jordanirvin

Hello all,

1992 3.0L V6 VZE AT 4wd.

My greenish background lights are not working. Everything else in the equipment cluster works--A/T temp, oil light, gas gauge, temp gauge, turn signals, hazards, bright light indicator, speedometer, etc.
However, the background lights are completely off no matter what position the dimmer rheostat position is. This is obviously when the lights are on. All the fuses are good.
The previous owner put in a new stereo and speakers, and tapped into the cluster of wires (green, white with a black stripe and red with a black stripe) going to the dimmer. It also appears that someone took a screwdriver to open and see the guts of the connector at the dimmer.
When I test with my multimeter, I get a weak signal in the electrical connector with the lights off, and off the scale when the lights are on.
I took the dash apart, and unplugged each connector going to the equipment cluster of the dash, and one by one, a group of lights went off (eg the oil light, or the flashers), and then came back on when I reconnected. However, the background lights still do not work.
Also, perhaps related, or maybe a separate issue, the indicator lights for P, R, N, D, D2, etc on the automatic transmission gear shift do not light up.

Someone on here must have encountered this problem and a fix before.
My knowledge of electricity is limited, so I won't mind if you explain this to me like I'm 6 years old. What should I be looking for--it seems like all the connections are solid, and I can't find a broken wire anywhere. All the other electronics from the stereo head unit, speakers, lighter, dome light etc work fine.

It is all disassembled now, and will probably remain so until I can get this fixed.

nv4runner

Have you tried swapping known to be working bulbs into places that are not working? Could be as easy as a trip to your local pick 'n pull to pop out the cluster and get a few bulbs from various other Toyotas.

Gamefreakgc

x2, easiest check at this point. Probably just a burnt out bulb, they don't last forever.

Also, if turning your rheostat doesn't adjust your lighting then it's most likely bad. Mine was broken when I got it, only stayed on dim. Once again, pick and pull did the trick and it works like new again.

jordanirvin

I've replaced the bulbs (194B), even though the old bulbs looked good. The bulbs aren't the issue.

I think the problem has to be the relay on the rheostat. With the multimeter, I believe that there is power coming to the dimmer, and this responds to me turning on the headlights. However, when I trace this to the connector on the dash and test the pins there, it doesn't appear that I have power.
The fuse that powers the tail lights work. I blew this in the process of messing with the relay. I replaced the fuse, and the the tail lights now work, but the dash lights still do not.
Does anyone know the part number for the dimmer relay? The only code I see on it is 241-0B18. I have googled this with no success.

Perhaps related, my automatic gear shift does not light up either. There is a very small bulb there. Does anyone know the bulb number for this? As a separate post, I'll might detail taking this all apart, cleaning out probably a spilled can of coke. I'll title this how I know my gear shift is cleaner than yours.

scope103

Your problem is in the "rheostat," 84119-20082, not the "dimmer." What Toyota calls the dimmer is the high-beam switch.

There is no relay in the rheostat; it's just a rheostat. The lamp side connects to 12v through the taillight fuse, the rheostat grounds the lamps. So if your rheostat is open you should find 12v at the rheostat (and grounding that should turn on the combination meter lamps).

You can test the rheostat using the procedure on page be-42 http://personal.utulsa.edu/~nathan-b.../6combinat.pdf

(nv4runner: would you really use junkyard bulbs in the combination meter? How much would that save you, a dollar?)

jordanirvin

Scope, thanks for the answers, part number, and link to a diagnostic test. Apparently the rheostat is a $60-$90 part.
I won't be able to get to a junk yard until this weekend at a minimum, and maybe longer. Is it possible to bypass the rheostat all together, meaning the lights would be on all the time?

p42 here: http://personal.utulsa.edu/~nathan-b.../6combinat.pdf
shows the rheostat has three connections (1 white/black stripe positive, to light; 2 red, negative; 3 green, from light).

Using the wires only, how would I by pass the rheostat so the lights are constantly on? Shouldn't this help me diagnose if the rheostat itself is bad or if there is a problem in the integration relay or somewhere else I haven't looked?

scope103

My EWD shows pin 2 to ground (negative) through white/black, pin 1 to +12v through green, and pin 3 to the ground-side of the lamps through white/green. But you don't have white/green, and you do have red. And your pinouts (if you've traced them correctly) are all different.

So you could try removing the rheostat and connecting your red (which may be the white/green I see) to ground (white/black); that should leave the lamps on full when the taillight relay is closed.

But if it were me, I would a) test the rheostat, and b) test the wiring. Use your voltmeter to see if you have 12v on red with taillights on. If you don't, there's a broken wire somewhere. If you do, use a test light to connect red to ground; you should have 1/2 power dash lights. (Why a test light? Because if the 12v you're measuring is not through the dash lamps but instead is direct connection to 12v, if you just short red to ground by touching it to the frame you'll weld it there, until a fuse blows.)

Good luck!

