Same new-used car as in the other thread, a 2005 Toyota Solara.

Question about possible reverse voltage problem into an electronic
control module. Is there any chance that trying to put 12 volts into
what at other times is a 12 volt output can hurt anything? ***.

Car has a mechanical trunk release, plus the remote fob opens the trunk,
but it only works when the car is not running or maybe when the key is
not in the ignition.

But there is no keyhole for the trunk and if the fob breaks (as it did
for my prior car, a 2000 Toyota, same model) the only way into the trunk
will be the lever on the floor near the door in front of the driver's
seat. The problem with that is that I have to keep that locked, or
when the convertible top is down, someone can climb over the door or
crawl over the trunk and then open the trunk and take everything in it,
including my tools etc.

***So I want to install an electric release with a button on the dash
that works when the car is running, like many cars have (especially
convertibles whose designers were paying attention). I can't manage to
buy the shop manual except for the Elecric Wiring manual, and there is a
wire, Wire T, from the Body Control Module processor that goes back to
the trunk and powers the trunk release. I can run a wire from a hot
location to a push-button switch in the dash and from there to Wire T.

When the fob energizes Wire T, it won't hurt the switch, which is open
and not being pushed anyhow.

But what happens in the other situation, when the button is pushed and
12V+ heads to Wire T and part goes to the trunk and part goes to the
output of the Body Control Module? Is there any chance that trying to
put 12 volts into an output can hurt anything? I'm guessing it's at 0
volts when the fob is not being used.

On 10/5/2017 2:06 PM, micky wrote:
Same new-used car as in the other thread, a 2005 Toyota Solara.

Question about possible reverse voltage problem into an electronic
control module. Is there any chance that trying to put 12 volts into
what at other times is a 12 volt output can hurt anything? ***.

Car has a mechanical trunk release, plus the remote fob opens the trunk,
but it only works when the car is not running or maybe when the key is
not in the ignition.

But there is no keyhole for the trunk and if the fob breaks (as it did
for my prior car, a 2000 Toyota, same model) the only way into the trunk
will be the lever on the floor near the door in front of the driver's
seat. The problem with that is that I have to keep that locked, or
when the convertible top is down, someone can climb over the door or
crawl over the trunk and then open the trunk and take everything in it,
including my tools etc.

***So I want to install an electric release with a button on the dash
that works when the car is running, like many cars have (especially
convertibles whose designers were paying attention). I can't manage to
buy the shop manual except for the Elecric Wiring manual, and there is a
wire, Wire T, from the Body Control Module processor that goes back to
the trunk and powers the trunk release. I can run a wire from a hot
location to a push-button switch in the dash and from there to Wire T.

When the fob energizes Wire T, it won't hurt the switch, which is open
and not being pushed anyhow.

But what happens in the other situation, when the button is pushed and
12V+ heads to Wire T and part goes to the trunk and part goes to the
output of the Body Control Module? Is there any chance that trying to
put 12 volts into an output can hurt anything? I'm guessing it's at 0
volts when the fob is not being used.

Guessing is how you break things.
What is the trunk release?

If it's a solenoid CONNECTED DIRECTLY TO THE T-WIRE WITH THE OTHER
END OF THE SOLENOID AT GROUND AND THE T-WIRE GOES TO +12 WHEN
THE RELEASE IS ACTIVATED (MEASURE IT, DON'T ASSUME) that releases the
latch, I'd put a spdt pushbutton
that powers the solenoid only when pushed and hooks it to the control
signal when it isn't pushed.

If there's a control module in the back that sits between the T-wire
and the solenoid, you're gonna need a lot more info.

In sci.electronics.repair, on Thu, 05 Oct 2017 20:34:47 -0700, mike
wrote:

On 10/5/2017 2:06 PM, micky wrote:
Same new-used car as in the other thread, a 2005 Toyota Solara.

