Dash Lights. not the typical issue
Senior User
Joined: Sep 2004
Posts: 484
Likes: 0
From: SC lowcountry
In the 88 manual power is supplied from fuse #4 (15A)( hot at all times) in dash to light switch then to fuse #17 (5A); then to instrument lights.
Remember that this power goes thru the rheostat for dimming dash lights and it can burn in twl or get corroded to point that no power will get to lights. Simplest is to replace light switch.
Remember that this power goes thru the rheostat for dimming dash lights and it can burn in twl or get corroded to point that no power will get to lights. Simplest is to replace light switch.
Thread Starter
|
Freshman User
Joined: Mar 2007
Posts: 26
Likes: 0
ok this is an old thread, I have been really busy and finally getting to it. I replaced teh headlight switch with a brand new one from autozone and advance autoparts, no change at all. What the hell can i be missing, the wiring is not hacked anywhere I can see. Thanks
Senior User
Joined: Oct 2005
Posts: 389
Likes: 0
From: Berlin, CT USA
This may seem stupid but you never know, on the switch in question, i have a 97 f250 hd and my switch rotates like a dimmer i can turn the dash light off completely if i wanted, u sure its rotated to illluminate just a shot in the dark.
Senior User
Joined: Nov 2007
Posts: 435
Likes: 0
From: Los Angeles, CA
Onebadcat,
What is your name?
Let's take this one step at a time. I am working from 1989 schematics published by Ford. It should be the same or very close to your 1990 vehicle.
The headlight switch is supplied 12v by a tan wire with a red stripe. This protected by fuse #4.
The headlight switch output is a light blue wire with a red stripe. It goes to fuse #10. The output from fuse #10 is also light blue with a red stripe.
The light blue wire with the red stripe goes to TWO splices: behind the instrument cluster; and behind the wiper switch.
The light blue red striped wire illuminates the instrument cluster, ash tray, heater A/C panel, radio, and dash panel switch labels.
All of these items ground together near the wiper switch.
1) Fuse #4 should be hot all the time at 12v. Is it?
2) Fuse #10 should be hot only when the light switch is pulled out. Is it? It can have any voltage to 12v depending upon the rotation of the light switch.
3) Do the ash tray or radio illuminate with the switch on?
Check these items with your meter or test light grounded to a dash support bracket. I'll check this thread tonight for your results.
What is your name?
Let's take this one step at a time. I am working from 1989 schematics published by Ford. It should be the same or very close to your 1990 vehicle.
The headlight switch is supplied 12v by a tan wire with a red stripe. This protected by fuse #4.
The headlight switch output is a light blue wire with a red stripe. It goes to fuse #10. The output from fuse #10 is also light blue with a red stripe.
The light blue wire with the red stripe goes to TWO splices: behind the instrument cluster; and behind the wiper switch.
The light blue red striped wire illuminates the instrument cluster, ash tray, heater A/C panel, radio, and dash panel switch labels.
All of these items ground together near the wiper switch.
1) Fuse #4 should be hot all the time at 12v. Is it?
2) Fuse #10 should be hot only when the light switch is pulled out. Is it? It can have any voltage to 12v depending upon the rotation of the light switch.
3) Do the ash tray or radio illuminate with the switch on?
Check these items with your meter or test light grounded to a dash support bracket. I'll check this thread tonight for your results.
Posting Guru
Joined: Mar 2007
Posts: 1,757
Likes: 2
From: Florida
Spike....that is NOT a stupid question...I answered a thread once where a guy had sold a ruck because he couldn't get the interior light off.....he bought a new one and all of a sudden had the same problem...there had to be about 18 responses and not a one responded with what i did.....I told him to turn the headlight *** a little to the right......that's what it was......there are never stupid questions or stupid answers...did no one read what 95x15 said where it clearly says..."Remember that this power goes thru the rheostat for dimming dash lights and it can burn in twl or get corroded to point that no power will get to lights. "
JR
JR
Thread
Thread Starter
Forum
Replies
Last Post
cadunkle
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
7
Jul 8, 2013 08:46 PM
Faded_Memories
1999 - 2016 Super Duty
7
Jul 7, 2013 01:25 PM
black58
1948 - 1956 F1, F100 & Larger F-Series Trucks
9
Aug 20, 2010 01:36 AM
whitesdford
1999 - 2003 7.3L Power Stroke Diesel
10
Jul 26, 2008 11:08 AM
75F250Colorado
1973 - 1979 F-100 & Larger F-Series Trucks
7
Nov 11, 2002 07:50 PM
