Intermittent dash lights, radio, cab electrical problems will reproduce when emergency brake releases. 1973 F-350 Super Camper Special off frame resto...recent engine swap...has an intermittent short in the electrical that didn't start showing up until 3 months after the resto and engine swap was complete. You can be cruising along and then all of the sudden, noth'n...all cab electrical goes off but the engine keeps running. A short time later...back on! When you start it up and release the emergency brake (with a bang), often times the electrical will flash off for a brief second. There is no wire being pinched by the emergency brake. To confuse matters, last night the headlights where flashing on and off as I am rolling along...WITHOUT any problems with the cab electrical at the same time! My guess is there is some ground or fusible link that may be corroded or just not quite getting a good connection but I am not sure where to start looking. I have checked the engine to cab firewall ground and it appears secure with a good connection. I am thinking it has to be something on the firewall/fuse bus if it is sensitive to the banging of the emergency brake. Where should I start?

73SUPERCAMPERSPECIAL
-email address removed-

 

The first thing I would do is check your battery ground cable although it probably is not the culprit, what I would do then is disconnect the battery and then pull the fuse box and look for any loose or worn wires, make sure the rubber grommets in the firewall are sufficiently protecting the wires coming through. Also, make sure there aren't any cracks in the plastic body of the fuse panel. Electrical prob's can be a real nuisance as I am sure you are finding out. To my relief I figured out a problem of my own this morning, my front lights/blinkers/markers all work but I only have blinkers and license plate lights working out back... the bed isn't grounded... simple $3 ground strap and some new star washers and sheet metal screws will get me up and lighting. Look for surface rust anywhere wire meets body panel or frame. Also look for pinholes in your wire insulation or loose tape, that could be hiding internally corroded wire. When this "frame off" resto was done was the wiring harness replaced? You might also check the accesory lead from the ignition switch, could be it is loose, get the problem to happen and then reach under the dash and wiggle the wires independantly and see if you get power back, just be careful. and one more thing, if you use a multi meter to trouble shoot don't poke holes all over the wire, you will regret it when the wires all corrode. Good luck!!

 

I just had my dash out. I had to replace the Ignition switch, and deal with a lot of corrosion.
There are two ground wires just behind the light switch that are screwed to the steering column brace. They are behind the dash cluster. That column rust's and the grounds get corroded.

ALso, the dash lights are fed by the Rheostat on the light switch. That corrodes too. I used liquid wrench. Sprayed it on the Rheostat and exercized it and the lights became stable again.

There is a voltage regulater on the back of the Dash cluster. It'l go bad once in awhile, and all those connections for the little light bulbs will corrode as will the large connection for the dash cluster logic.

Watch out for the DImmer Switch too. It gets bad and the lights blink on and off while your driving.

Be sure to let us know what you find....

 

Whenever you find a ground connection clean it down to bare metal and use star washers and silicone dielectric grease on the mating surfaces.

Clean any other plug-in type connections you find with sandpaper and electric contact cleaner. use silicone dielectric compound on them to keep them from corroding again.

Check all of your crimp connections for any signs of heating, discolored or brittle insulation. Also check the crimps for any signs of corrosion. The best way to fix a crimp problem is to cut it out and crimp and solder a connector back on. Or get rid of the connector and solder the two wires together if it is a splice.

If you do use insulated crimp terminals, strip the wire back ~3/16" and dip it in silicone dielectric grease before inserting it into the crimp connector. squeeze some silicone into the connector ends also.

Use heat shrink tubing if you can to protect splices and connections. At least tape them securely with Good electrical tape... Not the cheap stuff.

DO NOT use those little blue plastic wire splices that you squeeze together with pliers. They are insulation displacement connectors that will corrode internally and can break the wire.

Clean all of your connections on your flex circuit on the back of your instrument cluster. Use silicone dielectric on all of the connections, bulb holders, and under the voltage regulator and connections.

 

This morning I started removing old wirenuts and soldering the connections under the dash where there have been years of old patch in type electrical projects (cb radios, trailer brakes, etc) and wiggling wires while the power was going off and on. I also was undoing any connections/harnesses and greasing them up. I pulled the ignition harness and a large black wire popped out of it. When I put the greased harness back on the ignition without the large black wire, there was no accessory type power. When I plugged the black wire back in to the harness…it was beautiful. POWER!



I have not been able to duplicate the short since! The best thing is that it only took about 30 minutes and no parts. I love easy fixes. Thanks for the help.



Frank