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wiring diagram please. high beam indicator light constantly on

Posted: Wed 12 Jul, 2023 9:01 am
by stevend34
Hi All, I’m looking for a wiring diagram, specifically for headlights, for my 1990 SJ70 Sierra. Lots of diagrams online but can’t confirm what’s correct. Anyone got a link they could share?

reason…. Jumped in the car a few days ago to find battery flat. high beam indicator light on, even with no ignition or headlights on, taillights and various other things not working at all. Taillight fuse was blown and as soon as I put it back in blows again.
Disconnected various plugs and accessories and found that when I unplug the blue connector for the factory loom under passenger side of dash problem goes away. This loom comes from the fuse box and heads out into the engine bay. Also found with that loom plugged in, if I disconnect both headlights, problem also goes away. Current thinking is I have a short in the lighting wiring. Wanting to see which direction wires go from a diagram before I get cutting looms apart! Any tips appreciated

Re: wiring diagram please. high beam indicator light constantly on

Posted: Wed 12 Jul, 2023 3:20 pm
by christover1
Being negative switched headlights can cause confusions.
Power into lights is always on.
Suggests a short in power wire to headlight.
(maybe able to supply a separate power to headlights to see if it fixes it)
Poor earths in various places can cause issues, too. Power finds wrong paths.

Will search for wiring diagrams, I had them long ago.

Re: wiring diagram please. high beam indicator light constantly on

Posted: Wed 12 Jul, 2023 4:29 pm
by MartinG
Hi Steve. I had an issue with my hi beam indicator being on constantly, mine ended up being the break switch had come loose and was not working as it should

Re: wiring diagram please. high beam indicator light constantly on

Posted: Fri 04 Aug, 2023 9:02 am
by stevesierra
check or unplug the steering column stalk, I have actually rewired the headlight loom on a suzy , and installed dual relays , to handle the extra current for the head lights ,
headlight wiring is confusing due to the negative or ground being switched ! and always has a positive 12 volts on it

Re: wiring diagram please. high beam indicator light constantly on

Posted: Mon 07 Aug, 2023 9:45 am
by stevend34
Thanks all. Have got hold of a wiring diagram.
I did check and unplug things like brake switch and steering looms, as well as every other plug i could see :)
Were things got to, is after a lot of trouble shooting, the problem went away! That said, a dull headlight remained so I re-wired that to fix it. I suspect they are related.
always annoying when you don't know what it was for sure!