micky wrote:

Well, at the beginning of the the Toyota Electrical manual, are two
pages with 36 electrical symbols and what they mean, and for this
circuit, the diagram uses a symbol which it says at the start of the
manual represents a thermistor, but it's not the symbol everyone else
uses.

Plus they use the same symbol** for the intake air temp sensor, the
engine coolant sensor, the Air Conditioning room temp sensor, and the
AC ambient temp sensor. . Might those really be thermistors too?

**a zigzag resistor symbol inside a circle that has been elongated in
one direction, like a model train track cricle with extra straight
track in opposite sides. .

I haven't taken apart the door yet, so I don't know what is actually
there.

My plan was to add to the passenger door-unlock output of the
door/burglar alarm Eloectronic Control Unit a wire to a relay, which
relay would unlock the trunk. What's connected to that output now is
the door lock/unlock motor (solenoid?) and this "thermistor", in
series, according to the diagram, and I wanted to understand what is
there now and what it does, before I start fiddling with the circuit.
The other end of the door lock circuit goes to ground and so will the
other end of my relay circuit.

I'm reticent because with the previous car and the previous alarm,
that I installed from scratch, everything was fine, except to open
the trunk, I had to hold down the third button for several seconds.
Because my turnk lid didn't move when unlatched, I thought it would
work better for me if I connected the trunk relay to the both-door
unlock output of the alarm I installed, in parallel with the
door-unlock relay. . However that appeared to screw everything up,
so that many of the alarm functions no longer worked. I must have put
too much drain on that output, even though I just doubled the drain
(two standard automotive relays instead of one) I shoulld I guess
have put the second relay in series with the first one, so that when
it powered the door-unlocks, it also powered the trunk relay.

I'm trying not to make the same sort of mistake here.


A properly chosen thermistor will heat up and limit current if the
motor is stalled. It will also provide more a bit more current on cold
days, when you need more torque because of stiff grease in the
mechanism.

Car companies are not in the electronics business, so they use what
they feel that mechanics can understand.


--
You can't have a sense of humor, if you have no sense.