v6phoenix

Ok, so I recently purchased a 93 Toyota pickup with a v6 and manual transmission, fixed most of the problems and saved this electrical one for almost last. First of all, when I bought the truck, there was no rheostat switch for dimming the dashlights. Instead, there was a red w/black stripe wire and a white wire w/black stripe hooked up to a toggle switch. There is also no radio in the truck.

So the weird problem is that when those two wires (red w/black and white w/black) are connected, the blower for the heater works fine, but I have no gauge cluster lights (speedo, rpm, gas meter, etc). When the wires are not connected, and the key is in the ignition and turned to "on" the dash lights work and the intensity is variable depending on how high the fan is turned on (fan on high, lights on high, fan on low, lights on low) BUT the fan no longer works (well it does a little but stays on low)

I looked at my haynes manual and i think it says for this truck the rheostat should have a red/white and green wire but I see no green wire under there that could have been snipped.

Here are some things i've checked:

1)fuses... over and over
2)tail light relay... good. tailights work fine and all other lights work fine
3)grounding the brown wire for the stereo (brown wire) and checking the voltage of the green wire with the tail lights turned on and rheostat wires connected, nothing. but with the rheostat wires disconnected and the key in on position i get voltage depending on how high the fan is set

4) looked for any independant wires which may have been snipped



I'm thinking it could be a ground for the fan blower? I've read alot of light related problems on these forums but never anything that was also related to the fan blower. this is whats so confusing to me

4Crawler

iTrader: (3)

Try a Factory Service Manual for the wiring information, there are on-line copies floating around if you search. The dimmer rheostat is wired into the ground leg of all the dimming dash lights. So it sounds like you are missing that ground connection and instead have a connection of the blower motor to ground that is getting used.

Hadmatt54

You should download the FSM wiring diagrams from the link on the 86-95 truck forum. There should be three wires attached to the reostat. There is a green, a green/white and a black/white. The green white is from the dash lights, the white/black is ground and the green is power from the 15 amp tail light fuse.
It sounds like there is a ground wire that is not connected and the lights or heater are finding a path to ground through another circuit.
All grounds in the truck are tied together, but there are ground points that are closer to the accessory. The front heater circuit (switch, resistor and blower) is grounded at point 1E which is under the left kick panel. The combination switch, gauge lights, reostat and the front R.H. parking light are also grounded at point 1E.
It looks like the PO had a ground problem and instead of fixing it properly he butchered the harness to get some things working or at least semi-working.
The the only red/black wire in that circuit is the power wire to the combination switch and it comes from the coil of the tailight relay, I don't know how yours is working, but it is supposed work like this. Power from battery, through fusible link to coil of the taillight relay, to combination (headlight) switch. Turn switch on to any position, coil circuit of taillight relay is completed to ground (white/black wire) and lights come on.
Find out where the red/black wire comes from, it looks like the toggle switch is taking the coil circuit directly to ground, but if that is what he did, then without these two wires connected together none of your lights should work!
A continuity test (ohms) of the brown wire to chasis ground should show that it is connected to ground already. It's the radio ground. Most of your grounds are white/black, but for whatever reason radio/stereo grounds and engine grounds are brown.
Also check the white/black at the reostat to a good chassis ground and the white/black from the heater switch to ground to see which (if either) is not a good ground connection. Then check them to one another.
Good Luck.