Technical wiring mystery

[junkycarjunky]

Hi. My car came to me with all lights disconnected. I have it all sorted except for one issue. When the headlights are on, the left front and rear turn signals work but very weakly, as if the headlights are robbing current from the turn signals. I cannot find a schematic for a 1971 850 Spider. Can anyone help? Mike.

 

[FR85]

Mike, I had a similar problem and it was down to a poor earth on the repeater, I actually ran a wire from the rear of the mounting screw forward to one of the retaining screws on the rear of the headlight to get a better earth rather then sand away chassis paint behind the wing.

 

[bugsymike]

No garuntee, but it does sound like an earthing issue.
Unless the wires to the headlights are not in their correct position, but poor earthing is likely.

 

[chris3234]

Remove and clean any earth cables you can find


Also worth replacing the main earth or any cables if it looks a bit corroded

 

[junkycarjunky]

Hi. My car came to me with all lights disconnected. I have it all sorted except for one issue. When the headlights are on, the left front and rear turn signals work but very weakly, as if the headlights are robbing current from the turn signals. I cannot find a schematic for a 1971 850 Spider. Can anyone help? Mike.

Can I assume that the “repeater” is your name for the “flasher”? And thank you for the schematic! Yup

 

[FR85]

Can I assume that the “repeater” is your name for the “flasher”? And thank you for the schematic! Yup

That's it, one and the same. Depending on your model it may or may not have a hazard switch fitted, I think there is a slightly different repeater and an additional red wire that may or may not be on the diagram that could throw you.

 

[bugsymike]

A quick way to prove or disprove any query regarding the earthing is to run a good connection temporarily from the earth side of the battery directly to the metal part of the bulb holder on one of the offending lights. Another thing would be to use a DC volt reading on a cheap multimeter, to check that you are actually getting 12 volts to those lamps . A lot can be lost along the way with old wiring.

 

[junkycarjunky]

That's it, one and the same. Depending on your model it may or may not have a hazard switch fitted, I think there is a slightly different repeater and an additional red wire that may or may not be on the diagram that could throw you.

Thanks for your reply and help. I will delve into it Monday and let you know what I find. Mike