79 Ford 2wd wierd electric problem
Freshman User
Joined: Aug 2001
Posts: 25
Likes: 0
From: Greenup,Ky
79 Ford 2wd wierd electric problem
Howdy folks,
I recently rebuilt my 79 truck as a show & go. I'm almost finished but I have a small electrical glitch I cant find...
When I open the door the dome light wont come on unless the dash heat/ac selector is on A/C or Hi/low. Weird Eh?? I have replaced the switch hoping that was the fix but no change. Anyone have any ideas? I still have all the plastic trim,radio & dashpad off of the dash so getting into the dash wiring is no problem.
Thank Ya Kindly
I recently rebuilt my 79 truck as a show & go. I'm almost finished but I have a small electrical glitch I cant find...
When I open the door the dome light wont come on unless the dash heat/ac selector is on A/C or Hi/low. Weird Eh?? I have replaced the switch hoping that was the fix but no change. Anyone have any ideas? I still have all the plastic trim,radio & dashpad off of the dash so getting into the dash wiring is no problem.
Thank Ya Kindly
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
79 Ford 2wd wierd electric problem
Howdy folks,
I recently rebuilt my 79 truck as a show & go. I'm almost finished but I have a small electrical glitch I cant find...
When I open the door the dome light wont come on unless the dash heat/ac selector is on A/C or Hi/low. Weird Eh?? I have replaced the switch hoping that was the fix but no change. Anyone have any ideas? I still have all the plastic trim,radio & dashpad off of the dash so getting into the dash wiring is no problem.
Thank Ya Kindly
I recently rebuilt my 79 truck as a show & go. I'm almost finished but I have a small electrical glitch I cant find...
When I open the door the dome light wont come on unless the dash heat/ac selector is on A/C or Hi/low. Weird Eh?? I have replaced the switch hoping that was the fix but no change. Anyone have any ideas? I still have all the plastic trim,radio & dashpad off of the dash so getting into the dash wiring is no problem.
Thank Ya Kindly
Could it be that the dome light is getting its power from the ac switch? There is a circuit off the switch that puts 12volts to the idle solenoid of the carb to bump up the idle speed when the ac is on, prevents the truck from stalling due to the increase demand on it by the ac compressor.Try finding the wiring for the dome light and make sure it is connected to a fuse that has power on it all the time, regardless of key position.
Sparky
Freshman User
Joined: Aug 2001
Posts: 25
Likes: 0
From: Greenup,Ky
79 Ford 2wd wierd electric problem
Thats what I cant figure out I checked the fuse - its #2 in the manual a 3 amp shorty & isnt tied into the a/c circuit. I found where the wire goes into the a-pillar up to the dome light, I have a 600 Holley vac secondaries on it so there isnt a switch on the carb anymore.
I played with it some more before I headed of to work & I was wrong about the hi/lo switch it only works(dome light) when on a/c.it can be turned on & off with the regular light switch. I'm getting power to & thru the fuse & all other items that are tied into this supply work fine such as dash lights & so on without the dash set to a/c.
I'll try to go backwards from the a/c power & see where I end up.
Thanks for the scoop & I'll keep looking!!
I played with it some more before I headed of to work & I was wrong about the hi/lo switch it only works(dome light) when on a/c.it can be turned on & off with the regular light switch. I'm getting power to & thru the fuse & all other items that are tied into this supply work fine such as dash lights & so on without the dash set to a/c.
I'll try to go backwards from the a/c power & see where I end up.
Thanks for the scoop & I'll keep looking!!
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
79 Ford 2wd wierd electric problem
My book shows the dome light as a 15amp fuse, the 3amp one is shown as feeding the dash lights.
According to this manual the dome light is fed from the same fuse, several different ways. First is thru the headlight switch; second is by a separte wire from the same fuse thru the rh door switch; and third is a wire tapped off the input wire to the headlight switch then thru the lh door switch.
So pull the fuse for the domelight and you shouldn't get a domelight when the door is opened or the headlight switch is turned. If you dont get a light, and you shouldn't, turn the ac switch on and see if you get a light. If the dome light works now then a wire is hooked up incorrectly.
Happy hunting
Sparky
According to this manual the dome light is fed from the same fuse, several different ways. First is thru the headlight switch; second is by a separte wire from the same fuse thru the rh door switch; and third is a wire tapped off the input wire to the headlight switch then thru the lh door switch.
So pull the fuse for the domelight and you shouldn't get a domelight when the door is opened or the headlight switch is turned. If you dont get a light, and you shouldn't, turn the ac switch on and see if you get a light. If the dome light works now then a wire is hooked up incorrectly.
Happy hunting
Sparky
Lead Driver
Joined: Nov 2000
Posts: 6,628
Likes: 345
From: Albuquerque
79 Ford 2wd wierd electric problem
Usually when you have strange interaction problems it will turn out to be a bad ground. Which one I cannot say.
1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything
1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything
Thread
Thread Starter
Forum
Replies
Last Post
