04 ranger dash lights went out

[mja_ranger04]

Hello all, name is Mike, from Northern California, currently live in Denver, moving to Oregon soon.

I have a 2004 ranger, base model, and something happened while I was driving, at the beginning of a 6 hour road trip.
This is very specific, and I've searched all over to find answers.
Well, to begin, I was driving on the freeway and suddenly, smoke began to exit from the dashboard, just above the instrument cluster. It continued for some time, 10 or 15 minutes. Luckily I had all of my tools with me, so I pulled off the panels to get to all of the wiring, i didn't find anything burnt up. Well, darkness fell, and as i turned on my headlights, i discovered what the result was... The climate control and instrument lights stopped working, but blinkers and other lights work. I read this is common, and i swapped dimmer switch module, still no change.
I checked all fuses, they are fine. This is beyond the basics. What exactly happened?

 

[RonD]

Welcome to the forum

2004 was first year for the Smart Junction Box(SJB), its the body computer, replaced the GEM, its in the passenger side kick panel, fuse box is part of the SJB

Most of the controls are GROUND activated to prevent wires "smoking"/melting if a short occurs, worst case should be something comes on and then won't go off

The Dimmer and wiring to back lights only have power when Park Lights are on, park light relay activated
From fuse 1(F2.1) in cab fuse box, 5 amp
Diagram below

Test if fuse 1 is getting 12v with Park Light switch on, key doesn't have to be on
If it does then test Red/yellow wire at dimmer to see if it has 12v

If Park lights work then relay is OK but still need to test if fuse 1 is getting the 12v and then 12v at dimmer

 

[mja_ranger04]

Welcome to the forum

2004 was first year for the Smart Junction Box(SJB), its the body computer, replaced the GEM, its in the passenger side kick panel, fuse box is part of the SJB

Most of the controls are GROUND activated to prevent wires "smoking"/melting if a short occurs, worst case should be something comes on and then won't go off

The Dimmer and wiring to back lights only have power when Park Lights are on, park light relay activated
From fuse 1(F2.1) in cab fuse box, 5 amp
Diagram below

Test if fuse 1 is getting 12v with Park Light switch on, key doesn't have to be on
If it does then test Red/yellow wire at dimmer to see if it has 12v

If Park lights work then relay is OK but still need to test if fuse 1 is getting the 12v and then 12v at dimmer

Thanks Ron,
I am not skilled at reading wiring schematics, but can get by with instructions. I haven't performed your test yet, but can tell you that dimmer switch does turn on dome light when clicked up all the way. I tested the dimmer switch a few weeks ago and was getting 12v at the yellow/red wire, will confirm again.

 

[RonD]

Red/yellow wire and only with Park lights/head lights on

Light Blue/red wire is OUT to dash bulbs, 0v to 12v depending on dimmer wheel setting

The dome light power/switch is in the dimmer module but no connection to dash lights, its a separate switch inside, just FYI

If you unplug dimmer module and put jumper wire between Red/yellow and Light blue/red wires then turn on Park lights dash lights should come on full brightness
If not then light blue/red wire is the issue

Same Light blue/red wire runs from dimmer to each back lit device on dash, i.e. switches and climate control

 

[mja_ranger04]

Red/yellow wire and only with Park lights/head lights on

Light Blue/red wire is OUT to dash bulbs, 0v to 12v depending on dimmer wheel setting

The dome light power/switch is in the dimmer module but no connection to dash lights, its a separate switch inside, just FYI

If you unplug dimmer module and put jumper wire between Red/yellow and Light blue/red wires then turn on Park lights dash lights should come on full brightness
If not then light blue/red wire is the issue

Same Light blue/red wire runs from dimmer to each back lit device on dash, i.e. switches and climate control

Ok, so what could be the problem if that's the case?

 

[mja_ranger04]

Red/yellow wire and only with Park lights/head lights on

Light Blue/red wire is OUT to dash bulbs, 0v to 12v depending on dimmer wheel setting

The dome light power/switch is in the dimmer module but no connection to dash lights, its a separate switch inside, just FYI

If you unplug dimmer module and put jumper wire between Red/yellow and Light blue/red wires then turn on Park lights dash lights should come on full brightness
If not then light blue/red wire is the issue

Same Light blue/red wire runs from dimmer to each back lit device on dash, i.e. switches and climate control

Am i just checking for power or exactly 12v?
I've checked for continuity and the #1 fuse lights up. I have 12v at fuse and dimmer switch.

 

[RonD]

When testing voltage with volt meter
Turn on the key and test voltage at battery terminals, say its 12.4v, then that's what you should see on 12v wires in the cab

And on the Light blue/red OUT wire on dimmer?
If that has 12v with dimmer turned up then problem is that wire is bad somewhere, the smoke you saw

 

[mja_ranger04]

When testing voltage with volt meter
Turn on the key and test voltage at battery terminals, say its 12.4v, then that's what you should see on 12v wires in the cab

And on the Light blue/red OUT wire on dimmer?
If that has 12v with dimmer turned up then problem is that wire is bad somewhere, the smoke you saw

How do i test it with a multimeter? I know what setting, but where do black and red probe go?

 

[mja_ranger04]

So if that blue/red wire is burnt up, what can I do about that?

This smoking happened after i installed an aftermarket radio, and reconnected wires exactly as they were on previous radio unit. There were 2 wires for illumination, the orange wires, and I connected to the one blue/red wire on the factory plug. I suspected that was the culprit and disconnected them. I cant believe this happened, i have installed dozens of units but never seen this scenario before, with the 2into1 wires and the smoke.

 

[RonD]

Yes, that connection would be the culprit most likely

"orange" wires on radio would be manufacturer specific and not sure why there would be 2 of them???? back light bulbs don't need separate wires, is one of them suppose to be a ground for the lights?

5 amp Fuse 1 in cab fuse box should have blown if radio lights drew too many amps thru dimmer, but it didn't?
So most like scenario is that the orange wires sent voltage back thru the blue/red wire

The Blue/red wire has a few splices under the dash as it splits to the different devices it lights up

Fords wiring manual should have those locations and pathways
Seen here: https://www.amazon.com/Ranger-Wiring-Diagram-Manual-Original/dp/B00435N9OW

Ford sends out a Shop Manual Set for every year and every model to dealer shops, one of the books in that set is "Wiring diagrams"(called EVTM in 1998 and earlier)
Its often re-sold separately
You would need the 2004 Ford Ranger Wiring Diagrams book, no other year or model would have what you need
These are basically free to use since you can re-sell them when you are done using them or sell your the 2004 Ranger and no longer need it

One above is on Amazon but Ebay usually has them listed as well, they are all "used" so just get best deal you can

 

[mja_ranger04]

I dont know either why 2 wires on the aftermarket harness, have never seen it before.
Probably need to remove the dashboard for this one... Would you say?
It will be a project when i have a garage and dont need the truck. Thanks

 

[mja_ranger04]

Yes, I believe one orange wire was pos and the other ground.. Not sure why there would be 2, I've only ever seen 1. It was unnecessary to connect both.. I'm really still a novice at electrical, even after all these years... Oh well, some things are like that..
Thanks for the help
...so it sounds like I'll have to remove the entire dashboard to look for this burnt wire, yeah? It will have to wait until i have my own garage and dont need the truck.