Lights don't work after 21 years of sleep

[93/42260]

Hi,

 

I am in the final throws of putting a Spitfire Mk4 back on the road after 21 years of it being stored. The body, running gear etc is all done but now I have come to the electrics:

 

I have a running engine with oil and ignition light and the wipers work but everything else seems dead. there is no power at the fuse box when I put an avometer  on each of the + and - terminals on the three fuses but the fuses themselves seem OK.

 

Is there something I am overlooking or do I need to go round every terminal and check it is sound and that all the earths work?

 

Thank you

 

Chris

[Colin Lindsay]

Eliminate each one in turn; it’s the only way you can trace the break or short. If you at least have oil and ignition lights there’s power somewhere, but it seems there’s a break somewhere along the system. Try moving or bending the loom that you can reach under or behind the dash; it may be that you can reconnect the circuits and this will point to where the problem lies. Make sure that nothing is getting dangerously hot, especially things like the choke cable if the engine is earthing through this due to nowhere else to go. 

[93/42260]

Thank you.  Looks like a long weekend ahead tracking this down.

[rlubikey]

Assuming the Mk4 is similar to the 1500, one fuse should have permanent 12V, one has 12V via the ignition switch and the third has 12V via light switch (sidelights). The fuse with permanent 12V has a siamesed contact at the live end!!! One side of the fuse cap is live, the other side of the cap goes off to the light switch. So, if you remove the fuse, you disconnect the feed to the switch.

 

All the contacts can be poor due decades of grot, often not helped by previous owners using an abrasive to clean them and taking the plating off in the process which makes the contacts prone to corosion. But the other problem is the siamesed contacts - each is held in the plastic base, which relaxes over time until the contacts are no longer pressing firmly together on the fuse cap. Poor contacts create heat and the plastic relaxes more.

 

When you go down the fuses checking for 12V, make sure you check the contacts not the fuse caps and check the contacts on each side of the fuse cap to locate the permanent 12V and lights feed.

 

Hope this helps, Richard