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Odd electrical problem with 750D headlights/tail lights

1129 Views 8 Replies 6 Participants Last post by  jimbauma
I'll start by saying the under-the-dash wiring in this 64 year old spider is a nightmare. There's been a LOT of cutting and pasting over the years.

Anyhow, the lights were working fine, and I may have momentarily grounded a wire, but no fuses blew. Now, the headlights won't go on unless I touch one of two left hand upper terminals on the fuse box (or the bar that connects them - see the pic). By "touch" I mean, with the ignition OFF, I simply use a small screwdriver and touch the terminal area. There's a small spark, the light to the right of the ignition switch goes ON, and the lights work! I'm not sure where to even begin!

I'd appreciate any advice!

Jim
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Interesting.
Check the grounds of your light wiring.
Do you have a wiring diagram?
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You probably need a color coded wiring harness to sort this out.
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If something happens when you touch the fuse box, you have to start there.

1 °) disconnect the battery and check :
- if all the wires of the fuse box are well insulated from each other and are well fixed to the box

2 °) check that the metal tabs of the box are not in contact or deformed. with your screwdriver you change the position of one or more tabs.

there is no other thing to check.

reconnect the battery and see if anything has changed.
let us know.
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Rick is correct that you need to get a wiring diagram ........ but that is not easy for a 6-fuse Spider. You might have to ask people with an matching year owner's manual. Note, Normale and Veloce diagrams are a bit different (electric fuel pump). Euro and USA slightly different ...... Euro with headlight dipping at steering wheel, USA a foot switch.

But basically the always hot side of fuse 1 feeds the "Terminal block" ....... look on the heater side of the steering column for a square Bakelite unit with multiple wires going to it. Verify all those wires are tightly connected to the Terminal block. One of those wires feeds the headlight switch. Unfortunately they are all red, so if needed you will have to just trace the physical wire.
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Here is Sprint one to at least get your investigation started

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If the left high beam worked with Number 1 fuse missing, there must be some other deviations from the wiring diagram.
Joe
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Here is Sprint one to at least get your investigation started
Thanks! This will help a lot...
If something happens when you touch the fuse box, you have to start there.

1 °) disconnect the battery and check :
- if all the wires of the fuse box are well insulated from each other and are well fixed to the box

2 °) check that the metal tabs of the box are not in contact or deformed. with your screwdriver you change the position of one or more tabs.

there is no other thing to check.

reconnect the battery and see if anything has changed.
let us know.
I'm thinking that scenario #2 makes the most sense... i have to put off that problem while i rebuild the rear brakes... always something to do!
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