Question about possible reverse voltage problem into an electronic
control module. Is there any chance that trying to put 12 volts into
what at other times is a 12 volt output can hurt anything? ***.

Car has a mechanical trunk release, plus the remote fob opens the trunk,
but it only works when the car is not running or maybe when the key is
not in the ignition.

But there is no keyhole for the trunk and if the fob breaks (as it did
for my prior car, a 2000 Toyota, same model) the only way into the trunk
will be the lever on the floor near the door in front of the driver's
seat. The problem with that is that I have to keep that locked, or
when the convertible top is down, someone can climb over the door or
crawl over the trunk and then open the trunk and take everything in it,
including my tools etc.

***So I want to install an electric release with a button on the dash
that works when the car is running, like many cars have (especially
convertibles whose designers were paying attention). I can't manage to
buy the shop manual except for the Elecric Wiring manual, and there is a
wire, Wire T, from the Body Control Module processor that goes back to
the trunk and powers the trunk release. I can run a wire from a hot
location to a push-button switch in the dash and from there to Wire T.

When the fob energizes Wire T, it won't hurt the switch, which is open
and not being pushed anyhow.

But what happens in the other situation, when the button is pushed and
12V+ heads to Wire T and part goes to the trunk and part goes to the
output of the Body Control Module? Is there any chance that trying to
put 12 volts into an output can hurt anything? I'm guessing it's at 0
volts when the fob is not being used.

Guessing is how you break things.
What is the trunk release?

Yes, a solenoid.

If it's a solenoid CONNECTED DIRECTLY TO THE T-WIRE WITH THE OTHER
END OF THE SOLENOID AT GROUND AND THE T-WIRE GOES TO +12 WHEN
THE RELEASE IS ACTIVATED (MEASURE IT, DON'T ASSUME) that releases the
latch, I'd put a spdt pushbutton
that powers the solenoid only when pushed and hooks it to the control
signal when it isn't pushed.

I see your point. It's taken me a while to post back because I've been
looking for one big enough electrically. I don't know how much the
solenoid uses, and because everything, lots of things, go through that
control module, I can't judge from the fuse that supplies it. I found
an add-on trunk-release solenoid that it says uses 14 amps, but havent'
found an SPDT switch nearly that big that would look decent on the
dashboard.

Maybe I could put some diodes in parallel and use it to block the 12V
from the pushbutton from going to the control module.

Of course the module only sends current to the solenoid for a short
time. An add-on alarm I had one time allowed me to change the time from
iirc 1/10th of a second to 4/10ths of a second. Something like that.

I suppose the diodes woudl block the reverse current but the intended
current would blow out a set of 8 1-amp diodes if it sends out say 12
amps, even for a split second? I'd have to use 12 or 14 1-amp diodes
-- what a pile -- or find something bigger.

If there's a control module in the back that sits between the T-wire
and the solenoid, you're gonna need a lot more info.

No, the solenoid and control module are at opposite ends of the
T(runk)-wire

On 10/6/2017 9:36 PM, micky wrote:
In sci.electronics.repair, on Thu, 05 Oct 2017 20:34:47 -0700, mike
wrote:

On 10/5/2017 2:06 PM, micky wrote:
Same new-used car as in the other thread, a 2005 Toyota Solara.

Question about possible reverse voltage problem into an electronic
control module. Is there any chance that trying to put 12 volts into
what at other times is a 12 volt output can hurt anything? ***.

Car has a mechanical trunk release, plus the remote fob opens the trunk,
but it only works when the car is not running or maybe when the key is
not in the ignition.

But there is no keyhole for the trunk and if the fob breaks (as it did
for my prior car, a 2000 Toyota, same model) the only way into the trunk
will be the lever on the floor near the door in front of the driver's
seat. The problem with that is that I have to keep that locked, or
when the convertible top is down, someone can climb over the door or
crawl over the trunk and then open the trunk and take everything in it,
including my tools etc.

