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So I've got a 2000 Ranger Super Cab and I'm experiencing the same door adjar light problem that seems to be common among Ranger owners where the switch is inside the door under the latch.
First thing I did to figure out which door it was was to start the car up and then open each door by it's self. The warning audio "DING" comes on when the driver's door is opened, but not when the passenger's is. So, that tells me it's the passenger door.
I tried the WD40 trick with no success so I then took the door apart. Pulled the switch out and found it was working with a test light. When the switch is pushed in it completes the circuit, so the switch was working fine.
While I had it unplugged I started up the car and the door light was still on. I then jumpered the two contacts on the plug together and started up the car again (of course with both doors closed to be safe). STILL the dash door light is on!
With that test done I figured I'd go one step further to be sure. I checked with a test light both contacts separately with one lead and then touched the door on a bolt that had no paint on it. BOTH contacts lighted up the test light, so I now know that both are grounded to ground.
That explains the problem because only one should be. I don't have a wiring diagram for this truck but I'm going to assume that the only one should be always tied to ground. One would pass through the switch when it's closed (meaning door is open) and then find it's way to ground via the other wire. When the switch is open (door closed) it can't find it's way to ground.
With all that figured out (I guess) I then drew up a simple circuit on paper that would explain all this to try to figure it all out. So far as I would figure the circuit may work like this...
When using either "map" light via it's switch they go directly to a ground and not through the switch. However, when the switch is in the off position (middle) the light's ground passes down to the door switch. I would guess that somewhere between the dome light and the door switch the problem probably is that the wire is shorted to ground, so it no longer needs the switch closed to complete the circuit.
That would also mean that the dash light can't be past the door switch. It must be on the same side of the short as the dome light and then the short to ground is somewhere between them and the door switch, and thus not needing the door switch closed to complete a pathway to ground. That makes sense but there are still a number of ways this circuit could be wired so I'm not sure unless I can see a schematic.
What complicates it more is I think these things have those little GEM (Generic Electronic Modules) somwhere in the circuit, which usualy consists of a relay or two. A stuck or shorted relay could also lead to the above problems.
If anybody has a wiring schematic for a 2000 Ranger's dome light/door swith/dash adjar light circuit I need to see it. I can figure out the problem from there but I really don't feel like pulling things apart looking for GEM modules that may or may not exist, so I'd rather read a schematic so I'm not shooting in the dark figuring the problem out.
Also, the dome light(s) have been removed to keep the light from staying on all the time. You know, I wonder if there might be a short in the dome light switch because I threw the bulbs back in to play around and it seemed real picky about it's movement. The slightest bump of the switch and the bulb(s) would go out.
The dome light might be shorting to ground causing the dash light to also come on, thinking the door switch is closed allowing a pathway to ground. That would also mean then that the dash light is before the dome light in the circuit, in that when the dome light grounds (if it is it's switch) the current completes it's pathway to ground, causing both the dash light and dome light to come on.
Still, I need a schematic or somebody's advice here who has had the same problem.
There's really not all that much to the circuitry. The driver's side door switch is grounded to the chassis underneath the driver's seat. The passenger side door switch is grounded to the passenger side fender apron underneath the hood. Both switch ground wires are black. The other wire for each switch runs directly to the GEM (pins 7 and 8, respectively).
When a door is open, the switch in the door is closed, sending a ground signal to the GEM. The GEM in turn (via pin #9) illuminates the "door ajar" lamp on the dash.
The main headlamp switch provides power to that part of the GEM which controls the "door ajar" functions.
I have the exact type of problem with my 2000 supercab 4 door. The interior and door ajar lights stay on and it only happens when I open the rear passenger door so I don't open it unless I have to. If I do, I pull the interior light bulbs and the door ajar light goes out eventually, same with the interior lights.
Ignorance makes you start over!
Yes, I have the 4 door Supercab 2000 Ranger and 3.0 V6/Automatic. I wouldn't think that the 3rd and 4th doors would have any kind of control, since the main doors have to be opened for them to be opened too, so that would be redundant to have them involved in the door adjar/dome circuit.
No, the dash dimmer/dome dial is not involved in the problem since the door adjar light is on. If it was that switch being in the "DOME ON" position that still wouldn't explain the door adjar light. Besides, I checked to make sure that switch was not clicked into the "DOME LIGHT" position.
What makes it more confusing is if I open the driver's door the door chime comes on, so it appears the circuit can sense either door being opened. Even though the circuit thinks the passenger door is open it can still recognize the driver door being opened separatley. For that reason I know the circuit is a little more involved than something basic. I was betting there must be at least a GEM control involved to sense that, so your info on the GEM module is helpful because I want to check that out. I'm also going to have to check the positive wire between the door switch and the dome light to see if the short to ground is there, but like I said I'm not sure if something is between them that can cause the problem, such as a GEM module.
Where exactly is the GEM for this circuit located, and are there any other GEMs involved? With what you've given me in info I may be able to pin down the problem. I went to school for HVAC and have extensive prior experience in electronics and troubleshooting as well, so all this is right up my alley. The main problem is that without a schematic I'd have to take everything apart to see if there are any hidden components and also to track down the routing of the wires. Electrical troubleshooting only goes so far if you don't know if there is or isn't other components between two test points.