Nervo19

You didn't say if you checked if your rear lights are working. In every car since about 1968 if the rear lights aren't working the dash lights go out too as a safety warning. When mine went out it turned out to be an improperly grounded aftermarket stereo. It was causing the fuse to blow. I finally cut the ground wire on the stereo harness and grounded it directly to bare metal. The stereo is not on the same fuse as the dash/lights either. Another cause for rear light trouble is the tow harness. They wear out. Come back when you find the solution so we can add yours to our body of knowledge.

Edit: Akk. You DID say all the fuses are good. The dimmer rheostat is sometimes bad and you can clip the wires and take it out of the equation. The lights wouldn't be on all the time, they would just be the brightest they can possibly be when your headlights are turned on.

jordanirvin

Nervo19,

The tail lights/brake lights work. I'm not sure about the license plate lights, and other than the mulimeter, I'm not going to have a good way to test the tow harness.

I'm going to work tonight on clipping the wires and to take the rheostat out of the equation. This seems like the most straight-forward way to get an answer. If this doesn't work, then it means I have a short somewhere behind the heater vents or something like that, which is going to be very problematic.

If this works, then I'll save myself the trouble of going to the junkyard and hoping a part there isn't as old and dead as mine.

Gamefreakgc

Problem solved for $25 (I paid $7 for mine at pick and pull):

http://www.ebay.com/itm/Toyota-4Runner-Surf-Hilux-Pickup-Truck-dash-light-DIMMER-CONTROL-SWITCH-89-95-94-/370914038799?pt=Motors_Car_Truck_Parts_Accessories&hash=item565c33140f&vxp=mtr

jordanirvin

I'm so mad I could almost scream!

I tried to bypass the rheostat tonight with a simple rocker switch, and ended up blowing the tail light fuse 9 times. If this isn't the definition of insanity, I don't know what is. No matter what combination of wires I tried, when I flipped on the headlights, I blew the fuse immediately.

The previous owner installed an aftermarket stereo headunit and speakers, which works fine. However, is it possible in that process that he disconnected a wire (maybe a ground) that would explain my problem? Every other light/gauge in the truck works (with the exception of the auto trans shifter light), so I don't have any suspects.

Perhaps someone can explain, in the most basic terms, how to bypass the rheostat so my background dash lights are controlled by a rocker switch.

scope103

No one says you have to listen to me, but at least you're only out a handful (well, two handfuls) of fuses.

Why don't you try to figure out where the wires are going? Since you have non-standard coloring, either the EWD I have doesn't apply to your vehicle, or yours is ... different. This is a simple multimeter job. You've determined (sorta) that one of the wires is 12v, and one of them is ground, but you don't know which ones. (It also seems that none of your wires goes to the dash lamps as it should.)

jordanirvin

Scope103,
I've tried to follow what you've been saying. I was blowing all those fuses trying to bypass the rheostat or wire a rocker switch in place.

I'd love to figure out where the rheostat gets its power from, and where that wiring then goes. As far as I can tell, after it leaves the rheostat, it works its way behind the heater, then plugs into a junction box (?) inside the dash near the A pillar on the driver's side. A bigger bundle of wires leaves there and heads to the dash. However, this is all hidden in flex tubing, tape, and heater ducting. I don't have a worthwhile and readable wiring map with physical locations inside the truck. Can you tell me which connection pins I should be testing in the dash? There are connectors with 12, 10, 8, and 12 pins--See the picture below. I believe the background lights go into the left most connector (when looking from the driver's seat)--this is above the 906 in the pciture, but I can't really be sure. If I'm able to trace this correctly, the red and green wires by my thumb are coming and going to the rheostat.

I saw in another post that an aftermarket stereo could be sending too much power to the rheostat (and has probably cooked this). This might explain why it blow the fuse if I try to bypass the rheostat. I'm going to pull the fuse for the radio tonight and then try my rocker switch bypass again.

scope103

According to this page http://personal.utulsa.edu/~nathan-b.../6combinat.pdf pins D1 and D2 power the dash lights. The diagram indicates that D2 is connected to the TAIL fuse, but I'm guessing they mean TAIL relay (12v with taillights on). Also, the diodes in the drawing suggest they have D1 and D2 reversed, with the TAIL fuse actually connected to D1 and rheostat to D2.

How do you tell? Easy; put your voltmeter on D1 (or D2, try them both) and ground (with the connector disconnected) and turn on the tail lights. Do you get 12v? If so, put your ohmmeter from the other wire (D2?) to the same color wire at your rheostat. Continuity? Once you've sorted out which wire at the combination meter is the 12v from the TAIL relay, and which is the "other" to the rheostat, you'll plug the connector back in and ground the "rheostat" wire through a test light. (Why?)

Once you've got that squared away, I'll bet the wire colors at the rheostat are the same by function: for instance, the red/white wire may be 12v from the TAIL relay, and the green/white wire may be the ground side of the dash lamps (leaving white/black as ground). You can check them at the rheostat the same way.

Finally: if the wiring is not completely bunged up (with someone having switched the color of the wiring inside a bundle, for instance), then you just need to connect the ground-side dash lamp wire (green/white?) to ground (white/black?) through a rheostat.