73 F100 Electrical problems
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73 F100 Electrical problems
Hi, I’ve got a few electrical problems that I’m stumped on (1973 F100 Ranger XLT)... So the only things that work within the cab is the blinkers(no hazards), fuel gauge, and ignition. No dash lights, oil pressure, ammeter, wiper or anything. Sometimes the dash light decides to work but rarely. Any help would be appreciated. Thanks.
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From: Stanley, VA
First, check your fuses. The turn signal/no hazards, check and make sure you have two flashers, one for the turn signals and one for the hazards. Someone could've switched flashers to replace a bad one and never replaced it. No lights, turn the lights on and try turning the light switch **** clockwise, this brightens/dims or shuts off the instrument lights. Ammeter, it's a crapshoot if the ammeter will work at all. This was a poor design and quite often didn't work right from new. It was such a problem Ford issued a TSB on it back in the day.
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From: Stanley, VA
It never hurts to go through and clean the grounds, a lot of electrical problems can be traced to bad grounds. Do the headlights work at all? Unplug the dimmer switch, turn the headlights on and check that one of the three wires has voltage. If there isn't any, the problem is further up, possibly the headlight switch itself. If there is voltage, the dimmer switch would be suspect.
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Yes, the headlights work as well as all external lights... When you said to make sure one of the three wires has voltage, where It that at? My dimmer switch has eight wires coming off of it. I did go in and clean my grounds and manged to fix the instrument cluster and wipers.
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Joined: Apr 2009
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From: Stanley, VA
Yes, the headlights work as well as all external lights... When you said to make sure one of the three wires has voltage, where It that at? My dimmer switch has eight wires coming off of it. I did go in and clean my grounds and manged to fix the instrument cluster and wipers.
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From: Angier, NC
Yes, the headlights work as well as all external lights... When you said to make sure one of the three wires has voltage, where It that at? My dimmer switch has eight wires coming off of it. I did go in and clean my grounds and manged to fix the instrument cluster and wipers.
I was talking about the dimmer switch wiring. My '73 only has three wires (red w/ yellow trace-power, red w/ black trace-low beam, green w/ black trace-high beam). Unplug the dimmer switch, turn the headlights on and check for voltage at the red w/ yellow trace wire, you should have 12 volts.If the headlights don't change from low to high or back my first suspicion would be the dimmer switch.
The dimmer switch is on the floor and should have 3 wires in the plug.
The head light switch is in the dash and could have the 8 wires, I never counted them on my 81 F100 to know.
When you checked the fuses I would pull all of them and wipe the metal ends & the holders.
Sometimes they get a film and the connection is poor even if the fuse looks good.
The other thing on the head light switch the dimmer part gets the same way. Turning it back n forth will sometimes get the dash lights to work other wise replace the switch.
Dave ----
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forrestjoy
1973 - 1979 F-100 & Larger F-Series Trucks
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Jun 19, 2007 09:08 PM
