NEED HELP 12v ACC red for aftermarket radio

paul2005tb

Silver Supporter
#1
I'm a bit perplexed that my factory radio harness does not have red/ACC/12v in it, does anyone know if I need to find ACC somewhere in dash or if there is an ACC in the harness disguised by another color?
 

littleblazer

Gold Supporter
#2
I'm a bit perplexed that my factory radio harness does not have red/ACC/12v in it, does anyone know if I need to find ACC somewhere in dash or if there is an ACC in the harness disguised by another color?
Iirc there should be a heavier gauge wire, that is the one you want. But I believe that it may be always hot and there is a trigger for switching it on and off that switches with key on. It has been a while.
 
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paul2005tb

paul2005tb

Silver Supporter
#3
Then the trigger wire is the ACC and I would need to find it. It seems implausible that there is not an ACC going into the factory harness. I have battery disconnected, and the interior disassembled, so I'm kind of in a bind. Hard to understand why GM would not use the standard colors.
 

littleblazer

Gold Supporter
#4
Grab the manuals from mooseman. The wiring for all the radios is in it and color coded. My CPU is being stupid or I'd look it up for you
 

Matt

Silver Supporter
#5
There isn't one in the factory harness, that's why it's easier using an adapter harness when putting in an aftermarket radio. If you want to grab 12v switched power you need to get it from the wiring under the steering wheel, there's a switched 12v there...pink wire.

https://gmtnation.com/forums/threads/12v-switched-power.2001/
 
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paul2005tb

paul2005tb

Silver Supporter
#6
Interesting, and yet my factory radio turns off when I take the key out of the ignition. So what is the signal that is telling the factory radio to turn off ?
 
#7
So what is the signal that is telling the factory radio to turn off ?
The BCM is controlling it through the data bus. This is also how the RAP feature works with the radio and windows being functional when the key is shut off, until one of the doors is opened.
 
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paul2005tb

paul2005tb

Silver Supporter
#8
ouch!.. so there is nothing in the factory GM radio harness that can serve as a ACC/red signal.
There isn't one in the factory harness, that's why it's easier using an adapter harness when putting in an aftermarket radio. If you want to grab 12v switched power you need to get it from the wiring under the steering wheel, there's a switched 12v there...pink wire.
https://gmtnation.com/forums/threads/12v-switched-power.2001/
Just to be clear, I am using the RP5 GM11 adapter harness.
 
#9
In the harness, there is an ACC switched 12V+ line. Just look up the instructions for the harness.
 

djthumper

Administrator
#10
You have the proper adapter to plug into the body harness it will have all the connections that you need. Connect it to the interface box. Connect the radio harness up to the radio and connect to the box. Follow the instructions and you should be good to go.
 

littleblazer

Gold Supporter
#12
I was remembering the radio side of an adapter harness. My bad.
 
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paul2005tb

paul2005tb

Silver Supporter
#13
Ok, so if I understand correctly then the rp5 gm11 adapter module (blue box) is creating an effective ACC/red signal from the factory OEM harness. So it must be using data signals to do it.
 

littleblazer

Gold Supporter
#14
Ok, so if I understand correctly then the rp5 gm11 adapter module (blue box) is creating an effective ACC/red signal from the factory OEM harness. So it must be using data signals to do it.
Yes. Just go wire to wire and you'll be fine.
 
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paul2005tb

paul2005tb

Silver Supporter
#15
Many thanks guys, sorry for the confusion, the instructions/explanations for the rp5 gm11 are exceedingly minimal and I read online resources about finding the ACC and assumed that I had to do that too. If the rp5 gm11 works then it was worth the 90$.
 
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paul2005tb

paul2005tb

Silver Supporter
#16
Well, I am having real trouble with my aftermarket (pioneer 8200nex) radio install. This is beating the day lights out of me. I used the rp5 gm11 harness and there is no sound, and I cant see anything out of my camera. On top of that the doors and locks dont work right. I am putting the original GM factory radio back in until I can figure out what the heck is going on ! I think right now with the entire dash apart I may need to reduce the number of variables I am working with. I have a tiger by the tail, I may have to visit a local car audio shop.

