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Discussion Starter · #1 ·
Greeting gents! So I'm chasing a short somewhere I think - I've been slammed with work and kids have kept me hopping so I haven't had much time to do any exploring. I'd really appreciate some advice and where to look first for any obvious problems. Here are the symptoms:

Front passenger turn signal doesn't work (and the dash indicator isn't working either on that one). It's dead whether I'm using the turn signal or emergency flashers. Bulb is good, flashers are good too.

Rear driver side brake light isn't working, it works when I engage the flashers or turn signal though.

Here's the history, I've recently replaced the the turn signal switch and the wiring harness that runs the length of the steering column. All was good until my daughter (4 yr old) was playing with the turn signal when I was loading the car up for school. I didn't realize it but it was partially engaged when I started the car. I righted it and it worked for a few minutes until they all died a few minutes later. I'm not convinced it's related, but the timing kinda sucks. Turns out the wires to the flasher units had worked loose, when I re-attached them everything work except for the front turn signal. I've been limping along as-is because things have been hectic. I have a tach mounted to the column and the backlight wasn't working - everything else was fine though. So when I was working on those other things I quickly redid the connection (which is poor and consists of twisting the wires together and wrapping in tape). I have it tied into the dash lights currently, I was going to put a beanie on it when it got it done but the light never came on. I called it quits for the night and buttoned it back up. But the tach is really erratic now.
  • Idle is set to 550 and it usually reads <100. sometimes it reads correctly at a stop light...
  • It "revs" up way to fast, jumps to 2100 when I'm at like...~1200. and then it stays there unless I'm close to 4k. again...sometimes it'll read correctly
  • If I turn on the dash lights the tach dies completely

Again...not convinced it has anything to do with the aforementioned items...but including it for background info. I'll tear into everything this weekend but I also need to replace a thermostat on the water heater and pulleys/belt on the dryer. So I'd love to have a list of obvious items to knock out first. Any help would be really appreciated!!

Thanks in advance!
 

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It sounds like you bought an aftermarket turn signal switch and they are known to be of poor quality. NOS Ford is the only way to go and they are expensive.


Maybe you shorted out the tach and messed it up.
 

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Discussion Starter · #3 · (Edited)
It sounds like you bought an aftermarket turn signal switch and they are known to be of poor quality. NOS Ford is the only way to go and they are expensive.


Maybe you shorted out the tach and messed it up.
That's kind of my thought on the tach thought, I was going to pull the power for the light and see what it does. I didn't think it could have shorted a problem elsewhere though...well I had hoped it couldn't.

And yes on the turn signal switch was aftermarket but it was a Scott Drakes. Any way to verify it's the turn signal switch? I should be able to pull the wheel and test some of the leads, right? I wouldn't have thought the switch would affect the brake light either...but at this point I'll try anything!
 

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The tach's signal wire connects to the - post on the coil so if the tach is messed up internally it is possible for it to mess with the ignition.


The brake lights and the turn signal use the same filament in the bulb. So the brake light wiring must go through the turn signal switch. That's what the turn signal switch does- with the lever in the middle position the brake light wires are connected in the switch. When you move the lever up or down the switch breaks the brake light continuity and connects the flasher into that circuit.
 

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Discussion Starter · #5 ·
Ah, didn't know that's how the switch works! Thanks a bunch - I'll dive in this weekend and check from voltages.

If anyone else sees anything then I'm still writing a list! ¯\_(ツ)_/¯
 
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