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Discussion Starter #1
I went to take my 85 GT out for the first time tonight and noticed that when I pull the knob to turn on the dash lights the car drops in idle about 400 rpms and wants to die. There is also a bunch of flickering (of all the lights) going on. I'm guessing there is a short some where, I've checked the cables going from the battery to my ground and battery to solenoid everything is good, where else should I check? Thanks
 

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check to make sure the alternator is charging. Simply start the car and disconnect the negative cable from the battery. If the car continues running the alternator is good if not the car will shut off pretty much instantly.

After that check and alternator is good. Mustangs in those years had problems with headlight switches burning up right at the dash. Check that out to make sure okay.
 

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you i would say check to make sure the alt can keep up with the electrical demands. is your car stock? underdrive pullies? you may need a higher amp alt.
 

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Discussion Starter #5
The car is all stock. I disconnected the neg. side of the batt. once the car was running and everything was fine, so the alternator should be ok. Now if the headlight switch was bad would the car still drop in idle, like it's doing? The dome lights, dash lights and head lights are all flickering simultaneously.
 

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The car is all stock. I disconnected the neg. side of the batt. once the car was running and everything was fine, so the alternator should be ok. Now if the headlight switch was bad would the car still drop in idle, like it's doing? The dome lights, dash lights and head lights are all flickering simultaneously.
Head light switch (may) cause those symptoms. My buddie bought an 85' brand new and had to replace the switch 3 times in the 4 years of him owning it. Yes, check to see if you have a good ground on the cable not being coroded and the ground strap connected.

When the idle dropped, thats just the load/amps being put on the electrical system itself.

Another thing you could do is check all your fuses to see if okay, then start pulling one at a time to see if the surging stops when you pull them out (with the car running)
 

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Discussion Starter #7
Now that you mention the switch having been replaced on your buddies car, It reminds me that I have replaced it one time before. I'll check the fuse thing you were talking about and if I have no luck with that i'll replace the switch and go from there. Thanks again for the help.
 

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Discussion Starter #8
Alright so I changed the headlight switch and for the most part the flickering of the lights is gone. I took it out yesterday though and the flickering came back for a quick sec and then went away. I guess I just need to dig a little deeper and see what I find. Thank you all for your help.
 
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