In alt.home.repair, on Fri, 21 May 2021 22:19:52 -0400, micky
wrote:


This is ASSUMING it is not STILL just an issue of not having the
instrument panel dimmer adjusted properly which was my FIRST
suggestion months ago.

I don't remember ignoring that line but I've been busy lately and
haven't caught readers here up on a lot of projects in progresss. I
hope to do that soon.

Anyhow, the dimmer didn't solve my problem (even though it seemed to
solve the opposite problem for people asking questions on the web.

And there is no detent on this dimmer.

BUT WHAT IS REALLY INTERESTING I LEARNED LAST NIGHT. I went out at 2AM
to check the car, even though I was sleepy and didn't really want to,
because if I didn't, I'd have to have waited until the next night.

So... in the dark, when the taillight relay is bypassed so that the dash
lights** are on even in the daytime, and the Clock lights are on
(because it's dark) the dimmer controls the brightness of all the
lights, every one***

BUT, AND GET THIS BUT, when I remove the jumper wire**** so that the the
dash lights** are not lit, then the dimmer control has NO EFFECT on the
Clock lights. The lights are at full brightness.


So in a way the Clock lights are independant of the Dash lights, but
otoh, they're simultaneously controlled by the same dimmer. That took
some work on Toyota's part.


The dimmer wiring isn't shown in the wiring manual -- I don't think the
dimmer is shown at all and certainly not individual wires -- but now
that the speedometer is out and its back off, I can see a little box
1/2" cube, on the surface of the circuit board, directly behind the
dimmer knob. It has a short connector, 1" wires, to the ciruit board
with yellow, red, blue, and black wires. I think it might only need 3
wires if Toyota had wired all the lights the same and the fourth might
be related to the Clock.

But I don't know which wire is the fourth, and if I did I wouldn't know
whether to cut it or to ground it, or what. The circuitry is too
confusing to me, since sometimes the dimmer has an effect and sometimes
it doesn't. And it's too close to other wiring it could affect. OTOH,
if nothing else works I might come back and fool around here.


It is so complicated, and Toyota went to a lot of trouble to make it
work this way, when if they'd done nothing and wired the Clock lights
the same as the other panel lights, it would have made more sense IMO,
not just for me but for anyone. And it would have enabled me to easily
hotwire them.

I don't miss not having lights on the other dash lights during the day
time, because everything is visible anyhow. The instruments are moving
needles, or there are buttons that can't be missed. As to the shift
indicator, I rarely look at that. I know where I put the shifter. As to
the glove box light, I think it should be illuminated in the day time
too, but it's been 30 years since I hunted for something in the glove
box. It's only the clock and the mpg/etc. that I want to see, and
because they are the only LCD indicators in the car, these are the ones
I can't read.



**Speedo, radio, AC, and seat heater buttons, console gear indicator
light, and glovebox light.

Still working on this but a temporary report.

Took out the speedometer, but even though there are 64 wires spread over
2 connectors (40 and 24) none of the wires were the right color W-G.

So I had to take out the Clock cluster again.

This time it was a little easier because with the speedometer out, I
could get my hand in and behind the clock. Couldn't push more than a
bit, but enough to stick a screwdriver in from the top.

Took the clock out, again, because can't see the wiring otherwise.

20 wires and one is the right one, ILL-, W-G, and I will cut it today
and see what happens, and try grounding the clock end, maybe through a
resistor, and see what happens. Except it will be 93 degrees so may
wait until tomorrow.


Last night I came home at dark with no speedometer and no clock and was
quite surprised that NONE OF THE DASH/PANEL LIGHTS WERE ON!!! The
outside lights worked, inclduing the turn signals, but the 12v that is
supposed to be on whenever the engine is running must not have been.



I almost know the wiring diagram by heart now and I find that another
curiosity. Taking out the speedo and the clock shoudbn't have caused
this but it did. I should have checked the wipers, washer, seat
heaters, etc. which are on the same relay. A relay that should have
been closed when the ignition is on (even if the car isn't running.)
I'll do that tonight.