Driving well, put headlights on---- total loss of power

[thebigsham]

Been enjoying the brighter evenings. Took my 86 1.6 for a wee drive. No issues but when i decided to put my headlights on, the engine cut out and then refuses to restart or turn over. I have no electric running to the dash, iginiton or to the starter.
I checked the condition of the 7 fuses in the engine bay, i checked contacts on starter motor. I even ran jump leads from another battery directlty to the starter to try to by pass any other wiring issues. The starter didnt turn.

The engine hasnt seized as I was able to turn it by hand. Placing a spanner on the crank.
Is there any other fuses or relays or sneaky wiring hacks that I can try.

It has to be some sort of hateful wiring issue, any pointers are welcome.


As in over 7 years of ownership this is the first time it let me down.
Thanks.

[Paul G]

Check the earths - main engine earth by fuel pump, connections on battery, earth up to left strut top, earth from rear inlet manifold bolt to centre of heater plenum. Also obviously check the headlight earths in back of headlight boxes.

[thebigsham]

Will do that again. Now its brighter outside.

But do you know if there are any big fuses or relays which would take the power.

I cant find anything like it. But im surprised that simply putting headlights on can shut the entire car down.

[nigecapri]

Battery might have gone on all cells - unusual though.
Check battery lead connectors inside - if they're corroded then clipping leads on top will still not give enough current to crank it.
The small black wire to battery positive often causes grief - check for integrity.
Headlights are earthed inside the back of the headlight bowls with a screw point showing through under the wing - always go rusty and eventually cause problems.
Also some earth wires near offside bonnet hinge.
Rear light covers can give electrical problems if screwed up tight & cracked.

Let us know how you get on.

[thebigsham]

I may have found the problem. Or part of the problem. Under the steering colum theres a large black fuse holder. I pulled it open to see if the fuse was intact. It had blown i replaced it and then set about tracing the the power feed to work out if there was any cause for the fuse popping only to find it feed into a small brass relay with 5pins and an earth point. Relay is 81AB 15040AA.
Its time to run through the haynes manual to work out 1, what does it do. 2, how can I test it 3, how do i replace it.


Never a dull moment when youve been waiting for long bright dry days. And you end up with a complete power outage.

[Paul G]

When you replaced the fuse did you get any power anywhere?

I'm not convinced one fuse will cause a total power failure, you'd still be able to crank the starter with a jump lead applied directly to it. I'd still check the earths properly - take them apart and clean and re assemble them and also as Nigecapri said check you have connected the small second wire to the positive terminal and that it is in good condition and basically that the battery hasn't had a sudden internal fault which knackered it. It can happen.

Do the instrument lights come on with jump leads connected from another car?

[Taff50ish]

Hi there,

Just wondering. You don't have an original style alarm / immobiliser, which flashes the Headlights do you??? Some of the earlier alarms used to use the headlights and you could have a stuck relay, which fired back a current and took out the Alarm!!!???

As your problem is very strange indeed..... Best of luck with the hunt, cheers,

John....

[Mc Tool]

There are 2 wires that come from the batt + one big fat one goes to the starter motor assy and the other skinny one is the main feed to the electrical system from the battery , when the engine runs the alt feeds more power in from another point in the harness ..... so make sure the skinny wire is still connected or it will be as dead as a Dodo

[thebigsham]

I found two additional fuses below dash. One held a bullit fuse within a large black twistable fuse holder below the steering column this contained a white fuse that had popped also for anyone else out there who may be in search for fuses. Theres a fuse attached to the top of a black relay clipped onto a a panel below the dash in a row with 2 other relays. The first relay has a clear lid and inside thats a red fuse.

Thankfully ive only had to replace the one fuse. When refitting the under dash sections ive managed to relocate the black fuse holder to the area below the steering column so that if it ever blows again i can get it it without any tools and replace. As it rendered the car as a non runner when it last popped.

[Andrew 2.8i]

The first relay has a clear lid and inside thats a red fuse.

Hi,
That's for the heated rear window.
I'm glad you've found the problem, but what's actually causing the fuses to blow?

Andrew.