Turn signal help
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Senior User
Joined: Mar 2013
Posts: 388
Likes: 2
From: Sandy Eggo
Turn signal help
I'm starting to struggle here...usually i'm pretty good with 12v
Turn signals are not working on my truck...but brakes, hazards and parking/running lights all come on. So i have ruled out bulbs, connectors, continuity to each light. The flasher is good, ive tried 3. All work ok on the hazard circuit and none work on the turn circuit.
I replace the turn signal switch, all wires and connections check out like they should; i followed this guide and these diagrams which have been very helpful to truobleshoot and rule evrything out.
Turn and Stop Lamp Diagnosis for 70's Ford Pickup .: Articles
https://www.ford-trucks.com/forums/1...ring-help.html
As soon as i move the turn signal switch to left or right, i lose all power to the blue wire that feeds +12v to the turn signal switch? What am i missing here?
Turn signals are not working on my truck...but brakes, hazards and parking/running lights all come on. So i have ruled out bulbs, connectors, continuity to each light. The flasher is good, ive tried 3. All work ok on the hazard circuit and none work on the turn circuit.
I replace the turn signal switch, all wires and connections check out like they should; i followed this guide and these diagrams which have been very helpful to truobleshoot and rule evrything out.
Turn and Stop Lamp Diagnosis for 70's Ford Pickup .: Articles
https://www.ford-trucks.com/forums/1...ring-help.html
As soon as i move the turn signal switch to left or right, i lose all power to the blue wire that feeds +12v to the turn signal switch? What am i missing here?
Post Fiend
Joined: Apr 2008
Posts: 8,261
Likes: 15
From: Big Sky Country
Sounds like the fault is in the switch itself, is this a new switch?
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Senior User
Joined: Mar 2013
Posts: 388
Likes: 2
From: Sandy Eggo
It has proper continuity on the 4 leads powering the corner lights in signaling positions. The hazards work fine, but as soon as you signal left or right the +12v signal to the blue wire disappears...?
Cargo Master
Joined: Nov 2009
Posts: 2,364
Likes: 118
From: starship enterprise
The ford book says to check the feed to the flasher, orange and yellow wire.
Next it says check power to the blue wire (mentioned earlier) If you are losing power here, then it say repair feed from flasher to switch.
Not to come over offensive, but are you sure you are checking the turn signal flasher, and not the 4 way flasher? There are 2 flasher units.
Next it says check power to the blue wire (mentioned earlier) If you are losing power here, then it say repair feed from flasher to switch.
Not to come over offensive, but are you sure you are checking the turn signal flasher, and not the 4 way flasher? There are 2 flasher units.
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Senior User
Joined: Mar 2006
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From: B.C. Canada
The ford book says to check the feed to the flasher, orange and yellow wire.
Next it says check power to the blue wire (mentioned earlier) If you are losing power here, then it say repair feed from flasher to switch.
Not to come over offensive, but are you sure you are checking the turn signal flasher, and not the 4 way flasher? There are 2 flasher units.
Next it says check power to the blue wire (mentioned earlier) If you are losing power here, then it say repair feed from flasher to switch.
Not to come over offensive, but are you sure you are checking the turn signal flasher, and not the 4 way flasher? There are 2 flasher units.
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Assuming 12 volts goes away at the BLUE wire for good, this sounds like there is a short downstream in the turn signal wiring. When this happens, the turn signal flasher can act like a thermal fuse. Your turn signal fuse should be preventing this, but if someone has replaced it with the improper rating or wrapped it in foil, you will see stuff like this happen.
Answer these two questions:
1) Is your turn signal flasher getting hot?
2) When voltage at the BLUE wire goes AWAY, what is the voltage on BOTH sides of the turn signal fuse?
Report your results. Don't replace any more parts until you answer all questions clearly and concisely.
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Senior User
Joined: Mar 2013
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From: Sandy Eggo
Answer these two questions:
1) Is your turn signal flasher getting hot? nope
2) When voltage at the BLUE wire goes AWAY, what is the voltage on BOTH sides of the turn signal fuse? 12v
Report your results. Don't replace any more parts until you answer all questions clearly and concisely.
1) Is your turn signal flasher getting hot? nope
2) When voltage at the BLUE wire goes AWAY, what is the voltage on BOTH sides of the turn signal fuse? 12v
Report your results. Don't replace any more parts until you answer all questions clearly and concisely.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Glad to hear you got it worked out. My guess is that the old fuse was weakly blown, meaning it was intact enough to register 12 volts on either side when unloaded, but fell on it face as soon as you try to run current through it.
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