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No brake lights

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Scotamx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Scotamx Quote  Post ReplyReply Direct Link To This Post Topic: No brake lights
    Posted: Sep/19/2018 at 2:35am
Hello everyone,

I wonder if someone could help?

I am putting together a '69 AMX (the car was in bits) and have been checking the wiring.

I fitted a new turn signal switch and it meters out okay for continuity in each position.

Connected up a battery and turned on ignition. Both rear turn signals flash okay, right and left. Rear lights flash, dash indicator flashes also.

I have the brake switch removed from the pedal. Activate switch, no brake lights. I know the switch is closed when the plunger is out and open when it is in so with plunger out, no brake lights. The switch meters out correctly so it seems fine.

If I check the volts at the red/white trace feed from the fuse box to the brake switch I get 12v when the switch is disconnected (open circuit), or the plunger is in. If the plunger is out (in other words when you would push the pedal) I get no volts at the red/white connector at the switch or at the fuse box. So, when the circuit is completed I get no feed through to the turn signal and hence out to the bulbs.

However, if I connect a feed directly to the green wire at the brake switch connector, through the turn signal, I get both brake lights coming on. So, I assume that the circuit for the brakes is good through the turn signal switch.

For some reason, as soon as the brake switch activates, it kills the 12v feed from the fuse box.

I have the hazard flasher disconnected so that is removed from the circuitry just in case it was that.

Also, the brake/turn fuse was blown in the car when I got it which may point at a problem somewhere.

I have thought this through and through but can't work out what is going on so any help appreciated.

All the best
Sandy
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1970390amx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1970390amx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/19/2018 at 1:34pm
My guess is that you high resistance in the circuit somewhere. using a dvom to check things will not point this out, it does not draw enough power it show this. The fuse holder has two terminals, when you lose power does it drop power at both terminals? This might indicate a lose connection at the fuse or a bad fuse. Could be a loose connection of wires to the terminal also. I think power to the fuse comes from the ignition switch, could be corroded terminals inside the switch.
1970 390 4speed Bittersweet shadow mask AMX
1970 Amx missing most everything, or in a box
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Scotamx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Scotamx Quote  Post ReplyReply Direct Link To This Post Posted: Sep/19/2018 at 3:27pm
Thanks very much for replying.

I found the problem when I took the fuse panel out.

A broken track.

Fixed with a bit of a bodge but all works as it should now (see picture).

Just a quick query with the instrument panel in place, and then the dash binnacle, I get quite a bit of white light bleeding out onto the speedo and the tach from, especially, the parking brake light.

Is this normal?

I think it could be helped if there was some sort of gasket at the end of the white plastic tubes for both the upper and lower (parking brake) warning lights.

Apologies if this seems a stupid question, but no other AMX's, or Javelins, or even AMC's in Scotland.

All the best
Sandy

Edit:- drat, no means of attaching a photo, but basically I made up a wire link to replace the failed one inside the panel.
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304-dude View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Sep/19/2018 at 3:49pm
If you like to give a try... use imgbb.com. no need to create an account. Just try the upload, and then the option in create codes to, full bbcode, it defaults to hyper link. Copy and paste into your reply. You can test by preview before posting.

Also, be careful about the panel, from what I understand there are some ground strap, and fitment issues. Maybe someone can chime in about working with such dash and instrument cluster.

Glad you spotted and found a way to fix the issue.
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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