***So I want to install an electric release with a button on the dash
that works when the car is running, like many cars have (especially
convertibles whose designers were paying attention). I can't manage to
buy the shop manual except for the Elecric Wiring manual, and there is a
wire, Wire T, from the Body Control Module processor that goes back to
the trunk and powers the trunk release. I can run a wire from a hot
location to a push-button switch in the dash and from there to Wire T.

When the fob energizes Wire T, it won't hurt the switch, which is open
and not being pushed anyhow.

But what happens in the other situation, when the button is pushed and
12V+ heads to Wire T and part goes to the trunk and part goes to the
output of the Body Control Module? Is there any chance that trying to
put 12 volts into an output can hurt anything? I'm guessing it's at 0
volts when the fob is not being used.

Guessing is how you break things.
What is the trunk release?

Yes, a solenoid.

If it's a solenoid CONNECTED DIRECTLY TO THE T-WIRE WITH THE OTHER
END OF THE SOLENOID AT GROUND AND THE T-WIRE GOES TO +12 WHEN
THE RELEASE IS ACTIVATED (MEASURE IT, DON'T ASSUME) that releases the
latch, I'd put a spdt pushbutton
that powers the solenoid only when pushed and hooks it to the control
signal when it isn't pushed.

I see your point. It's taken me a while to post back because I've been
looking for one big enough electrically. I don't know how much the
solenoid uses, and because everything, lots of things, go through that
control module, I can't judge from the fuse that supplies it. I found
an add-on trunk-release solenoid that it says uses 14 amps, but havent'
found an SPDT switch nearly that big that would look decent on the
dashboard.

Measure the resistance of the solenoid and calculate the current.


Maybe I could put some diodes in parallel and use it to block the 12V
from the pushbutton from going to the control module.
Surely you can find a diode big enough to withstand the peak current.
Power would be negligible because of the short duration.
There are a couple of potential problems.
The inductive spike when the switch opens may put a lot of back
voltage on the series diode. Don't use a low voltage diode.
Or put a reverse diode across the solenoid to clamp the negative spike.
The other thing is whether the control module is smart and decides
to set an error condition when it can't sense the solenoid. Check that
before you go drilling holes in the dash.

Of course the module only sends current to the solenoid for a short
time. An add-on alarm I had one time allowed me to change the time from
iirc 1/10th of a second to 4/10ths of a second. Something like that.

I suppose the diodes woudl block the reverse current but the intended
current would blow out a set of 8 1-amp diodes if it sends out say 12
amps, even for a split second? I'd have to use 12 or 14 1-amp diodes
-- what a pile -- or find something bigger.

If there's a control module in the back that sits between the T-wire
and the solenoid, you're gonna need a lot more info.

No, the solenoid and control module are at opposite ends of the
T(runk)-wire

Famous last words. You're assuming the designer thinks like you.
VERIFY that there's not something else unknown at either end.

I once set a $2000 (1993 dollars) laptop on fire because I made
assumptions that the designers had used common sense in the design
of the battery charging system.

In sci.electronics.repair, on Sat, 07 Oct 2017 02:07:14 -0700, mike
wrote:

On 10/6/2017 9:36 PM, micky wrote:
In sci.electronics.repair, on Thu, 05 Oct 2017 20:34:47 -0700, mike
wrote:

On 10/5/2017 2:06 PM, micky wrote:
Same new-used car as in the other thread, a 2005 Toyota Solara.

Question about possible reverse voltage problem into an electronic
control module. Is there any chance that trying to put 12 volts into
what at other times is a 12 volt output can hurt anything? ***.

Car has a mechanical trunk release, plus the remote fob opens the trunk,
but it only works when the car is not running or maybe when the key is
not in the ignition.

But there is no keyhole for the trunk and if the fob breaks (as it did
for my prior car, a 2000 Toyota, same model) the only way into the trunk
will be the lever on the floor near the door in front of the driver's
seat. The problem with that is that I have to keep that locked, or
when the convertible top is down, someone can climb over the door or
crawl over the trunk and then open the trunk and take everything in it,
including my tools etc.

