1968 Fuse Issue

[stangfan]

I have an issue that has me scratching my head. I just replaced the battery in my GT/CS. I took the car for a run, and noticed that my turn signals had I stopped working. They were fine before. When I got the car home, I found that my radio, trans light and back up lights also were out. Thinking the fuse was bad, I tried to pull that fuse. Since I don't bend very well, I always have problems under the dash. I got my neighbour over, and he found that I had managed to break the fuse. He got all the pieces out, put in the new fuse, and all of the functions of that circuit were still not working. He put a voltage meter on the fuse, and it was good. Then he checked the box. The left side clip had 12 volts with the key on accessory. The left side ground worked properly, and the circuit had continuity across the fuse. What are we missing? Is there a fusible link somewhere past the fuse box? I'm lost....:undecided

 

[franklinair]

The fuse you are describing (upper left corner of the fuse panel):
1.) With the key ON or Acc you should have 12 volts on BOTH ends of the fuse.
2.) Sometimes due to age the fuse clips get a corrosive buildup causing poor or no contact.
3.) Verify 12 volts on BOTH ends of the fuse, then verify 12 volts on BOTH fuse CLIPS.
I suspect poor contact in the fuse clip(s). If that proves to be the case, the clips can be burnished with a small wire brush or a small piece of sandpaper to remove any surface corrosion to assure good electrical contact.

(The voltage for this fuse comes from the IGN switch. Does the Heater Blower work OK? This will verify that the voltage IS coming from the IGN switch.)
Hope this helps. Let me know.

Neil

 

[stangfan]

Thank you Neil. The heater blower works fine.

I will see if my bendy neighbour will get in there with some sandpaper when he has time. I sure wish I was younger and more flexible. :wink:

 

[franklinair]

I know the feeling. :sad:
"Delegate" has become one of my favorite words.

Neil

 

[CaliStang68]

Thank you Neil. The heater blower works fine.

I will see if my bendy neighbour will get in there with some sandpaper when he has time. I sure wish I was younger and more flexible. :wink:

I find that if you roll some sandpaper onto the fuse and install fuse, remove, install, etc. it gets the rust out pretty fast. Just don't use too aggressive sandpaper because you will grind down the metal vice the rust.

Rick

 

[stangfan]

I find that if you roll some sandpaper onto the fuse and install fuse, remove, install, etc. it gets the rust out pretty fast. Just don't use too aggressive sandpaper because you will grind down the metal vice the rust.

Rick

Thanks for that. My neighbour is going to use his Dremel with a tiny wire brush attachment. He has used it on his vintage VW van for the same purpose. :grin:

 

[CougarCJ]

Thanks for that. My neighbour is going to use his Dremel with a tiny wire brush attachment. He has used it on his vintage VW van for the same purpose. :grin:

+1, That is how the guys in our electrical dept do it.

 

[stangfan]

Okay, my neighbour came over this morning and cleaned up the fuse connections on the #1 fuse controlling the turn signals etc. He put in a new fuse, and as soon as I turned the ignition key to accessory, the fuse popped. Could this be an ignition switch problem? Any suggestions?

 

[robert campbell]

My guess is turn signal switch. They were the weak system of many a GT/CS due to the extra load of powering 6 light bulbs vice 2 in a stock Mustang. There has been a bunch of posts on this issue. Here is one of them. It may look familiar!!

http://californiaspecial.com/forums/showthread.php?t=11874&highlight=turn+signal+switch

 

[stangfan]

My guess is turn signal switch. They were the weak system of many a GT/CS due to the extra load of powering 6 light bulbs vice 2 in a stock Mustang. There has been a bunch of posts on this issue. Here is one of them. It may look familiar!!

http://californiaspecial.com/forums/showthread.php?t=11874&highlight=turn+signal+switch

That was my thread. It was the ground behind the taillight panel that was the issue.

In this case, the turn signal switch was not on. The fuse blew when I turned the key to the accessory side.

 

[franklinair]

Disconnect the connector @ the bottom of the steering column. Put in a new fuse. Put the Ign Sw to Acc. This will determine if the T/S switch/circuits is the problem.

Neil

 

[stangfan]

Disconnect the connector @ the bottom of the steering column. Put in a new fuse. Put the Ign Sw to Acc. This will determine if the T/S switch/circuits is the problem.

Neil

Thanks Neil.

 

[robert campbell]

The turn signal switch does not need to be on if it is shorted and will pop a fuse. Neil's suggestion is right on.

Rob

 

[stangfan]

The turn signal switch does not need to be on if it is shorted and will pop a fuse. Neil's suggestion is right on.

Rob

That is the part that I didn't understand. Thanks Rob. I will do the test as Neil suggested.

 

[stangfan]

We just did the test as per Neil's suggestion. The t/s switch connector was unplugged, a new fuse put into the fusebox, and the key was then turned to accessory. The fuse immediately blew. I assume that this confirms that the t/s switch is NOT the problem. Is it possible that the ignition switch has gone bad? Nothing on that fuse was turned on. I did replace the ignition switch a little over 4 years ago It is a Scott Drake product. Maybe I should have gotten an NPD switch?

 

[franklinair]

The fuse in question gets power FROM the Ign Switch:
Current then goes through the fuse TO the Backup light Switch, and then to the Backup lights.
Current also goes to the T/S Flasher and then to the T/S Switch (which has already been eliminated).
Other than a shorted wire, the only 2 components remaining are the Backup light Switch & the T/S Flasher.
Can you locate the connector (at the firewall, inboard of the Master Cylinder) that feeds the Backup light switch, and unplug it? That can eliminate the B/U light switch.
(I hope its not a shorted wire- that's another trouble shooting process.)

Neil

 

[stangfan]

Thanks Neil. That fuse also powers the radio and transmission light. Are they likely culprits?

 

[stangfan]

Neil, I just looked under the hood. To the passenger side of the MC there are two connectors going through the firewall. Is the backup light connector the flat one or the squarish one?

 

[robert campbell]

The backup light switch is located on the side of the tranny. Neil is right on where the plug is. It is a 4 wire bugger that can be fun to disconnect. It also functions as a transmission lockout switch that only allows the car to be started in neutral or park for safety reasons. It is kinda a high wear item and susceptible to shorting out. Unplug the plug Neil suggest and that will eliminate it. My gut says not the radio or the tranny light.

Rob

 

[stangfan]

The backup light switch is located on the side of the tranny. Neil is right on where the plug is. It is a 4 wire bugger that can be fun to disconnect. It also functions as a transmission lockout switch that only allows the car to be started in neutral or park for safety reasons. It is kinda a high wear item and susceptible to shorting out. Unplug the plug Neil suggest and that will eliminate it. My gut says not the radio or the tranny light.

Rob

Thanks Rob. Which of the two connectors I mentioned is the backup light one?