

It won't start with a second battery, but will start with the jumper pack.
This suggests it needs over 2000 CCA to turn over properly.
If that was definitely the case, then surely there would be sparks somewhere. That's a huge amount of current.

I'm currently leaning to a second faulty starter, but that doesn't really add up.

sparrowdclxvi wrote:

Weegie wrote:

IIRC behind the front offside wheel.

It is.
It's also perfectly fine.

[img]https://photos.app.goo.gl/6G3hQfRTtVfpsjCE9[/img]

[img]https://photos.app.goo.gl/wtcxe4H1eP4PVew87[/img]

When you have the not starting issue , if you can , measure the voltage not the resistance along the battery cables and connections, poor cables or connections will be highlighted with a voltage nearing 12 volt depending what the resistance is in the faulty area.
You may also have a poor cell in the battery even though its new.Just measure the voltage across the battery terminals when cranking.
Good luck.

Thanks for all the suggestions, I seem to have fixed it.

I think that the starter motor was failing, which killed the already dodgy battery.
I put a new battery in which worked for a few hours.
I then put a new starter motor in which worked for a few days.
I've been jumping it for the last week or so.

I then realised the replacement battery was actually smaller than the one that came out. It was the recommended battery, but I don't think it was the correct one.

I got another one that was the same size, put it in and she fired straight up last night. A couple of trips last night were all fine.
This morning she was fine as well.

So, as best as I can tell, the starter motor was failing (although I can't prove that as it's gone in exchange), which killed the old battery. The new battery was either faulty or just not up to the task, which led me down a rabbit hole.

Hopefully that's the end of this saga.