***So I want to install an electric release with a button on the dash
that works when the car is running, like many cars have (especially
convertibles whose designers were paying attention). I can't manage to
buy the shop manual except for the Elecric Wiring manual, and there is a
wire, Wire T, from the Body Control Module processor that goes back to
the trunk and powers the trunk release. I can run a wire from a hot
location to a push-button switch in the dash and from there to Wire T.

When the fob energizes Wire T, it won't hurt the switch, which is open
and not being pushed anyhow.

But what happens in the other situation, when the button is pushed and
12V+ heads to Wire T and part goes to the trunk and part goes to the
output of the Body Control Module? Is there any chance that trying to
put 12 volts into an output can hurt anything? I'm guessing it's at 0
volts when the fob is not being used.

Guessing is how you break things.
What is the trunk release?

Yes, a solenoid.

If it's a solenoid CONNECTED DIRECTLY TO THE T-WIRE WITH THE OTHER
END OF THE SOLENOID AT GROUND AND THE T-WIRE GOES TO +12 WHEN
THE RELEASE IS ACTIVATED (MEASURE IT, DON'T ASSUME) that releases the
latch, I'd put a spdt pushbutton
that powers the solenoid only when pushed and hooks it to the control
signal when it isn't pushed.

I see your point. It's taken me a while to post back because I've been
looking for one big enough electrically. I don't know how much the
solenoid uses, and because everything, lots of things, go through that
control module, I can't judge from the fuse that supplies it. I found
an add-on trunk-release solenoid that it says uses 14 amps, but havent'
found an SPDT switch nearly that big that would look decent on the
dashboard.

Measure the resistance of the solenoid and calculate the current.

Ah, of course. In my defense, I can't see the wires without taking the
interior or the trunk interior apart, and so I was hoping to take the
thing apart and put it back together the same day. With the previous
car, I took it apart and because of several problems doing what I
intended, didn't get around to reassembling it for 3 years, by which
time I forgot which screw went where. It is my biggest repair failure of
my life.

And toyota has it set up, just so one won't see a screw head, that to
get to one cover, he has to take off the next, and the next beyond that,
and the next.


Maybe I could put some diodes in parallel and use it to block the 12V
from the pushbutton from going to the control module.

Surely you can find a diode big enough to withstand the peak current.

Okay, good.

Oh, my gosh, the only real electronics store in Baltimore is closing:
http://www.baltimoresun.com/news/mar...011-story.html
"As sales dip, Towson electronics store pulls the plug". Oh, the
article is one year old this week.

"Paul Smith started to notice lagging sales in 2008 at Baynesville
Electronics, the store his grandparents first opened in their Joppa Road
home, near the intersection with Loch Raven Boulevard, in 1955.

Hoping that this was an anomaly rather than a trend, he hoped that the
business, which eventually expanded to 6,600 square feet, in a new
building at the same site, would right itself.

However, on Oct. 3, Smith, the president of the corporation that owns
the store and the 1-acre lot on which it stands, and his fellow owners,
announced that the store is closing for good.

While there is no official closing date, the once-popular purveyor of
electronic components and gadgets will lock its doors for the final time
after its inventory is sold, probably sometime in November, Smith
said.... We sell mainly component parts [used to repair computers and
other electronic devices], but people don't fix things anymore. We've
become a disposable society."

....."We made a conscience decision not to sell [products] online," [Yes,
it would have been nice if they'd had an online catalog, even if I had
to go there to buy things, but adding all their many items would have
been a big chore.] Smith said. "Our business is based on personal
customer service. We sell people actually what they are looking for. But
we just haven't had enough sales to pay for our inventory. Plus, there
are taxes and other rising costs to pay."

....."We had a grown man cry right here in front of me at the store," he
said. "He said he couldn't believe that we're closing. I had no idea
that we had that kind of impact on so many people. I heard that it was
announced by the local police at one of their briefings. We've had
hundreds of people calling to ask if it's true. To them, it's almost
like a death in the family."

