Slick 60's

The other day - of course at about 1a a ways from home - I took off from a light and since the truck was cold I nearly killed it. Well the truck didn't actually stall but I heard a loud pop and come to find out all the lights on the truck stopped working. The truck ran fine - was able to stop and restart, but every light on the truck was out. I did some research and found that all the fuses were blown or falling apart (yikes), so I bought a new headlight switch at the recommendation of other posts here, replaced all the fuses and now I have parking lights and turn signals but still nothing else.

Wiring is of course a mess underneath and hasn't ever been fully rewired - there are a lot of splices and errant wires. Yesterday I took out the instrument cluster to see if I could find the culprit but nothing looks fried and I can't find any additional fuses to investigate my lack of lights. What do check next? Truck is a 64 F250 and is stock underneath as far as I know.

Large black wire from the starter relay goes into the fuse block and powers the lights. Start there and follow it through the fuse block and to the switch. Somewhere you have a short. The light switch has a internal fuse that may be open?

The only common factors are the power from battery via relay battery lug, and the switch itself. A test lamp will be extremely handy to find where power is or isn't. The switch has a built-in circuit breaker for headlamps only, but it sounds as if you may not be getting power to the switch. Carefully check your firewall connectors as they are a common problem area. It sounds as if you may have had a short to ground, thus, inspection and verification of ALL grounds may be in order.
Paul

thanks guys. I'll get the tester out tomorrow and see if I can break this...

if you have parking lights power is coming into the headlight switch

i would look at the plug connection at the switch,its possible that some wires have backed out of the plug when reinstalling the switch.

also it would be good to inspect the dimmer switch, if it went bad there is no way for power to reach the headlights regardless of the headlight switch being good or not.

dimmer switch rheostat is built into the headlight switch, no?

Floor mounted dimmer switch or high beam switch power runs through it to the headlights

dvotion wrote:dimmer switch rheostat is built into the headlight switch, no?

yes.

theres a thin little tab that contacts the spring and then the dome light when turned all the way. sometimes the tab is bent and no contact.

old switches the spring can be crusty
it is possible to carefully remove the ceramic wheel and clean the spring.

Just to clarify: panel lamp dimming is via rheostat. Dimmer (high/low beam) is the floor mounted switch. I can't over-emphasize the importance of the grounds, especially after instrument panel removal! Current is pretty persistent, and will find a path, even if through another circuit.
Paul

ICEMAN6166 wrote:

dvotion wrote:dimmer switch rheostat is built into the headlight switch, no?

yes.

theres a thin little tab that contacts the spring and then the dome light when turned all the way. sometimes the tab is bent and no contact.

old switches the spring can be crusty
it is possible to carefully remove the ceramic wheel and clean the spring.

headlight switch is brand new - replaced to get parking lights working so I believe the rheostat is okay. I'm not sure if the floor mounted dimmer is even wired in at this point - will have to check that + grounds today.

As stated by others; no dimmer continuity, no headlamps! Hope it turns out to be simple and obvious. It usually is, but sometimes it takes a while to locate that "simple" fix!
Paul

is the high beam dimmer switch power continuity in the plug or in the switch ? Maybe thats confusing... I have had headlights - never high beams - I assumed they were wired out in a make shift fix over the years, and the dimmer switch plug has never been plugged into the floor mount switch even though it is there and the wiring is still intact as per OE.

continuity is thru the dimmer switch

normal wiring if the plug is removed from the switch no headlights at all

it is possible to use a jumper wire between the incoming power and one of the outgoing wires on the plug to get lights working if the dimmer switch becomes non functional while driving at night. i have had this happen before.

there is a very good fix for the headlights using relays

http://www.ford-trucks.com/articles/whi ... r-brights/

I'm trying to understand how I had headlights before without the switch being plugged in - no obvious jumper action - could an old headlight switch have been rigged somehow to make that happen?

dvotion wrote:I'm trying to understand how I had headlights before without the switch being plugged in - no obvious jumper action - could an old headlight switch have been rigged somehow to make that happen?

not unless theres a splice bypassing the dimmer

no telling what some people do to wiring, i have seen lots of strange things.

Thank you all for the massive amount of help - still working to fix it but this info is great. Will update when fixed.

If you can locate the three-wire plug for the dimmer switch somewhere around that area; might check to see if two of the wires are spliced, or a cotter pin or such jumpering across two of the terminals.
Paul

So...replaced the dash, sorted all the wires, got a new high beam dimmer and installed everything. The lights all work now up until the exact moment I press the brake pedal at which point the main 20a fuse (it is supposed to be 20a right) blows. Every time, ideas?

pretty sure the heater is the only 20 amp fuse.

somewhere when you press on the brake pedal, you are creating a grounding of a positive wire which will continue to blow fuses until you find the cause.

i have seen the wires for the turn signal switch that are inside the column tube go bad and if the one from the brake switch to the turn signal switch is bare inside the column and touching metal, it will blow a fuse whenever you step on the brake.

could be one of the wires running along the frame to the rear as well, although in this case it would also blow when a turn signal is used.

Turn signal would probably not blow a 20 amp quickly due to the load sensing of the flasher.
Paul