Blinking Headlights - dash and tailligts go out

[1970 Ranger]

Gentlemen,
My 1970 F250 Ranger headlights will sometimes begin blinking and the dash lights turn off and on in synch with the blinking headlights. When this is happening there is a fairly loud electrical switching sound (sender sound?) coming from just below or behind the glove compartment. The sound is coencident with the headlight blinking and the dashlights going on-and-off. Sometimes the dash and taillights will turn off completely, but the headlights will stay on. Varying the engine RPM doesn't change this. I have tested my charging system, it is fine, battery is good. My wiring is bone stock-original except for the intermittent wiper switch installed per this website. I have also by-passed the rheostat for the dash lights to keep them fully bright all of the time.

This happen to anyone else? What should I try? New headlight switch?

[Thunderfoot]

I'm guessing your truck is a Camper Special or has roof lights. See this thread for the clicking sound by the glove box. http://www.fordification.com/forum/view ... right+side it is a relay...
The flashing of the lights is caused by the Light Switch, it has a self-resetting circuit breaker built into it. They do get week over time and will cause this or if you put high wattage headlights in your truck you will get this problem as this circuit breaker (and wiring) is not big enough for the added load of the new high wattage headlights. This will continue to flash until it gets so hot that it will take longer and longer to re-set itself, and wear out the switch even more.

[1970 Ranger]

Thanks for the reply T-Foot!!
You're right, it is a C/S and I do have a cargo light/high brake lite combo above the back window.

So, I ought to replace the clicking relay. I also have AC, will I still be able to get to the relay without too much fuss?

[Thunderfoot]

The Relay is clicking because of the power loss from the light switch, that is the relay itself clicks when you turn the lights off and on (power from the light switch going out from the circuit breaker in it tripping and resetting) That relay is what controls the power to the marker lights on the fenders (camper special) the light switch controls the switching of the relay on/off and all the other lights you have going out...
Your problem is the light switch itself and/or to high of watt headlights (after market bright Halogen headlight bulbs)

[fordman]

that is not a high brake lite combo unless it was added by someone to do that function.

[marxtoys]

.......
Your problem is the light switch itself and/or to high of watt headlights (after market bright Halogen headlight bulbs)

I have had a shorted dome light wire cause the problem described.

[1970 Ranger]

Gentlemen,
I am trying to remove the lighting switch. I've removed the tank selector switch to get to the lighting switch and the lighting switch is unplugged. I am depressing the knob/shaft release button on the switch, but cannot remove the knob/shaft from the dash. I can feel the little spring button move as I try to pull out the shaft, but the shaft won't come out.

What am I doing wrong?? Thanks

[Thunderfoot]

You are doing it Right they can just be a bugger sometimes... Try pushing in the knob and then push the release button down, then pull the knob and wiggle, push/pull...

[fordman]

you have to push prety hard sometimes they just wont let go. i have always had to press pretty hard for them to release.

[1970 Ranger]

Gentlemen (and Ladies?)
I replaced the lighting switch with a new one, and the clicking problem got worse. Then I installed a 40A relay after the lighting switch and ahead of the dimmer switch, getting power using 10 GA new wire directly from the battery-starter terminal block. At first the clicking persisted then it seems to have gone away this week... jury is still out, but it looks like a good fix.

Couple of things that might help someone else in the future.

1. For some reason(?), the lighting knob easily pulled right out as soon as I reconnected the block plug (the thing with all the wires), and pushed the button, of course.

2. Use double sticky foam tape to stick the new spacer between the new lighting switch body and the back of the dash. If not, you need the fingers of a Pianist (that's a person who plays a piano) to finagle the spacer in between the switch frame and the dash. Or, if you are an engineer type, you can use 2 each, 1/8" dia, 1/4" deep pop rivets to do it really right. However, contrary to my advice, I have now done it the hard way on both of my 1970 f250's.

3. Installing the relay is a REALLY GOOD IDEA for anyone. The headlights and running lights are all much brighter, the interior lights are brighter. Basically, all of the things that get power thru the lighting switch just work much better. I stronly recommend this upgrade. I used a 40AMP 5-pin Bosch-type relay, removing the hot lead between the lighting switch to the dimmer switch plug, female connnector and all (a yellow/red wire), unravelled this lead from two wires for the normal/bright headlings, inserting this stock wire with female connector into the relay; inserting a new female connector into the dimmer switch plug with the heavy guage wire from the relay. I was able to install the relay between the parking brake release and the kick panel (not much room, but the best spot). If you are lucky, you can wedge the tab on the relay between the sheet metal "L" bracket that connects the kick panel to the bottom of the dash. Then put a 3/4" #8 self tapping sheet metal screw us thru all 3 layers of the sheet metal, the "L" bracket, the relay tab and the bottom of the dash... sweet installation if I must say so myself. Here is the relay, you can get it at Electronics Plus in San Rafael, CA for $7.50. It's a standard 5-pin Bosch type relay.

http://www.electronicplus.com/prodSearc ... mit=Search

I went to all of the Auto Parts Stores, NAPA, CARQUEST, and, yes, even KRAGEN. They had no idea what I wanted and tried to sell me a honda 20A relay for $37.95... no thanks....

Next I'm going for reconnecting my wiper washers and fixing my backup lights... perhaps some driving lights with additional relays sometime before deer season.

Thanks for all of the help, especially Thunderfoot..

[James72]

I would also look for a short somewhere, if it went away by itself, it will come back by itself
likely a rubed through wire somewhere