I have a 76 F!50. Changed out headlight switch and fuse is good.
Have no gauge lights. Turn signal idicator flashes but when I pull out the light switch **** turn signal still flashes but indicator light stays lite but does not flash. No ash tray light either.
Where do I start to resolve problem. I am in the process of restoring truck and this problem has to be fixed.


Thanks

 

Instrument cluster lighting is the blue/red stripe wire.

You will have to remove the cluster to see the back of it.

 

Once I remove the cluster where is blue/ red stripe wire attached. Does this wire run back to the switch?.

 

This blue/red stripe wire runs to all the place that have a small bulb for lighting.

Ash tray, heater control,OEM Radio etc.

The cluster has either a 14 pin or 18 pin connector attached to it.
In this connector you will find the cluster lighting wire, it then powers the cluster lights thru the prinbed circuit.
You are going to be checking the Printed circuit for cracks and breaks.

You will also be checking the rest of this wiring circuit for power to the accessories.

But, before you do this, check the fuse for continuity with a VO meter. Not a visually.


EDIT:
If you go to this thread

https://www.ford-trucks.com/forums/s...hreadid=192856

and scroll to the bottom you will link's to illustrations of the backs of clusters

 

Thanks for the insight.
I will pull the cluster out this weekend.
If the printed board is bad would it cause the ashtray light and heater control not to light up.

I did check fuse with Volt meeter and it is good.

 

Hello wiz,
Mine did the same thing. Have you replaced the socket on the T-sig/marker light that is causing you problems? Here was my symptoms. My indicater on the right T-sig would stay illuminated when the light switch was pulled onto the on position. When lights were off, the T-sig indicater would work as specified. But, the T-sig would flash slowly. I worked on it for several hours. Checked the grounds on the radiater housing. Chased the wires. No luck. Went back to the socket. Did a better inspection this time. The socket was the problem. Fixed the ground inside the socket with a jumper wire. T-sig now works as specified at all times now. The instrument lights did not work on my truck. I traced this problem after several hours to the 3 amp fuse. I cleaned the post's, replaced the fuse, turned on the lights and still no dashlights. The problem was a radio wire shorting everything out. As soon as i turned on my lights, the fuse would blow. Seemed I was overlooking the fuse after it blew. Thought I had fixed that area, but went back and yanked all the P/O's wireing out replaced the fuse again and walla. Dashlights have not failed for several miles. Hope this helps you out a little. On aother note. I had dirty fuel in the front tank. The back tank is going to be replaced because all the rust in the tank. Well, I ran the front tank down to where I thought it would be empty and put in a cheap bottle of oriellys fuel additive. I have a glass filter. The fuel was mucky brown. Drove the truck five miles, pulled over to look at the filter. WOW, crystal clear! The truck started running smooth at Idle and full throttle without a miss. I'm trying to run it dry and add two more gallons and clean again. Point is, I did not believe additives work. Now I due. .99 cents a bottle is not bad. Good luck

 

If the printed board is bad would it cause the ashtray light and heater control not to light up.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

They are the same circuit but.... have seperate harnesses.

Check the fuse first.
If it is blown and you replace it ..then it blows you are going to have to disconnect different places on that circuit one by one until the fuse stops blowing.

Did you see my illustrations in the other thread in this forum?

 

I did see your diagram.
I am pulling the dash apart today and tracing the Blue Red wire.
Will advise my findings

Thanks for your help.

I still am struggling with the T/S indicator.
Everything works fine but when I turn on the lights the right side front and back turn signals do not flash.
I replaced the bulb sockets. but still have problem
Emergency flashers work okay
Got any ideas

WiZ