Remove the radio and the GEM will be behind it on the left-hand side (ignore tap connector in pic):
As you can see, there are two good-size harness connectors attached to the GEM, so you have to be careful about the pin #s that I referenced in my earlier post. You can ascertain which connector I'm talking about by confirming the wire colors:
Hey, thanks a bunch to both of you for the info. Now I can start troubleshooting. First thing I'm doing is unplugging the other wire (not the black ground one) from the door switch and also at the GEM (assume it goes straight to the GEM?) and then checking if it's shorted to the frame. Like I said, both wires at the door switch are showing that they are shorted to ground, which only the black should be. Yes, I unplugged the door switch to check this. Hmmm....did I close the driver's door? Slight chance it can show that it's grounded with that open. Wouldn't think so, though, because I believe they are both on separate circuits because like I said if I open the driver's door the door chime sounds off, so that tells me they should be on separate circuits since that's the only way the truck would know the driver's door is also opened while it also thinks the passenger door is open all the time.
What also concerns me is I would figure that the power saver circuit or whatever it's called should be turning off the dome light after a certain amount of time, so maybe that's also bad, but will have to dig further into this circuit to figure things out. Always start at the source, which means the green/purple (think it's that color) door switch wire. More than likely it's simply got a short to ground in it, so first thing to do is unplug it at the GEM (if it goes right to there) and see if it's still shorted somewhere between the door switch and it. If it's not then more than likely the GEM is bad and is grounding that wire for some reason. Didn't even know where to look for this module so thanks again. I'll update you guys later today when I look at things and break out my multimeter.
Well, I printed out your message and picture and took the radio out. I couldn't get the radio to budge even with the proper tool so I took the two bolts out just above the heater controls and removed the radio along with the entire black dash cover, which was real easy to do that way.
The black box to the left side does not look the same as yours in the picture. Also, I could find no wire going to it that matched the color of the one coming from the passender door, which is I believe grey with a purple or red stripe, or you might call it light green or tan with a red or purple stripe. Probably is grey/red (or purple) though. Anyway, none of the wires going to that box matched it color wise. I did see a grey wire with a yellow stripe and a few other grey wires with like either a black stripe or none at all. Nothing that matched. My box has a grey connector roughly in the same spot but I don't think it has the black one to the left. Either way, I know it doesn't match your picture.
So, I figured I'd track that wire where it came in from the door by removing that plastic cover on the right side of the floor. It looks like the wire comes in, plugs into a large harness, and then routes up and over the glove box on the right side. I removed the glove door to see where it went and it looks like it goes up high into the dash and then over to the driver's side.
Either it changes color before it gets to that black box or it might plug in at the top and back side of the box, but I don't think so. It looks like all those wires go somewhere behind the dash's display and I'm not even sure if that wire is with them.
So, I'm stumped right now unless somebody has any information for me. I even went to an Auto Zone and looked up the schematics for a 2000 Ranger in the Haynes manual. There is NOTHING for the door circuits, let alone a GEM or where it might be located.
Like I said, either that grey/purple (or whatever) wire is grounded to the frame somewhere between the door and where ever it goes from there or I've got a bad GEM module somewhere, because when I unplug the door switch plug and test both pins on the plug both the black is grounded (which it should be) and so is that grey/purple wire, which it shouldn't so far as I know. I'm testing them both by using a conductivity meter which beeps by putting one lead on one of the plug pins and the other to the frame, testing each separetly.
I would figure it would either have to be a short in that wire or a bad GEM that is grounding it somehow, but until I know where this wire goes so that I can unplug it and test it there (with the door switch unplugged from it) to see if it's still showing that it's grounded I have no way to pursue this further.
ebay link above shows what your gem module looks like, assuming you have 2 wheel drive. You don't mention if it's 4 wheel or 2 wheel. Center dash behind radio. Don't even waste your time diagnosing. It's the world famous gem module fault if your switch is good
ASE certified tech
owner of roadside assistance co.
Yea, it's a 2 wheel drive automatic with 4 doors and 3.0 V6. Sounds like it's the GEM then, and from the looks of that ebay box and where it's located that must be what I found behind the radio. You're probably right in that it's a bad module. WOW! over $100 for that thing! I'm either going to live with it or go to a few local "self serve" junk yards and see how much they'd charge me if I took the box out myself, which is like a 5 minute job. I figure if it's over say $40 then I'll just live with it. On the other hand, I might just pull out my box and take the thing apart. I bet there is a bad relay in there that the ground input from the door driver's on the relay's coil that is used for the coil ground. Might be able to wack it go get it unstuck or solder (or unplug) it and put a new one in. Also, some relays can be taken apart to clean the contacts (which could also be bad...those would close when the coil is grounded (or open, depending on how they wired it) and dirty coil contacts can cause no current to flow. A little electrical cleaner might fix it.
Thanks for the info and the schematic as well guys. I'll keep you updated on this project.
Another clue that my wife noticed is that when the "door ajar" light is on, and you shut off the truck, you can't move the windows up or down like I could before. You have to turn the truck ignition back on to get them to work. (power windows) Things work fine when the "door ajar" light goes off. And yes, having a four door truck they are included in the door ajar/dome light circuit.
Ignorance makes you start over!
I had the exact same problem as you. I tested all the connections and switches for the passenger side and everything should have worked but didn't. I found this thread and took out the radio to access the GEM. As it's the passenger door that's playing up, it doesn't bother me if the switch doesn't work at all so I just cut the 'right door switch input' cable and problem solved. The dome light comes on and off with the driver's door, but just thinks the passenger door is always shut. Maybe not a complete solution, but works for me.
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