...."From day one, after I moved here from Chicago [in 1993] I was told
that this is the place to go," the audio engineer from Timonium said.
"It's the only place to get some of this stuff, like grill speaker cloth
from the 60s. And some of the stuff I've gotten here, I know it's more
expensive than getting it on the Internet. But these guys talk to you,
give you tips, kind of like a local hardware store. Some of the things I
could get from the big-box stores, but I like the customer service here.
It's a lost art."

Rare are the times that customer Fred Gelhaus, 86, has gone to the store
and been unable to find what he wanted, he said — until his most recent
visit on Oct. 8.

"I've been coming here since it opened," he added.

...."They have service you can't beat," he said. "They are helpful,
knowledgeable and courteous. We'll miss them."

Cub Hill resident Bob Ernst, 74, a longtime buyer for Baynesville
Electronics, said that the Smith family always treated their employees
well.

"They treated me like one of their own," he said. "I never missed a
paycheck in 52 years."

Like workers in other businesses, however, employee health benefits were
taken away five years ago and no raises were given for even longer than
that, Ernst said.

Paul Smith's uncle, Richard Smith, 64, said that changes in the industry
began pecking away at profits in an incremental fashion.

"We went from tubes to transistors to integrated circuits to circuit
boards," he said, describing long lines of customers who would line up
inside the store to test radio and television tubes back in the store's
earlier days.

....Oddly enough, when local Radio Shack outlets closed, it also hurt
Baynesville's business, Ernst said.

"People thought that Radio Shack's closing was going to be good for us,"
he said. "And it was for a short time, but we lost a lot of business
referrals when they left."

Richard Smith said that the company's gross sales peaked at $1.7 million
in the late 1980s or early 1990s before falling to $800,000 last year.

"I used to ride my bike up here as a kid to get batteries," said Tom
Lortz, 61, who grew up in Loch Raven Village and now lives in Havre de
Grace, after purchasing headphone extension cables at the store on
Tuesday. "It's sad and depressing. Now I don't know where else to go to
get some of the things I'd get here. I feel bad for the employees, too.
I know most of them have been here a very long time.""

Their prices were very high, imo, but every 3 years or so, I used to buy
belts for my car's cassette player (they had a big selection) and I
bought a meter there once and lots of little things. Plus I liked
browsing. Darn.

Now I think there is no place to buy the diode but mail-order. In an
emergency, I suppose I could drive to Philadelphia. Maybe there's a
store there.

Power would be negligible because of the short duration.
There are a couple of potential problems.
The inductive spike when the switch opens may put a lot of back
voltage on the series diode. Don't use a low voltage diode.
Or put a reverse diode across the solenoid to clamp the negative spike.
The other thing is whether the control module is smart and decides
to set an error condition when it can't sense the solenoid. Check that
before you go drilling holes in the dash.

Good point!

Of course the module only sends current to the solenoid for a short
time. An add-on alarm I had one time allowed me to change the time from
iirc 1/10th of a second to 4/10ths of a second. Something like that.

I suppose the diodes woudl block the reverse current but the intended
current would blow out a set of 8 1-amp diodes if it sends out say 12
amps, even for a split second? I'd have to use 12 or 14 1-amp diodes
-- what a pile -- or find something bigger.

If there's a control module in the back that sits between the T-wire
and the solenoid, you're gonna need a lot more info.

No, the solenoid and control module are at opposite ends of the
T(runk)-wire

Famous last words. You're assuming the designer thinks like you.
VERIFY that there's not something else unknown at either end.

I've verified that already. I have the wiring manual. (I would buy the
other manuals but no one had them for sale. I'll look again in a few
weeks.)

I once set a $2000 (1993 dollars) laptop on fire because I made
assumptions that the designers had used common sense in the design
of the battery charging system.