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2008
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50 Posts
Discussion Starter · #1 ·
I'm installing our cell phone amp underneath the pass seat in our 05 TB and need to find a good power source for it.

The passenger seat has the 8 way power and heated seats. There is a large harness of wires (approx 12) underneath the front of the seat. The large orange wire is HOT all the time, and I presume the large black wire is ground.

Does anybody know if any of the wires are HOT with the key in the on position only?

:thx
 

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Banned
2004 gmc
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26,181 Posts
Almost all functions like that in the trailvoy platform have constant power. They're woken up by a serial data bus signal, and put to sleep the same way when the ignition is turned off. This reduces the electrical load on the ignition switch and should have resulted in longer lifetime for the switch.

But alas, the switch design team fell on their faces and we're stuck with unreliable switches. :hissy:

Same thing for the radio, so there are adapters you can buy (see the sticky in the audio forum) to listen on the bus and wake up and power aftermarket head units.

That said, there ARE a few fuses in the rear fuse panel that are hot ONLY when the ignition switch is ON/ACCY/START. Use an add-a-fuse tap to steal power from those circuits, like rear fuse panel fuses 47 or 50. For RUN mode only, tap fuse 44, 48, or 51. For ACCY/RUN, choose fuse 29 or 33.

 

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2004 gmc
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26,181 Posts
Can you tell me where the rear fuse panel is and is it difficult to get at?
Ahhhh, the month is so young. :D But I don't recall EVER getting this classic question before the 5th or so. :laugh:

Congratulations on being *the guy* for July, 2009. :tiphat

Seriously, new owners come in here all the time and show evidence that they never cracked the Owner's Manual or showed curiosity in the vehicle they just bought. As an enthusiast and sort of car nut, I found the fuse blocks before I even bought the vehicle. So I have to poke a stick at folks who ask this question. Sorry. Sorry. It's my nature......



Ahhh, I can be constructive, though. In case you got a truck where the Owner's Manual was stolen by the previous owner (I never understood that syndrome either), we have PDFs under the Resources menu above.
 

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2008
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TFF.....I like being "the guy!" :bonk:

I have cracked the owners manual and read thru it. I recall seeing the diagram for the rear fuse block, but don't recall where it is. The dang owners manual on the TB is like 600 pages long!!! :duh:

The wife is back home and I found the rear fuse block. :duh: Do you think there's be any problems if I use the 4WD fuse? I checked and it's keyed power. I'd rather lose 4WD than wiper or other functions.

:thx
 

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Registered
2008
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50 Posts
No problem using the 4WD fuse.

Imagine how I felt after sitting down with the 6000 page SHOP manual for a couple of months learning the systems. :weird:
oui vei!!!!!

:thx for your help!!!

there's so many things I want to do to our TB and not enough $$$ to do it!!!!

No problem using the 4WD fuse.

Imagine how I felt after sitting down with the 6000 page SHOP manual for a couple of months learning the systems. :weird:
Is there a ground somewhere in the rear fuse box that I can use? I could ground off of the fuse (stick a wire on the neg side), but that's not the way I like to do things!
 

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2004 gmc
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26,181 Posts
I was working up a big fat sarcastic comeback, but the wind got knocked right out of my sails. :hissy: Sarcasticus Interruptus. ;)

Seriously, the fuse block is a collection of all hots. Grounds have no place in a fuse block, and I was about to post that. But I would have BEEN WRONG!

The fuse blocks actually do need grounds for a couple of reasons. In the rear, one reason is to include some grounds in the flat cable harness going to the BCM. In the front and rear, grounds are needed to connect to the low side of various relay control pins.

But they're not as easily accessible as on a fuse, since (unless I'm mistaken) there aren't neat little gadgets for relay sockets as there are for fuse sockets to easily add a signal tap. Wish there were.

Just drill a small hole and use a sheet metal screw to the floor if you're worried about the big fat seat bolts.
 

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Registered
2008
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50 Posts
Discussion Starter · #17 ·
Almost all functions like that in the trailvoy platform have constant power. They're woken up by a serial data bus signal, and put to sleep the same way when the ignition is turned off. This reduces the electrical load on the ignition switch and should have resulted in longer lifetime for the switch.

But alas, the switch design team fell on their faces and we're stuck with unreliable switches. :hissy:

Same thing for the radio, so there are adapters you can buy (see the sticky in the audio forum) to listen on the bus and wake up and power aftermarket head units.

That said, there ARE a few fuses in the rear fuse panel that are hot ONLY when the ignition switch is ON/ACCY/START. Use an add-a-fuse tap to steal power from those circuits, like rear fuse panel fuses 47 or 50. For RUN mode only, tap fuse 44, 48, or 51. For ACCY/RUN, choose fuse 29 or 33.

I had never used one of these gizmos. I ass/u/me d that I had to increase the amp fuse that I would put in this thingy.

Lo and behold it has two fuse slots (just like in the picture :suicide:)....one to put in the original fuse, and the other for what you are attempting to hook up.

Ahhhh soooo said the pollock from NC WI!!! :D

Fished a single power wire back to the fuse block...not too hard of a job.

As to the ground wire, I'm going to ground it on one of the big bolts holding down the pass front seat.

Project is not complete as I am waiting for my new inside glass mount antenna to arrive.

:thx and keep the comments coming!!!! LOL!! :thumbsup:
 

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2002 chevy trailblazer_lt
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846 Posts
What kind of booster are you putting in?

Oh, and do be careful when you put a socket on that ground, pushing past a very fat 12V wire on the way. Could lose your Megafuse that way. DAMHIK. (Don't ask me how I know. I was a noob once.)
I learned about the dangers of a socket wrench near a cable like that the hard way. :bonk::bonk:
 
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