Couple months back I noticed that my instrument lights didn't come on when I turned on the headlights. Thought it was the bulbs, got no where with that. Checked fuses and found nothing. I have gone all the way to getting a "new" instrument cluster, headlight switch and dimmer switch from the local junkyard thinking that it would help! Nothing seems to change! Today I had the lights on while running around checking voltages and noticed that the damn running lights in the back are also not on!

Any day where to start? I have the dash all torn open right now and can get at anything I need and have a voltmeter.

Thanks for the help!

P.S. It is a 2004 Ford Ranger with the 4.0L engine, 5 speed transmission, and the old owner obviously changed the instrument cluster before (it had the designators for an automatic).

 

There is a Park light relay inside the SJB(smart junction box), its the cab fuse box unit, behind kick panel

SJB is the body computer, replaced the GEM

When you turn on the light switch the Park Light relay should close and that sends 12v to the dimmer and parking lights(all 4) plus license plate lights

Fuse 31 powers relay and all these lights
Sub fuse 1 powers dimmer wheel from fuse 31

The park light relay is embedded in the SJB not a serviceable part, but maybe its just some corroded wires on an SJB connector, a common issue

Article here with pictures of the SJB: https://www.therangerstation.com/tec...horn_mod.shtml
This is just so you know what the SJB is
The connectors have levers that you pull back and that lifts them away from the slot

The dimmer power and rear parking light power use connector 2280C
Front park lights use connector 2280A
So if front park lights are working then Parking light Relay is OK, its most likely connector 2280C has some corrosion

Connectors labelled here: https://www.2carpros.com/images/ques...7/original.jpg

The relays on the front of the SJB may or may not be there, they were used on some models but usually not on Rangers

 

Thanks for that! I took the SBJ out and found some corroded connections where you suggested to look. Cleaned them up (and found a faulty fuse connection for something unrelated) and reinstalled but still have nothing. I initially forget to disconnect the battery when I did this, but quickly stopped and went and made sure I had no power. I found no blown fuses on that fuse box, but continue to have no luck with the lights! Is there anything else you can suggest checking? Is there a way to test for a bad SBJ? Also do you know where to buy one if it is bad? Thanks!

 

Do the Front Park lights work?

That tells you if the Park light relay is working

 

I just went and checked and no parking lights work! The only working lights I have are the headlights, the one at the top of the cab that lights up when you open the door, and the indicators. I definitely can't drive this truck until this gets fixed.

 

No, not at night anyway, lol

Below is the diagram for the park light relay

The relay has 12volts all the time from fuse 31
The main light switch GROUNDS the park light relay to activate it, using the white/black stripe wire on C2280D

If you were to Ground that white/black wire with a jumper, at main light switch or SJB you should hear the park light relay click inside the SJB
The white/black wire should also show 12volts if tested with Volt meter, at main light switch or SJB connector, all the time

Diagram 2 is the one with park light relay

You can replace SJB from a 2004 and up Ranger with the same options, i.e. power windows/door locks

 

So the white/black wire has power to it, but I didn't get a rely clicks when it is powered up. Any idea where I can get a replacement SJB from? My Google searches seem to come up empty.

 

Did you try grounding that white/black wire to get relay to click, it could be main light switch ground is bad
White/black wire is not a "live" 12v wire, the voltage you see is passing thru the relays coil, so its not a short when grounded
And when grounded the park lights and instrument lights should come on so have a look

Wrecking yard

Try car-part.com

2004
Ford Ranger
Part is "computer box NOT engine"
Then select your area
Then select "multifunction, (RH kick panel)............."<<and with or without keyless entry, which ever you have

Then search

They run about $50-$60 in my area, they are light as well so don't cost that much to ship
Also see if it has Power window/locks, not sure if all SJBs are the same for that

 

Thanks for your help! I just called the Ford dealership about the part and they mentioned needing to get it reprogrammed. Is that true or is it dealership BS?

Once again thanks for all of your help!

 

A new one would probably need that, a used one would already be programmed, which is why you want to match options, like keyless entry and power windows

The SJB is not part of the anti-theft system so doesn't need to be matched with vehicles engine computer or PATS system

 

Ok so I played around with the SJB some more and found that a fuse had blown out since I last went through the fuse box (pre-cleaning the SJB connectors). It was fuse 31 (parking lamps). So I replace the fuse and it promptly blows out. I put a 25 A fuse in instead and that seems to work, but the rear park lamps are awfully dim. I am guessing I probably have some sort of grounding issues and/or those connectors still need some cleaning. Still, at least I finally have dash lights!

Thank you so much for your help! It really was a god send to have someone to tell me to even look at the SJB more.

 

Please come back and let us know when your truck burns to the ground.

NEVER replace a fuse with a higher rated fuse

 

Since you know about the connectors on the SJB now, you could pull the one connector that feeds 12v to rear park lights and also the other connector that feeds the front park lights
rear park light wire also powers license plate lights, which can corrode

Before starting pull fuse 31, then test with volt meter to see which "leg" is 12volt and which "leg" is LOAD(not 12v)
You can hook an OHM meter to the LOAD leg and then to a Ground, should see LOW ohms, a short, under 5 ohms
Then unplug connectors, or you can unplug bulbs if you have a suspect, when ohms go higher then short has been removed

Some people add trailer connector wiring to existing systems, these connection can corrode, so maybe have a look if there is a trailer wire connector, follow it back to the splices

Park light are rated as 8watts, so at 12volt that should be 18ohms
brake light/turn is 27watts so 6ohms, but isn't on this circuit

 

Yeah I know replacing a fuse with a higher rated one is bad news. It was actually just the last fuse I had left and I wanted to see if it would pop again!

Testing the resistance from the LOAD leg of fuse 31 to the ground on the SJB gets me ~700 ohms. Not good news! Now to test the lights and see if I can find a corroded wire somewhere.

 

Fully fixed! The license plate bulb connector had been replaced at some point and it was not done very well... The ends were rubbing on each intermittently and heating up. Thank you so much for your help! Cleaning the SJB (even if it wasn't the main problem) was a good thing and it made the lights much brighter.

 

Good stuff

Thank for the update and THE FIX