Blinkers and running lights not working

Blueinfan

Active Member
Mar 18, 2021
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Car: 1991 Ford Mustang LX Convertible - 89,000 miles

Hi All,

I have an issue were the left and right turn signals and running lights do not work in the front. No blinkers in the rear work. Running lights do work.

The hazards do work. In pic1 I have replaced the items that have a red X

The fuse with the light has also been replaced.

All new bulbs have been installed with new headlight hardness purchased from LMR.
 

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bird_dog0347

still married haven't seen testicles in years
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I had a similiar issue a few years ago, there was a wire that was loose behind the hazard switch, I think it was orange... check there first.
 
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Blueinfan

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Mar 18, 2021
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Yes, it plugs into the back of the switch, I don't recall what it's for and don't have my car here with me to go look.
sure enough that Orange wire was out!!!

Thank you

However, running lights in the front are not working. The headlight harness is new.

Hazards, turn signals in the front and rear are working, rear running lights are working.
 
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manicmechanic007

Mustang Master
Sep 26, 2017
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Damn straight a factory man is going to plug a known good switch into your harness straight away
And if the wires have issues you will find that straight away as well
Pull out or melt is what those wires do best
After they get loose they start to melt (high resistance makes big heat)
I told you the story where the engineers were bragging about having 6 miles of wire in the new then new Fords? (mid 90's)
We told them "well you need eight" We cant even get the headlight switch out"
And of course the TS switch wires are not long enough to use the tilt without them pulling themselves out of the harness
Ford is not alone on this problem
K car Chryslers were actually worse and would shut off driving down the road if you used the tilt
 
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Blueinfan

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Mar 18, 2021
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Headlights work right?
Yes, headlights do work
front and rear Hazards work when activated, I could hear the clicking going on the flasher on the fuse box
front and rear turn signals work when activated, I could hear the clicking going on the flasher under the radio
license plate lights work

I have replaced:
1. #14 w/ 20A Circuit break
2. Flasher on the fuse board/box
3. Flasher behind the radio
4. All new front and rear light bulbs
5. New headlight harness
6. Hazard/ convertible top switch
7. Headlight switch
8. Lic plate LEDs



No running lights at all.
 

manicmechanic007

Mustang Master
Sep 26, 2017
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Start tracing wires
You got something unplugged?
Or you have a broken wire somewhere behind the dash maybe
 
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Blueinfan

Active Member
Mar 18, 2021
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Yes, headlights do work
front and rear Hazards work when activated, I could hear the clicking going on the flasher on the fuse box
front and rear turn signals work when activated, I could hear the clicking going on the flasher under the radio
license plate lights work

I have replaced:
1. #14 w/ 20A Circuit break
2. Flasher on the fuse board/box
3. Flasher behind the radio
4. All new front and rear light bulbs
5. New headlight harness
6. Hazard/ convertible top switch
7. Headlight switch
8. Lic plate LEDs



No running lights at all.
 

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Blueinfan

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Mar 18, 2021
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Temecula
Added pictures of what the fuse box looks like, n two other pictures with two other wires with no connection n looks like a ground wire missing
 

manicmechanic007

Mustang Master
Sep 26, 2017
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Your car may not use all those connectors depending on options like cruise and clutch.
The big white one might be the key in ignition buzzer
I would have you check power to each socket and out of the headlamp switch for the no park lamps issue
The wrong bulbs a possibility?
Socket failure a possibility
 
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manicmechanic007

Mustang Master
Sep 26, 2017
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You should have a black with orange power wire into the switch
Then the brown is the exterior lamp feed that goes to each park lamp
 

Blueinfan

Active Member
Mar 18, 2021
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ok, so did some further testing.

As I mentioned the headlight harness is brand new from LMR.

1. With hazards on, the low coolant level indicator flashes just like the hazards
2. Driverside headlight flashes off/on like the hazards
3. if I turn off the hazards, and turn on the headlight the parking light is very dim
4. Checked the driver side marker light with a voltmeter and got 3.5 - 7.41 volts and nothing over while the car was on.
5. Replaced and test the new bulbs and replaced all the fuses.

Nothing was modified in the car. Just took out the old headlight harness and placed a new one.



BUT - Did upgrade to a new 1986-93 MUSTANG SVE 130 AMP ALTERNATOR FULL UPGRADE KIT - BLACK

 

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