My PAC RP5-GM11 seems to be producing an ACC12. I tested the redwire that the PAC harness provides and sure enough, when the key is on ACC the red wire lights up 12v. Should replacing a stereo HU be this hard ?
 
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southsidesmoka

Silver Supporter
#17
If you can avoid tapping into that voltage under the steering column, you probably should. The cleaner and costlier option, if you have an additional $35 to toss at the installation, check out this Retained Accessory Power and Chime Retention harness. You'll also need a relay to switch your radio off and on (due to current ratings on the harness), but it works very, very well, is absolutely amazing and worth the extra effort you'll have to put in during installation!


Metra LC-GMRC-01 R.A.P. Aftermarket Headunit Harness on Amazon

Metra LC-GMRC-01 Product Page

Below is the missing page from the Metra "manual" that instructs you how to install the turn-on relay, properly (necessary because the Metra harness put out 3 Amps while the headunit requires 10 Amps or more)...seriously, this page wasn't in my printed instruction sheet - so, here it is.

metra-electronics-lc-gmrc-lan-01-page2.png

- southsidesmoka
 
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Mektek

Well-Known Member
#18
Old radios used to be powered by the ACC wire - most newer radios like the OEM are powered from the constant 12v line and the ACC just signals to switch it on.
I'm looking at my gm2000a harness and the black and yellow wires are thicker than the others.
Why would they build a box that was inadequate for its intended purpose????
 
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paul2005tb

paul2005tb

Silver Supporter
#19
finally got my avic8200nex and rp5-gm11 to limp along. Navigation, Sirius, Bluetooth and Rear Camera all work.

Only problem is that the volume is so low. It is much much lower than the OEM radio. How can a 580$ pioneer radio and a 87$ electronic adapter give -20dB lower volume than my original radio ?

The aftermarket radio saga continues... ugh.
 

Matt

Silver Supporter
#20
Does it have a gain adjustment? The Metra does so I'm guessing that the PAC does too.
 

budwich

Well-Known Member
#22
[quote:
finally got my avic8200nex and rp5-gm11 to limp along. Navigation, Sirius, Bluetooth and Rear Camera all work."


OK... but what did you do to get it to work since you went from "nothing" to "mostly working". This might shred some light on why its so "quiet".
 
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paul2005tb

paul2005tb

Silver Supporter
#23
For starters, I still am not sure why nothing was working at first. I did not have the camera properly grounded and that was the reason the camera was not working.

Other than that Im not sure. Edit: I suspect that the RP5GM11 being a microprocessor has something to do with it. I am still working to make sure I have it installed right.

I dont see anything about a Bose sound system on the "window sticker" that I saved from the dealer back in 2005. So as far as I know, there is no Bose sound system on my trailblazer. I did not realize that the RP5-GM11 does not support the base model without Bose. Ouch, aftermarket radio installation is a dog eat dog world!

Edit: I put the factory radio back in and used the fade Front/Rear and Left/Right functions (two functions that I have not used in ages) I realize now that I only have one speaker working, the front right one. Nevertheless with only 1 speaker it is 10dB louder than it is with the new head unit in. I think I need to get the wiring diagram for the speakers out.

If it is the case that the RP5-GM11 is the wrong adapter then what is the best path forward, should I install an amp ? The saga continues !

By the way the rear view camera installed above the rear window is not that bad a view. I kind of like it
 
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#24
It's up to you if you want to swap out the adapter or you could add an amp but then you'd probably have to upgrade the speakers as they might not be able to handle the amp's output. However, you could also connect the speakers directly to the HU's speaker output wires.
 

budwich

Well-Known Member
#25
Just reading the rp5-gm11, I don't see why an outboard amp matters.... outside of the amp on/off wiring, which I assume is not connected.

I have questions around any mute function as perhaps somehow that function is playing a role.

I am still wondering about why nothing worked and then started working (limping)... after throwing a ground on the camera... hmmm.
 
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paul2005tb

paul2005tb

Silver Supporter
#26
Ok, so I think nothing worked at first because the PAC adapter is a computer and it does not immediately work when you plug it in. It has to boot up and go through a software initiation of some kind. I am speculating.

Ok, so Im back tracking to find why 3 of my speakers are not working with the factory radio back. Once this is solved I can think about remaining issues with the new Pioneer HU.

