rocker or toggle to bypass rheostat
10-17-2013, 12:01 PM
#1
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rocker or toggle to bypass rheostat
I have a dead rheostat that controls the background dash lights. I have confirmed the fuses, bulbs and wiring are good. I suspect a aftermarket stereo fried the rheostat, which is like a $75 part.
I'd like to bypass this with a $7 rocker switch starting at the connector on the back of the rheostat--see ELECTRICAL TYPE (#3) rheostat P14 or BE42 here: http://personal.utulsa.edu/~nathan-b.../6combinat.pdf .
However, every time I try this--no matter what combination of wires for supply/load/earth on the switch I connect to terminals 1, 2, 3, the tail light fuse blows. It does this if I don't use the switch for the ground, and instead go from terminal 2 to a frame bolt.
It does this even if I pull the fuse for the radio (and the radio then shuts off), so that should simplify my issues.
It's maddening that there are only three wires here and I can't figure this out.
I'd like to bypass this with a $7 rocker switch starting at the connector on the back of the rheostat--see ELECTRICAL TYPE (#3) rheostat P14 or BE42 here: http://personal.utulsa.edu/~nathan-b.../6combinat.pdf .
However, every time I try this--no matter what combination of wires for supply/load/earth on the switch I connect to terminals 1, 2, 3, the tail light fuse blows. It does this if I don't use the switch for the ground, and instead go from terminal 2 to a frame bolt.
It does this even if I pull the fuse for the radio (and the radio then shuts off), so that should simplify my issues.
It's maddening that there are only three wires here and I can't figure this out.
10-18-2013, 12:15 AM
#2
Remember if your plugging into the dash harness it will be opposite of the picture your looking at .
What year and model are you working on??
Why would you want to add another switch into the tail light circuit ??
Just how did you figure out the rheostat is causing your problems
Just what is your original problem ??
No dash lights ??
No tail lights??
No telling how you might have wired this up but your radio fuse powers the radio . If you plugged into the Toyota Harness your radio back light is powered through. your tail light/dash light fuse.
How that could have caused a rheostat to fail should be quite interesting
What year and model are you working on??
Why would you want to add another switch into the tail light circuit ??
Just how did you figure out the rheostat is causing your problems
Just what is your original problem ??
No dash lights ??
No tail lights??
No telling how you might have wired this up but your radio fuse powers the radio . If you plugged into the Toyota Harness your radio back light is powered through. your tail light/dash light fuse.
How that could have caused a rheostat to fail should be quite interesting
10-18-2013, 08:01 AM
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More details...sorry for leaving them out before.
1992 pickup dlx, 3.0L V6, 4WD, auto. I just bought this, and there are no lights behind the speedometer. My truck doesn't have a tach.
The background dash lights (green,two bulbs #194, replaced) don't come on ever. The gear shift light in the shifter also doesn't come on. Every other light and gauge works. The fuses are all good.
The rheostat controls the background instrument cluster lights. I have power going into the rheostat, which has 3 connections (power, to the lights, and ground). If I make a jumper here, I immediately blow the tail light fuse. I tried to replace this with a LED indicator rocker switch and get rid of the dimmer control feature. I can get the LED to light up, (I've got this grounded to the frame), but as soon as I flip the switch to light up the dash, I blow the 15A tail light fuse. This is the case if the stereo is connected via the hiring harness, and happens even if I pull the stereo fuse.
I read on other forums that an aftermarket stereo and wiring harness (also tied into the combination relay so that when the headlights are turned on, the interior lights dim) can draw too much power and fry the rheostat. This was on newer tacomas, but I thought that could be my problem, since my rheostat is non responsive, but has power. The previous owner put in a aftermarket stereo in my truck. I don't want to get a new rheostat (like $75, or a trip to the junk yard), install it, and then have my stereo cook it too.
I can not trace the wiring to find where the rheostat is grounded--maybe somewhere behind the heater duct up high near the A pillar. I've got my dash completely disassembled, the instrument cluster is out, the radio is out, the shifter cover is off, etc.
I have a wiring diagram from the chiltons manual, but that only shows the path, not the physical location inside the truck, so it is hard to inspect and see what wires could have a short.
1992 pickup dlx, 3.0L V6, 4WD, auto. I just bought this, and there are no lights behind the speedometer. My truck doesn't have a tach.
The background dash lights (green,two bulbs #194, replaced) don't come on ever. The gear shift light in the shifter also doesn't come on. Every other light and gauge works. The fuses are all good.
The rheostat controls the background instrument cluster lights. I have power going into the rheostat, which has 3 connections (power, to the lights, and ground). If I make a jumper here, I immediately blow the tail light fuse. I tried to replace this with a LED indicator rocker switch and get rid of the dimmer control feature. I can get the LED to light up, (I've got this grounded to the frame), but as soon as I flip the switch to light up the dash, I blow the 15A tail light fuse. This is the case if the stereo is connected via the hiring harness, and happens even if I pull the stereo fuse.
I read on other forums that an aftermarket stereo and wiring harness (also tied into the combination relay so that when the headlights are turned on, the interior lights dim) can draw too much power and fry the rheostat. This was on newer tacomas, but I thought that could be my problem, since my rheostat is non responsive, but has power. The previous owner put in a aftermarket stereo in my truck. I don't want to get a new rheostat (like $75, or a trip to the junk yard), install it, and then have my stereo cook it too.
I can not trace the wiring to find where the rheostat is grounded--maybe somewhere behind the heater duct up high near the A pillar. I've got my dash completely disassembled, the instrument cluster is out, the radio is out, the shifter cover is off, etc.
I have a wiring diagram from the chiltons manual, but that only shows the path, not the physical location inside the truck, so it is hard to inspect and see what wires could have a short.
10-19-2013, 12:14 AM
#4
First the fact that your gauge lights work tells me that your rheostat is just fine.
The lights that do not work might just have dirty sockets sometimes they can be corroded and it is not visible just looking. If other damage is not visible chewed or burnt wires.
Are you using a multimeter to check things.
Your ground is the white wire with black stripe it grounds on the left door post behind the plastic trim.
The rheostat completes the circuit to ground
I don`t have the EWD of the 92 pick up just the 4Runner but from looking at that it looks to be a solid state and not your normal manual rheostat Why it is so expensive.
If you plan to keep this truck it might be worthwhile to track down the EWD for it.
Without the proper EWD I would only be guessing from here.
The lights that do not work might just have dirty sockets sometimes they can be corroded and it is not visible just looking. If other damage is not visible chewed or burnt wires.
Are you using a multimeter to check things.
Your ground is the white wire with black stripe it grounds on the left door post behind the plastic trim.
The rheostat completes the circuit to ground
I don`t have the EWD of the 92 pick up just the 4Runner but from looking at that it looks to be a solid state and not your normal manual rheostat Why it is so expensive.
If you plan to keep this truck it might be worthwhile to track down the EWD for it.
Without the proper EWD I would only be guessing from here.
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