13 replies to this topic

[Roky]

Hi all,

 

Recently when I went to start the car there was a load of white smoke coming from the starter wiring.

 

After investigation i found that one of the fusible links had burnt out:

 

 

It turns out that it is the wire that goes to the ignition switch which has also suffered some melting at the connector:

 

 

Now, I can fix the damage but what could have caused this? as I dont want to do the repair for it to just happen again.

 

Also, If I replace the fusible link like in this thread:

 

http://www.theminifo...ernator-wiring/

 

What rating should I use as 80 amp seems quite high. I have a 70 amp alternator though.

 

Cheers in advance for any opinions.

 

Pete

Edited by Roky, 27 June 2015 - 07:48 PM.

[KernowCooper]

Ok heres my take on whats happened, the fusible links are just there to protect the ecu against over charging from the alternator and a short to earth of the main battery feed into the ignition switch, usually there are 2 fusible links one goes to the main connection on the solenoid to charge the battery and the other brown goes into the ignition switch

 

The Light green/white is the auxiliary feed out which branches off with a Light green/orange, only after the ignition switch are these circuits fused as the Light green/white into the power distribution circuit feed has been damaged I'd be looking carefully at the loom to see where or whats caused the short to partly melt the wire onto the ignition switch and burn out the fusible link.

 

As the wire shorted on the feed into the fuse distribution circuit, I'd not expect to see any fuses blown in the fuse box.?

 

What model is yours Spi/Mpi

Edited by KernowCooper, 27 June 2015 - 09:23 PM.

[Roky]

Hi, thanks for the reply,

 

You're right about the fuses, none of them have blown.

 

The car is a '93 carb model but as I've discovered, cars of this era were wired/set up for SPI.

 

Forgot to mention there had been a corroded connection on the brown wire at the starter relay which I replaced right before this happened but I think this may be a red herring as nothing else was disturbed.

 

So, I shall check again the wiring from ignition switch and starter but hadn't found anything so far. Is it likely to be a short then?

 

Also, could it have been caused by a dodgy connection from the ignition switch or a dodgy starter relay?

 

Cheers

 

Pete

[KernowCooper]

There should not be a path to earth directly in the switch or starter solenoid to cause the melting of the wires, have a through check of any wiring visible, did you have the battery connected when you had the terminal off to replace it? no chance you flashed a live brown to earth ?

[Roky]

KernowCooper, thanks for the feed back.

 

Haven't had time over the weekend to check wiring due to family commitments so it'll probably be an evening thing this week.

 

When I did the relay terminal the battery was connected initially because I'd forgotten it was there (car is off the road and 99% of the time has no battery). I then remembered it was connected and so I disconnected it. I cant imagine that I flashed a live to earth as I hope I would have noticed it but also I thought given that the fusible link has melted I would have expected a prolonged short somewhere?

 

I've ordered a new connector for ignition switch and a new relay. Do you think a 70 amp fusible link is what's needed to replace the burnt out one.

 

One like this:

http://www.12voltpla...link-fuses.html

 

 

Cheers again

Pete

[KernowCooper]

You have a 70a alternator so taking into account production tolerances they may take 68a or 72a? so I wrote the original post and listed 80a, use the midi strip link fuse holders there safer than insulating the whole thing.

[Roky]

Yes I'll definately be using the holder to make things easier. They sell them on12voltplanet too.

 

I hadnt realised that link in my original post was actually your write up

 

Well I've been out tracing wires this evening and have found that the Green/White from the ignition switch has chafed through to the core where the loom passes through the lower dash rail there is a useless plastic gromet that had moved and the loom had obviously been rubbing against the metal. I shall tidy this up and order a few more parts.

 

I'll need some brown cable too but what do I need? I've seen 6.0mm² 50A and 8.5mm² 63A

 

Will either of these be ok?

 

Sorry for all the questions and thanks again for your help.

 

Pete

Edited by Roky, 30 June 2015 - 10:02 PM.

[KernowCooper]

I knew you were going to find it, well done that man, wheres the brown wire going ? to replace the burnt out wires near the alternator?

[Roky]

Yes, to replace the burnt out one.

 

Cheers

Edited by Roky, 01 July 2015 - 06:46 AM.

[KernowCooper]

80 amp for the alternator one.

[Roky]

Cheers, the 2 alternator ones are ok, it was the one from starter to switch that burnt out.

 

Pete

[Roky]

Anyone?

 

Just need to know the amp rating of the brown wire from starter to ignition switch.

 

Cheers

Pete

[KernowCooper]

The actual switch on the older cars was rated at  5 amps for Ignition, 16 amps for Starter and 15 amps for Auxiliary. The newer cars have some of this load taken off the starter circuit in the switch by using a  relay for the solenoid current, I would use 30amp for better volt drop

[Roky]

Cheers. I'll get some ordered.

 

Pete