Coil pack wiring

[mad in general]

Non starting car no spark between leads and coil pack and I have discovered via use of multimeter that I have 2 live wires to the coil pack connector.

Both 7.75V with ignition on and 6.1V when cranking.

I am led to believe that this is not right,

Can anyone confirm this and help with finding the fault

6 weeks now without starting!

Help please

 

[mad in general]

I'm going to be able to spend some time checking over things today, only a couple of hours will be available so if anyone can please help by giving some pointers it would be greatly appreciated!

 

[da rok]

as far as i know one should be a constant feed and the other a trigger, they are wired in pairs though, sounds like a short, have you done a diagnostics read on it?

 

[mad in general]

Tried various obd diagnostic, linking error to main ecu but reads airbags abs immobiliser etc...
Cannot connect to engine management

I believe it to be a short also, would I be right in saying it has to be on one of the signal wires as that shouldn't have any Voltage.

Any pointers for finding where the short is?

 

[mad in general]

Can I just run a wire from the coil pack straight to the ecu and see if it starts?

If so, which pin on ecu?

 

[mad in general]

Time spent before light ran out!

Performed basic continuity checks with battery and ecu removed
Injectors - ecu
4 - pin 89
3 - pin 60
2 - pin 90
1 - pin 59

Coil pack connector - ecu
Cable 1 earth
Cable 2 ecu pin 1
Cable 3 ecu pin 32

Without taking the loom apart I am unable to determine the fault.

Anyone able to assist please, I will have more time tomorrow with my multimeter so any pointers welcome.

 

[NorthloopCup]

Time spent before light ran out!

Performed basic continuity checks with battery and ecu removed
Injectors - ecu
4 - pin 89
3 - pin 60
2 - pin 90
1 - pin 59

Coil pack connector - ecu
Cable 1 earth
Cable 2 ecu pin 1
Cable 3 ecu pin 32

Without taking the loom apart I am unable to determine the fault.

Anyone able to assist please, I will have more time tomorrow with my multimeter so any pointers welcome.

It's earthed via the ecu when your ecu activates the coil pack mate.

Continuity checks aren't really worth a w**k tbf mate. You need to be checking the wiring for resistance as this will give you a indication that the wiring is OK or broken somewhere. Low resistance = wiring ok.
High resistance = corrosion or other issues.

From memory I'm pretty sure that with the ignition on you should have 12v at the thick white wire and that voltage is supplied via one of the relays on the n/s inner wing. Check for corrosion in there if you haven't already.

 

[mad in general]

It's earthed via the ecu when your ecu activates the coil pack mate.

Continuity checks aren't really worth a w**k tbf mate. You need to be checking the wiring for resistance as this will give you a indication that the wiring is OK or broken somewhere. Low resistance = wiring ok.
High resistance = corrosion or other issues.

From memory I'm pretty sure that with the ignition on you should have 12v at the thick white wire and that voltage is supplied via one of the relays on the n/s inner wing. Check for corrosion in there if you haven't already.

Thanks for the advice! I'll get into that tomorrow.

Am I right to be checking connector to ecu?
My knowledge of electrics is a bit pish to be honest, although I can follow instruction if pointed in the right direction.

Anything else I should be checking for?

 

[NorthloopCup]

Thanks for the advice! I'll get into that tomorrow.

Am I right to be checking connector to ecu?
My knowledge of electrics is a bit pish to be honest, although I can follow instruction if pointed in the right direction.

Anything else I should be checking for?

No problem!

The 2 smaller wires go direct to the ecu mate, so checking them for continuity only indicates a 100% break or not. Resistance indicates a broken wire that's got corrosion. You can also check for resistance to chassis earth if you have to get more involved, but I don't think you'll need to with this tbh.

Check resistance with the plugs disconnected as well mate as most (I've never seen one that doesn't!) ecu's only work on 5v signals so you whacking 9v down from your multimeter will f**k s**t up! Lol!

What you need to be seeing is 12v at the thick white wire in the coil pack plug when the plug is disconnected. If your not seeing 12v here, you need to investigate this first.

 

[mad in general]

No problem!

Check resistance with the plugs disconnected as well mate

What do you mean by this?


What you need to be seeing is 12v at the thick white wire in the coil pack plug when the plug is disconnected. If your not seeing 12v here, you need to investigate this first.

I will try again tomorrow but I think I already measured the thick white at 7.7v with ignition on. 6.1v while cranking.
The wire right next to this also measures the same!

 

[NorthloopCup]

You need to have the coil pack plug and the ecu plug disconnected mate.

