99 Dome Lights

[PaulZ]

I have 3 bulbs up there, left and right that work with the switch there, and an LED between them.
When does the LED work?

 

[Uncle Gump]

With the dome lamp switch and door ajar switches.

Might even activate with a key fob unlock command.

 

[PaulZ]

Hmm, doesn’t come on either way. Tried the LED on the battery, it works. Dash knob dulls the gauge bulbs so it’s working. Fuse?

 

[RonD]

1990 Ranger

There are 2 circuits in the main light switch dimmer, turn the knob clock wise all the way and you will feel it "click" and Dome light should come on
Key on or off doesn't matter, leave in that position and test for 12v on both terminals for Dome light bulb
(this also turns on the Cargo Lights, next to 3rd brake light, if you have that setup)

If its an LED bulb then it has a + and - terminal, unlike regular bulbs that work either way, so try the bulb both ways

In each door jamb, body side, is the Dome Light switch that activates the dome light when a door is opened
Get a new one for drivers door
Unscrew the old one and pull it out with its wire connector still attached
Unplug it and plug in the new one
Screw it back in
It will be sticking out too far, that is normal
Closed the door and that will push it back lower and SET IT for correct depth for your truck
Open the door and Dome light should come on

Dome light fuse is #1 in cab fuse box, 15 amp fuse
(Dash lights/dimmer use fuse 13)

The outer bulbs on dome light fixture are MAP LIGHTS, not sure if they are on the same fuse as Dome Light in 1990/1

1990 and 1991 should be the same fuse box lay out

 

[PaulZ]

Hiya RonD,

Sorry for the confusing title, it’s a 1999 Ranger, not 90-91.

Bit of progress.. the LED is polarity dependent, only works one way despite lack of markings. Is that original or someone put it in later? Anyway it lights with the dash knob all the way up to the click.

Still nothing on open doors. Where is the jamb switch, it’s eluding me? Neither door works it so probably something else..

 

[RonD]

That's why years are important, lol

1995 and up have the door open switch inside the door, not in door jamb
And its on the Latch unit at back side of the door but inside

There will be a Door Ajar light on the dash that will come on when either door is opened
If that's not working then previous owner may have unplugged it vs fixing it

Picture of the latch, removed, Door Switch is the white part he's holding: https://i.ytimg.com/vi/HyTFsi809Hs/maxresdefault.jpg

Its a twist lock to hold it in place so door latch must be loosened, not removed to twist out the old switch and install the new one
2 wire connector

In 1995 and up this switch is connected to the GEM(body computer) not the dome light
The switch is a ground path to GEM, the switch is OPEN(ungrounded) when door is closed, and Grounded when door is open

Because of the location of the switch at the bottom of the latch dirt and debris will run down when it rains and go into the switch, making it stick CLOSED or shorting it to Ground
This will cause the GEM to turn on the Door Ajar light AND the dome light all the time, key on or off doesn't matter

If you take the door panel off and unplug the switch then NO ground, so no Door Ajar light and no dome light, the EASY FIX, lol

There is also a Dome Light Relay that the GEM activates when door switch is grounded, but these rarely fail, so start with the door switch
And the Dimmer wheel also passes its 12v thru the Dome Relay so its likely not the problem if that works to activate the dome light

 

[PaulZ]

Thanks again Ron! Hoe much we paying you?

Get this.. so today the wife wants to go shopping. She opens her side, the dome light goes on! Couldn’t believe it, so I tried it 35 times myself. Drivers side still no go. I’ll pull the panel but no rush…

 

[RonD]

Drivers door switch is probably unplugged, it also activates the warning Chimes which many people do not like
"Key in ignition" chime
"Main light switch on" chime

If the switch sticks closed................then chime is on full time when driving because "Key is in the ignition"

 

[Curious Hound]

FYI. LED stands for Light Emitting Diode. A diode is an electronic device that only allows current to flow in one direction. So, all LEDs are directional. If, at first, it doesn't work, try flipping it around.

 

[PaulZ]

Wonder why no + - on that LED. Nothing on the mount either. Oh well.

Anyway, the cargo light does work. What isn't is the reverse lights. Manual 5 speed.

 

[RonD]

Usually its the bulbs that are burnt out for reverse lights not working
You never notice when 1 reverse bulb is burned out, lol, only when BOTH are burned out do you notice

In a 1999 automatic the reverse light switch is in the DTR switch/sensor on transmission shift arm
Fuse 27 in cab fuse box 15amp

 

[PaulZ]

Fuse 27 good. Took one bulb out, it’s Ok. It’s a stick shift.

 

[sgtsandman]

Fuse 27 good. Took one bulb out, it’s Ok. It’s a stick shift.

Take a look at the plug on the transmission and make sure it is properly seated, the wires aren't damaged, or the connector isn't cracked or corroded. On the Ranger transmissions I've worked on, it is on the driver's side about half way back. Two wires, if I remember correctly.

 

[RonD]

Yes, manual trans 2 wire connector, drivers side
Unplug it
Short the 2 wires together(12v IN and 12v OUT)
Turn on key
Reverse lights should be on
If not then test if the Purple/orange wire has 12v with key on, the IN
The Black/pink wire is the OUT to the bulbs

If shorting the 2 wires works then replace reverse switch in trans

 

[PaulZ]

Sorry for the delay.. shorted the switch wires, bingo! Tried to spray it inside, no luck. New one coming.
Thanks guys!

BTW I was at a gas station today, a younger (which ain’t saying much) gearhead says “wow a 4x4, that things worth bucks!”. News to me, Thought they ere common