Today I put in another dashlight rheostat dimmer dial in my 88 v6 Runner and this did not fix the problem. I still have dash lights at one intensity and no control on the rheo dial. The dial is good and the ground at the connector is good, but there seems to be no power comming out of the dash connector. I quess the question is then where does the power originate for this dial if all the current is shared with all the dash lights?

 

I don't know if this will help any, but we had a customer come in from out of state that was having all kind of electical issues. It turnes out she had a Cd changer, amp, and new head unit installed. Who ever did the install had hooked it up to the rheostat for some reason. It was creating all kinds of wierd problems.

 

That isn,t it. I put in my radio and just plugged into stock harness no big power amp or anything. This just happened about 2 weeks ago. The dial dimmer rheo. did work and change the light intensity up until then. I have not done any creative electrical work, and like I said it has worked since I owned this vehicle so the problem is new.

Thanks for any input.

 

Does the RADIO that you installed have a dimer circuit?

The Toyota Rheostat works BACKWARDS to normal convention...

Most cars are wired
+12v -- rheostat -- light bulb -- ground
Toyota is wired
+12v -- light bulb -- rheostat -- ground

If an aftermarket radio is used - they often "cheat" and tie the radio's dimmer light to ground...

Thus ALL your instrument lights run through the radio's illumination ground and not the rhestat...

Be prepared for futher eletrical wonkyness if the wires and circuti board in the radio cant handle the current draw....

 

My radio may have a dimmer circuit. I will have to look in the manual. In fact my radio has all kinds of crap that I am unaware of. I may of changed the background or something or hit a button while driving. The radio has been since Nov.06 and this is the first of the "issue" of no dial rheo. control.

12v bulb rheostat ground. Is that possibly why I show no current at the terminal? Dash bulbs light but current does not get to the rheo.
I thoght for sure the curent would hit the rheo then go on to its destination.

 

Exactly - when an aftermarke stero is installed that has a dimmer circuit - it typically wires the radio illiminiton ground to the radio chassis ground.

So when you connect it to a Toyota harness, the dash lights ground via the radio and not the rheostadt like it s supposed to

b

 

So I looked in my radio book this morn. and I do have a dimmer feature. I scrolled through the buttons and turned off the autoDIM feature. This however had no effect on the rheo dial problem. I may have pushed a button along the way to change the setting but why would this problem be happening now and not when I installed it months ago? Could the ground in the stereo be bad? If I unplugged the stereo should this "fix" the problem so the rheo dial would work again?

 

You need to DISCONNECT the illumination 12v input to the aftermarket radio.
You can then jumper the Radio's 12v illumination to the ign power line.

The radio will NO LONGER DIM.

I have no idea if any damage was done to the harness...

 

I will try that maybe this week. But should I not be able to check it quickly by just unplugging the radio completly, or if damage has been done to the harness the problem is now there with or without the radio in.

 

Ok I blew off some things to get this figured out today. First took out new stereo put in old cassette player and all worked fine. Nice to know my original stereo and all wiring was ok. Spliced in wires as descibed above and put it all back together and all works great dimmer dial and all.

Thanks alot for the help this was my first posting so nice to know it worked. This would of driven me crazy. This does not explain why it worked for 9months then started this that is baffeling to me. It is fixed and I am happy.

 

maybe when you switched the radio's illuminatoon color the RADIO'S circuti changed the illimination resistance to ground?

Anyway - glad to see you got it sorted.

You COULD make a voltage follower circuit or cut the illumination ground inside the radio....

 

Now that it is over and done I was wondering if I shouldn't of tried disconnecting the car battery then hooking it back up and maybe that would of re-set the radio to the original setting that worked?? Hmmm.