I take out my wiring schematic in ENTERTAINMENT.pdf and on page 4, figure2 for the base model and the abbreviations for the wire colors are cryptic. Can anyone translate the color codes on page 4 ?

TN ?
GY ? (gray ?)
D-GN ? (dark green ?)
L-GN ? (light green ?)
BK (black)
D-BU (dark blue ?)
 

southsidesmoka

Silver Supporter
#28
Ok, so I think nothing worked at first because the PAC adapter is a computer and it does not immediately work when you plug it in. It has to boot up and go through a software initiation of some kind. I am speculating.

Ok, so Im back tracking to find why 3 of my speakers are not working with the factory radio back. Once this is solved I can think about remaining issues with the new Pioneer HU.

I take out my wiring schematic in ENTERTAINMENT.pdf and on page 4, figure2 for the base model and the abbreviations for the wire colors are cryptic. Can anyone translate the color codes on page 4 ?

TN ?
GY ? (gray ?)
D-GN ? (dark green ?)
L-GN ? (light green ?)
BK (black)
D-BU (dark blue ?)
Is the only speaker that is making any sound with the factory radio installed the one in the driver's door? I read somewhere that another Chevy owner had the same problem - I think it was the amp - but the LS doesn't have an amp external from the head unit...was the head unit functioning through all four speakers before the Pioneer install?

- southsidesmoka
 
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paul2005tb

paul2005tb

Silver Supporter
#29
Im certain that the only speaker that works is the passenger side front (right front). With the factory stereo using the fade control: fade left gives no sound at all, and when I fade to the rear, no sound at all. Fantastic sound when I fade right front.
 
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southsidesmoka

Silver Supporter
#30
@psa55 Whip out your DMM, check the color coding for each set of wires for each malfunctioning speaker and proceed to measure the resistance on each set of speaker wires from the harness end. Naturally, you should come up with 4 ohms per driver: however, no resistance means broken wires, disconnected speakers or damaged speakers. Time to troubleshoot, brother.

- southsidesmoka
 

psa55

Well-Known Member
#31
I'll chime in here as this sounds similar to what I was dealing with last year. I only had one working speaker. TB is an LT, no Bose. 3 speakers were toast. I grabbed a couple wires off the front driver's door harness and wired up an old speaker and it worked just fine. Figure the three were blown. I went to the junk yard and found two different TB's that had the Bose system in them. I took the rear speakers at 6.5" Bose speakers out and installed them all the way around. Figured the last working speaker was long for the road. I didn't buy harness adapters, just soldered them up.

FYI, the front Bose speakers won't work as they require an amp to power them as they are larger and have tweeters in them.

My install of my head unit this week is in the appearance forum... New stereo, no power. Think I've got it all sorted out.
 
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paul2005tb

paul2005tb

Silver Supporter
#32
I measured the resistance at the radio connector:
LF 4 ohms
RF 4 ohms (this is the only speaker that works)

LR - open circuit
RR - open circuit

I fear it is time to get the doors apart and further test the connections to the rear door speakers.
 

southsidesmoka

Silver Supporter
#33
I measured the resistance at the radio connector:
LF 4 ohms
RF 4 ohms (this is the only speaker that works)

LR - open circuit
RR - open circuit

I fear it is time to get the doors apart and further test the connections to the rear door speakers.
@paul2005tb Honestly, it sounds to me like you've got a fried Bose amp in your TB. However, if you're certain you don't...

My aftermarket installation culminated a very odd condition. All of my window regulator and motor assemblies are aftermarket replacements; as such, I'm rather sure there is a slight variation in their operation versus that of the OEM assemblies.

When I would roll the rear passenger window down, the bottom of the glass pane would catch the speaker wires of my Rockford Fosgate 1675 and pull the spade connectors loose - disconnecting my speaker...my resolution was to use wire ties to secure the speaker wire out of the way of the glass and I also applied extra pressure to the spades clips themselves so they require more force to connect and disconnect them. Those steps alleviated the problem.

So...are your windows pullings your speaker wires loose? It is a long shot, but it could happen, brother.