 

[mad in general]

You need to have the coil pack plug and the ecu plug disconnected mate.

Again thanks!

I will have a dig about tomorrow then, I will update when I get some results.

Cheers!

 

[bloke]

Tried various obd diagnostic, linking error to main ecu but reads airbags abs immobiliser etc...
Cannot connect to engine management

does the engine management light come on when you turn ignition on?

 

[mad in general]

I will double check tomorrow but I don't believe it does.

What would prevent the engine management being accessed via obd port?

 

[mad in general]

does the engine management light come on when you turn ignition on?

 

[bloke]

sounds like ecu isn't getting power?

 

[mad in general]

Ok, I'll have to investigate that then, any pointers?

 

[mad in general]

does the engine management light come on when you turn ignition on?

If it's the engine block shaped light bottom right of the dash then no it does not come on with ignition on.

It does light up when you do the dash diagnostic function

 

[mad in general]

You need to have the coil pack plug and the ecu plug disconnected mate.

No power to the thick white cable with ignition on.

7.5v to the other 2 cables though!

 

[mad in general]

Pin

30 Before ignition 12.4v
66 after ignition 0.4v
3 power earth 10.7v
28 power earth 10.7v
33 power earth 10.7v

About to start checking for resistance

Will post results, any information on what I need to do or check is greatly needed!

 

[NorthloopCup]

No power to the thick white cable with ignition on.

7.5v to the other 2 cables though!

Is that with the ecu disconnected as well?

 

[mad in general]

Is that with the ecu disconnected as well?

Correct, no power with ecu disconnected.

Thick white coil pack wire is showing continuity and no resistance to 3 identical colour and thickness wires in fuse box

All relays tested with 9v battery and clicking!

 

[NorthloopCup]

Correct, no power with ecu disconnected.

Thick white coil pack wire is showing continuity and no resistance to 3 identical colour and thickness wires in fuse box

All relays tested with 9v battery and clicking!

It doesn't make sense that your getting 7.5v at the other wires!

 

[mad in general]

It doesn't make sense that your getting 7.5v at the other wires!

I'm currently stripping back the loom from the coil pack to the fuse box to inspect these three wires, I can't help but think I have a break somewhere

 

[NorthloopCup]

I'm currently stripping back the loom from the coil pack to the fuse box to inspect these three wires, I can't help but think I have a break somewhere

Yeah that's the only thing it can be tbh mate.

 

[bloke]

Yup, you're missing a live or most probably an earth somewhere.

 

[NorthloopCup]

Yup, you're missing a live or most probably an earth somewhere.

Yeah and more than likely the Earth at the gearbox is the culprit as that's the main one for the ecu.

 

[mad in general]

Yeah and more than likely the Earth at the gearbox is the culprit as that's the main one for the ecu.

Is this the strap from box to chassis in the passenger wheel arch, If so that seems good.

 

[NorthloopCup]

Is this the strap from box to chassis in the passenger wheel arch, If so that seems good.

No mate it's at the back of the gearbox nearer to the bellhousing.

 

[mad in general]

So yeah, up and running!

The earth to the bell housing looked ok but I removed the ring connector and cut back the wire to get fresh copper. Hooked it all back up and bingo!

Thanks for all the help guys

 

[NorthloopCup]

So yeah, up and running!

The earth to the bell housing looked ok but I removed the ring connector and cut back the wire to get fresh copper. Hooked it all back up and bingo!

Thanks for all the help guys

Winner winner chicken dinner!!

 

[mad in general]

Winner winner chicken dinner!!

That's been approx 250 miles since and not another fault has surfaced! Well apart from me forgetting to reconnect the reverse switch!

Earths! Nightmare.

Cheers for the help

 

[NorthloopCup]

That's been approx 250 miles since and not another fault has surfaced! Well apart from me forgetting to reconnect the reverse switch!

Earths! Nightmare.

Cheers for the help

No problem mate.

 

[mad in general]

Bump!

New issue but I believe relates to the wiring.
Code p0351.
Firing on 2 cylinders, cant remember which pair but theres definitely no spark from the coil pack to leads. 2 coils packs tested. Same issue.

Checked the wiring back to ECU with multimeter for resistance. All checks out fine.

Any bright ideas? Car has sat for 1 month now.

 

[mad in general]

@NorthloopCup

 

[mad in general]

Just to provide my solution.

Pin 32 on the ecu plug was a loose connection to the ecu. Crushed it, some contact spray and it's been fine since.