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| Turn signal fuse keeps blowing (Page 1/2) |
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ethan555
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SEP 23, 07:08 PM
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The turn signal fuse on my 87 gt keeps blowing. It pops as soon as I start the car. I have the dash all off. Where is a good place to start to find this short?
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Cajun
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SEP 23, 08:12 PM
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I would suggest that you start by removing all the bulbs associated with the system. Then see if the fuse blows. If not, then replace a bulb at a time until the fuse blows. That will be your trouble shooting starting point.
If the fuse still blows with the bulbs removed them you have a bigger issue. You will have to refer to the wiring diagrams.[This message has been edited by Cajun (edited 09-23-2018).]
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ethan555
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SEP 23, 08:28 PM
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| quote | Originally posted by Cajun:
I would suggest that you start by removing all the bulbs associated with the system. Then see if the fuse blows. If not, then replace a bulb at a time until the fuse blows. That will be your trouble shooting starting point.
If the fuse still blows with the bulbs removed them you have a bigger issue. You will have to refer to the wiring diagrams.
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The fuse blows with out switching on the turn signals or putting it in gear (manual transmission) all I have to do is turn the key and it blows. I’m thinking it’s something with the wiring possibly. I’m not sure what trouble areas to look at to find the short. This is a 3800 engine swap and I’ve only recently had this problem. Currently the whole dash is off with nothing looking shorted and the plug next to the stock battery location looks ok too. What else is left?
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Shho13
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SEP 24, 12:30 AM
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Makes sense, the circuit is only receiving power when the ignition switch is in run/bulbtest/start.
As long as the "turn hazard switch assembly" isn't the part that is shorting internally, the short wouldn't be any of the blinker lights, or the circuits to them; they are out of the circuit until you physically flip the switch for left, right signal (look at the circuit, you can see how I highlighted the flow of power). It seems you can rule out/in the turn signal switch, the circuitry after it, and the flasher unit by simply removing the flasher. If after you remove the flasher and the fuse still blows, that isolates a whole lot of the circuit; and would mean that the short may be in the "back up lights" section for your hunt for a short, as that is spliced off that circuit before the flasher... If the fuse continues to blow after removing, then you know the short is on the side of the flasher, etc...
Here's the diagrams for you to look at to help you along... I highlighted the wire colors, while also guiding the flow of power to you, so that you a basis of what wires you should be focusing on while you look the circuit over for shorts...
------------------
"Discord"
Red 1988 GT under restoration!
Let's Go Mets!
( ͡° ͜ʖ ͡°)[This message has been edited by Shho13 (edited 09-24-2018).]
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TikiBird
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OCT 26, 05:44 PM
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Were you able to solve the issue. My '87 GT Auto is doing the same thing suddenly! Pulled the bulbs out of the back and disconnected the wiring harness next to the battery. Still blows. Next step in the investigation is to look at 2 things:
1) Turn signal switch
2) Reverse switch. Where is the reverse switch on automatics?
| quote | Originally posted by Shho13:
Makes sense, the circuit is only receiving power when the ignition switch is in run/bulbtest/start.
As long as the "turn hazard switch assembly" isn't the part that is shorting internally, the short wouldn't be any of the blinker lights, or the circuits to them; they are out of the circuit until you physically flip the switch for left, right signal (look at the circuit, you can see how I highlighted the flow of power). It seems you can rule out/in the turn signal switch, the circuitry after it, and the flasher unit by simply removing the flasher. If after you remove the flasher and the fuse still blows, that isolates a whole lot of the circuit; and would mean that the short may be in the "back up lights" section for your hunt for a short, as that is spliced off that circuit before the flasher... If the fuse continues to blow after removing, then you know the short is on the side of the flasher, etc...
Here's the diagrams for you to look at to help you along... I highlighted the wire colors, while also guiding the flow of power to you, so that you a basis of what wires you should be focusing on while you look the circuit over for shorts...
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fierosound
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OCT 26, 05:55 PM
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| quote | Originally posted by TikiBird:
2) Reverse switch. Where is the reverse switch on automatics? |
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Unplug the harness from this switch on your transmission. Any change?
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My World of Wheels Winners (Click on links below)
3.4L Supercharged 87 GT and Super Duty 4 Indy #163[This message has been edited by fierosound (edited 10-26-2020).]
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TikiBird
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OCT 27, 04:12 AM
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Sorry. I'm having trouble picturing where that is on the transmission. Are there any location photos? Been looking online...
| quote | Originally posted by fierosound:
Unplug the harness from this switch on your transmission. Any change?
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[This message has been edited by TikiBird (edited 10-27-2020).]
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theogre
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OCT 27, 01:34 PM
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open the deck lid. Stand to the left of engine bay and look down. Is only big electrical part on trans.
If you have cruise, is ~ under the servo and can have a bit harder time to see.
Auto trans N-switch rarely goes bad. Can get loose or out of adjustment but that won't blow fuses but often will cause starting problems.
Carefully Remove White "lock tab" before trying to unlock and remove the plug. Put white part back when done messing w/ the switch.
See my Cave, Neutral Safety Switch
To find shorts blowing fuses...
Take a blown fuse and if needed carefully open the test ports on top so can easy put volt meter or light bulb across the dead fuse.
Turn etc bulbs and sockets only blow a fuse when on.
But switches, relays, and power wires to them can blow a fuse just turning I-key to on or acc depending is light.
Also Bad switches etc can make a bulb be on when should be off is part of why pulling switch plugs can help.------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave
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fierosound
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OCT 27, 03:14 PM
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| quote | Originally posted by TikiBird:
Sorry. I'm having trouble picturing where that is on the transmission. Are there any location photos? Been looking online...
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At end of shift cable on transmission.
Shifting PRND21 rotates the shaft the switch is on through the positions.
 [This message has been edited by fierosound (edited 10-27-2020).]
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TikiBird
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OCT 27, 04:18 PM
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I think I see switch based on fierosound's photo above. I can't really reach it due to the cruise control and vacuum cannister in the way.
Yesterday, I pulled all of the tail bulbs (including reverse) and disconnected the wiring harness at the firewall (next to the battery). Wouldn't that have eliminated anything in the engine bay or tail lights? Anyway, the fuse still blew when I turned the car to the "ON" position. Was thinking my next step would be to disconnect the turn signal switch and see if the short goes away. But, I'm out of ideas. Am I on the right path?
Good idea on putting a bulb across an old fuse. I'll build that tonight.
| quote | Originally posted by theogre:
open the deck lid. Stand to the left of engine bay and look down. Is only big electrical part on trans.
If you have cruise, is ~ under the servo and can have a bit harder time to see.
Auto trans N-switch rarely goes bad. Can get loose or out of adjustment but that won't blow fuses but often will cause starting problems.
Carefully Remove White "lock tab" before trying to unlock and remove the plug. Put white part back when done messing w/ the switch.
See my Cave, Neutral Safety Switch
To find shorts blowing fuses...
Take a blown fuse and if needed carefully open the test ports on top so can easy put volt meter or light bulb across the dead fuse.
Turn etc bulbs and sockets only blow a fuse when on.
But switches, relays, and power wires to them can blow a fuse just turning I-key to on or acc depending is light.
Also Bad switches etc can make a bulb be on when should be off is part of why pulling switch plugs can help.
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[This message has been edited by TikiBird (edited 10-27-2020).]
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