Just a heads-up about removing any of the door panels - there is a rather sizeable rubber insulation sheet that is glued to the door around the perimeter of the sheet metal. It's an absolute *$#@# to remove and reapply, as it's originally secured with some thick, industrial strength adhesive. It seems to give when heat, force or a combination thereof is applied. When reapplying it, double-sided automotive-grade tape comes in quite handy to hold it in place.

- southsidesmoka
 
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paul2005tb

paul2005tb

Silver Supporter
#34
Ok, so based on the open circuit measurement of the rear door speakers, I rolled the dice and pulled the rear door speakers out and measured them, sure enough open circuit at the speaker leads, that told me the rear speakers were fried.

So, wanting to get this problem solved in a hurry I ran down to Best Buy and bought 2 "Kicker" brand speakers and replaced them. I turned on the factory radio and the sound was fantastic from all 4 speakers.

Regarding the Left front (driver side) speaker it turned out to be a loose pin connection in the radio connnector. I took my pick and flexed the female side of the connector and it works .
So all 4 speakers now work, in my case it was 2 blown speakers and 1 tired connector.

Now, I have great sound with the factory radio but the new Pioneer radio still sounds like it is 20dB lower in volume relative to the old factory radio. The saga continues !!


Regarding "southsidesmoka" mentioning lowering of the passenger glass window, I need to double check this item because my new speakers are a little deeper than the factory speakers, the glass window could make contact. I'll test it tonight.

Also to the best of my knowledge I dont have an audio amp of any kind, bose or otherwise, I think my speakers connect directly to the factory radio.
 
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Mektek

Well-Known Member
#35
OK, I finally got around to installing the Android stereo that's been sitting on the shelf for the past six months and answer all the speculation about the ACC power.
I picked up 2 Scosche gm2000a boxes on clearance from wally mart. I figured if one was broken maybe the other was good. I was pleasantly surprised to find that both work fine. I tested the current draw on the ACC wire - 4ma when operating! That's right - it's not a typo!

So if your interface box says 3A max - you can't burn it out with your stereo if it draws a few milliamps like mine. Don't waste your time and effort on relays and extra wiring. The relay on the ACC line will draw more power than the radio :bonk:

This is with an Android touch screen DVD navigation radio - plenty of power used for that.
My theory that the ACC is just a signal wire turns out to be correct and I think most newer radios are the same.
The 12v wire on the harness is pitifully thin - If you have a high powered stereo then you should run a separate wire from the BCM power for it. I'll leave mine on the original wire and see how it goes.

If you don't care about RAP and chimes, then there's no problem with running an ACC wire from the ignition harness - the tiny radio load won't cause any problems. If you do, then probably the gm2000a box at wally mart is the cheapest.
 
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southsidesmoka

Silver Supporter
#36
OK, I finally got around to installing the Android stereo that's been sitting on the shelf for the past six months and answer all the speculation about the ACC power.
I picked up 2 Scosche gm2000a boxes on clearance from wally mart. I figured if one was broken maybe the other was good. I was pleasantly surprised to find that both work fine. I tested the current draw on the ACC wire - 4ma when operating! That's right - it's not a typo!

So if your interface box says 3A max - you can't burn it out with your stereo if it draws a few milliamps like mine. Don't waste your time and effort on relays and extra wiring. The relay on the ACC line will draw more power than the radio :bonk:

This is with an Android touch screen DVD navigation radio - plenty of power used for that.
My theory that the ACC is just a signal wire turns out to be correct and I think most newer radios are the same.
The 12v wire on the harness is pitifully thin - If you have a high powered stereo then you should run a separate wire from the BCM power for it. I'll leave mine on the original wire and see how it goes.

If you don't care about RAP and chimes, then there's no problem with running an ACC wire from the ignition harness - the tiny radio load won't cause any problems. If you do, then probably the gm2000a box at wally mart is the cheapest.
Just curious...the Android deck only used 4mA while pumping sound or while at low/no volume? I blew my harness while jamming and driving, not in the garage/service-bay at idle and taking mesurements...

'Tis easy to loose site of the forest when one is in the trees!

- southsidesmoka
 

Mektek

Well-Known Member
#37
Makes no difference. Operating power is drawn from 12v constant - acc wire is just a power on signal.
Old radios were different. The constant 12v was used to maintain settings and were powered from ACC. You need to know what type of radio you have.
 

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