85 F150, strange wiring behavior after turn signal switch replacement
Thread Starter
|
4wd Low
Joined: May 2025
Posts: 14
Likes: 1
85 F150, strange wiring behavior after turn signal switch replacement
Replaced the turn signal switch in my 85, and now having really wierd electrical behavior.
When you turn the key on, it immediately pegs the amp meter to full discharge. Tons of power going through but I can't figure out where it's going.
When I turn the key to start, it doesn't turn over until I turn the key off, when it starts turning over and doesn't stop. Only way to stop it is to pull the trigger wire off the solenoid to cut power and then it'll stop, and you can hook it back up without it turning over.
For some reason, disconnecting the battery does NOT have the same effect, it'll start turning over the second you reconnect the battery, it only stops when disconnecting the trigger wire.
When I started it, it rans on like 2 cylinders, and after a bit of running, it melted the cluster where the amp meter is.
I have 400 ohms of resistance between the starter wire and the positive terminal so clearly I have some short somewhere between the ignition switch and the solenoid...
I noticed that if I jiggle the shifter in park it acts like I'm turning the key, so I'm thinking that maybe somehow the reverse light circuit is shorted to the starter safety? Not sure, just a thought on my end.
I'm gonna try to disconnect the reverse light switch and see if it does anything for me, if not, I'll chase wiring.
When you turn the key on, it immediately pegs the amp meter to full discharge. Tons of power going through but I can't figure out where it's going.
When I turn the key to start, it doesn't turn over until I turn the key off, when it starts turning over and doesn't stop. Only way to stop it is to pull the trigger wire off the solenoid to cut power and then it'll stop, and you can hook it back up without it turning over.
For some reason, disconnecting the battery does NOT have the same effect, it'll start turning over the second you reconnect the battery, it only stops when disconnecting the trigger wire.
When I started it, it rans on like 2 cylinders, and after a bit of running, it melted the cluster where the amp meter is.
I have 400 ohms of resistance between the starter wire and the positive terminal so clearly I have some short somewhere between the ignition switch and the solenoid...
I noticed that if I jiggle the shifter in park it acts like I'm turning the key, so I'm thinking that maybe somehow the reverse light circuit is shorted to the starter safety? Not sure, just a thought on my end.
I'm gonna try to disconnect the reverse light switch and see if it does anything for me, if not, I'll chase wiring.
FTE Legend
Joined: Nov 2015
Posts: 30,992
Likes: 4,140
From: Angier, NC
Is this a tilt wheel? Well if it was me I would be pulling the wiring in the column apart for a good look over as that was the last thing you were messing with
It should have been just the turn signal wiring and nothing else so dont know why it would have caused the problems you are having but it has to be there.
Dave ----
It should have been just the turn signal wiring and nothing else so dont know why it would have caused the problems you are having but it has to be there.
Dave ----
Lead Driver
Joined: Jun 2013
Posts: 5,693
Likes: 1,174
From: Tolland, CT
Cargo Master
Joined: Mar 2008
Posts: 2,590
Likes: 212
From: Washington
I really can't make any connections to the list of problems, from post 1, to your turn signal replacement.
If you thought it was related to the recent turn signal replacement, why didn't you just unplug the turn signal connector.... Before things started to melt down.
So let's take this a bite at a time.
1) First the easiest . If you remove the battery terminal, while the starter is spinning, the starter solenoid should UNLATCH. If it didn't, it is sticking closed.
2) In order to melt the amp meter, you have to have a problem with your alternator wiring harness. Remove the negative battery terminal, then remove and inspect the harness. Look closely at the splice points. They are the round rubber cylinder shaped thingies... . This is where the AMP METER shunt is located.
More information here, regarding the AMP meter shunt.
https://www.ford-trucks.com/forums/1...olt-meter.html
Do you still have a 1G stock alternator?
Any wiring mods or updating?
Jim
If you thought it was related to the recent turn signal replacement, why didn't you just unplug the turn signal connector.... Before things started to melt down.
So let's take this a bite at a time.
1) First the easiest . If you remove the battery terminal, while the starter is spinning, the starter solenoid should UNLATCH. If it didn't, it is sticking closed.
2) In order to melt the amp meter, you have to have a problem with your alternator wiring harness. Remove the negative battery terminal, then remove and inspect the harness. Look closely at the splice points. They are the round rubber cylinder shaped thingies... . This is where the AMP METER shunt is located.
More information here, regarding the AMP meter shunt.
https://www.ford-trucks.com/forums/1...olt-meter.html
Do you still have a 1G stock alternator?
Any wiring mods or updating?
Jim
Thread
Thread Starter
Forum
Replies
Last Post
nlareau
1973 - 1979 F-100 & Larger F-Series Trucks
15
Jun 30, 2011 11:28 AM
mark78f150
1973 - 1979 F-100 & Larger F-Series Trucks
6
Jan 9, 2001 12:43 PM
