In alt.home.repair, on Fri, 21 May 2021 05:43:40 +1000, "Rod Speed"
wrote:



"micky" wrote in message
.. .

Addressed especially to Clare and to anyone who thinks he's as smart as
Clare is.

Here is the wiring diagram for this car's Clock,
https://www.dropbox.com/s/xoj71v8wiw...Clock.odg?dl=0
......

BTW, if I use a dark-colored multi-layer rag to cover the light sensor
in the dashboard, I will trick the headlights into going on in the day
time. It takes 4 or 5 seconds for them to go on, and then about the
same for them to go off when I remove the rag. But doing this doesn't
make the Clock lights go on. But night time does make the clock lights
go on. What makes the car think it's night if covering the light
sensor didn't do that? WHAT ELSE COULD THERE BE?


So I looked in detail at the Clock. It's supplied by 5, count 'em,
five, fuses. Pins 7, 15, 16, 17, 22

7 comes from the IGN fuse, 12v when engine running
15 comes from the Panel fuse, 12v when it's dark out
16 comes from the Gauge1 fuse, 12v when ignition sw. is ON
17 comes from the ECU ACC fuse, 12v when key in ACC or ON
22 comes from the Dome fuse, always 12v,

All the pins are described next. Pin 6 seems hard to understand.

Pin 6. TAU terminal on the clock. Goes to Injector No. 1 WHY? Why
does it have input from the Injector. To calculate MPG, really? Even
though it has input on 5 labeled Fuel and on 12 labeled Speed. So why?
Certainly not to tell the clock when it's dark out.

Below, I'm assuming what some of the pins do. For example, if it's
called Fuel and comes from tghe speedo cluster, I asssume it's coming
from the fuel gauge and has to do with computing MPG.


Label Color Conn. Function
1 GND1 W-B
2 TH- B-W IG6 AC ambient temp sensor (near front bumper)
3 TH+ G-R IG6 return from 2
4 SW 1 R Steering wheel display-control, and on to ground
5 FUEL LG-R to speedo cluster, fuel gauge, used for mpg display
6 TAU L IM2 to Injector No. 1 WHY? Why does it have input
from the Injector. For MPG? but it has input from 5-Fuel and
12-Speed.
7 TAUB B-R IM2 return from Injector No. 1 and also to IGN FUSE, 12v
when engine running
8 TBD L-B airbag sensor, 1
9 TX-1 W-B **but doesn't appy to my car
10 TX-2 W-B same as 1 for some reason
11 PBEW L-R airbag sensor, 2
12 SPD V-W to speedometer, used I'm sure for mpg display
13 DATA G-Y IK1 WHY? to TAM A11(A) A/C Control Assembly. So does
TAM mean Temperature AMbient? I guess so, since the AC page shows just
this part of the clock including pins 2 and 3 (the ambient temperature
sensor), and since the instrument 3 in the list at the top is the
outdoor temperature.
14 P-AB V airbag sensor, 3
15 TAIL G to Panel FUSE, but light goes on at night even when
Panel fuse is missing, and doesn't go on in day-time, even when
Taillight relay is bypassed and Panel Fuse is energized.
16 IG R-L to Gauge1 FUSE, 12v when ign. sw. ON, powers the
pass. seat belt warning light and much other stuff, only have 2006
list.)
17 ACC Gr to ECU ACC FUSE, 12v when key in ACC or ON (also
headlights, fog light, speedo meter, power mirror, AUTO LIGHT CONTROL)
18 ILL- W-G to speedo cluster (combination meter)
19 TAMO LG-R to skid control ECU. What does this have to do with
any of the 3 gauges in the clock?
22 B+ R from Dome FUSE, always 12v, needed to keep clock
running all the time (also dome light, fob receiver, garage door
opener)


But does any of this show how the lights in the Clock are on at night
and not on during the day?


(Part of the reason it's taken so long to ask this question is that some
testing can only be done at night and some only int

Its certain that the problem is the programming, not the simple
electrical connections. The evidence for that is the delay you
see when covering and uncovering the photocell. That proves
that it isnt simple electrical connections driving what you see.

Even so, regardless of what the programming in the body ECU or elsewhere
is, where the wires go into the Clock, there has to be something at
night that provides power to those lights, or in the daytime, a signal
that tells the Clock not to light up.

I'm ready to rewire the car to make up for that.

In the first case, if I could figure out*** what pin provides the power
for the light during the night, I could hot wire** it to provide the
same power during the day.

In the second case, if I could figure out which pin the signal comes to
the Clock to say don't light up, I could cut that wire. At least until
I saw what else that disabled. It might be worth it, it might not.


**That's what I tried to do in the first place. I removed the Panel
fuse but ran a jumper from the "On-when-runing power to the Seat Heater
switch" to the Seat-heater-light. Now all those dash lights in parallel
with the seat heater light are on whenever he car is running, not just
at night.

I want to do something similar for the Clock, but... Pin 18 goes to
terminal Ill-, which stand for Illumination, but it's negative. I guess
the possitive is one of those fuses.

Hmm going back to the speedo cluster would make sense if there was a
dimmer control on the speedo, and in some of the toyotanation posts
about dashlight, they had success by twisting the dimmer knob past the
detent. But those cars were a year or two newer, and I don't have a
detent. If I twist any harder, I'll break it.

Still, maybe if I "hot"-wire Ill-, pin 18, that is, not making it bot
but grounding it, maybe that will bypass something in the speedo part of
the dash board. The wire is W-G and goes to the combinaton meter,
their word for the speedo cluster. There are in the wiring manual 160
instances of the word "combination". [-(

***I tried taking the Clock apart, but it was just a circuit board with
a chip and a few other parts.