First GM truck, 2013 Tahoe PPV

[Caddylack]

Being a PPV and not having a lot of the common options, they probably just use the normal/commonly-optioned harness and leave the wires unterminated for upfitter use.

I will bet against you on that. Have you seen the electrical system on the PPV? I'm pretty sure I have the regular upfitter box in addition to this giant coil of wires. There are 8 gauge power and ground leads throughout the entire vehicle, and there is a power distribution block under the hood that looks like something from a crazy audio system.

What 14-pin connector?

The GM radios of this era use two connectors, one with 14 pins and one with 16 pins. You might think of the 14-pin connector as being 12-pin if you don't count the power and ground, but the pins are numbered 1-14.

 

[89Suburban]

Welcome!

 

[iamdub]

I will bet against you on that. Have you seen the electrical system on the PPV? I'm pretty sure I have the regular upfitter box in addition to this giant coil of wires. There are 8 gauge power and ground leads throughout the entire vehicle, and there is a power distribution block under the hood that looks like something from a crazy audio system.

All I've ever seen of the PPV electrical system is the rat's nest from all the aftermarket add-ons being ripped out. I had to go back and re-read your description. I clearly misunderstood. So, GM provides all these extra circuits from the factory to support the accessories. I always thought those were aftermarket. Pretty damned cool and convenient!

The GM radios of this era use two connectors, one with 14 pins and one with 16 pins. You might think of the 14-pin connector as being 12-pin if you don't count the power and ground, but the pins are numbered 1-14.

Oh- at the radio itself. It'd be a bit of a breakthrough to find if that white wire is a viable switched 12V source.

 

[Caddylack]

I found a post the other day on some forum where a guy claimed to have found a switched 12v wire in the radio harness. Although, I am wondering if it's just a switched 12v output for the other electronics in the car, rather than an input to the radio itself. Meaning, theoretically you would still need to connect switched 12v power to this wire for it to function.

I've hit my first real roadblock, and I'm going to bed stumped tonight...

I was not able to get any power from the supposed factory 12v switched lead. I'm now paranoid that some or all of this harness has been cut somewhere, but I can't trace it very far.

Next, I tried to connect the Malibu switched and constant wires together just to test the head unit, and it made no difference. I still can't get it to actually turn on; it's acting like it would if the car were off with no key in the ignition. Then I grabbed one of my cheap but brand new head units and tried to connect it the same way... It literally blew up immediately in my hands and started smoking. That might just be a coincidence, since it was cheap.

I just looked at the supposed upfitter panel that was referenced in another thread, and mine doesn't look anything like the pics I've seen. I'm suddenly back to the timeless question, "where the hell do I get switched 12v power from?"

At this point I might just put the Malibu radio back on the shelf and proceed with just wiring up an aftermarket unit. I need to be done with this, because I've spent too much time on virtually nothing.

 

[Sparksalot]

All I've ever seen of the PPV electrical system is the rat's nest from all the aftermarket add-ons being ripped out. I had to go back and re-read your description. I clearly misunderstood. So, GM provides all these extra circuits from the factory to support the accessories. I always thought those were aftermarket. Pretty damned cool and convenient!




Oh- at the radio itself. It'd be a bit of a breakthrough to find if that white wire is a viable switched 12V source.

Most of the extra wiring harness was intact in theothertwin when I got it. I did some recreating in thecopcar. It was only after I got the second twin that I realized how much thecopear was savaged during decommissioning.

the big 125 amp power feed into the cabin was a fantastic find I knew nothing about when I bought the first one.

 

[iamdub]

I found a post the other day on some forum where a guy claimed to have found a switched 12v wire in the radio harness. Although, I am wondering if it's just a switched 12v output for the other electronics in the car, rather than an input to the radio itself. Meaning, theoretically you would still need to connect switched 12v power to this wire for it to function.

Did the Malibu have a factory amp or do the models that have an amp have that same HU? Could that be a switched from the HU to turn on an amp?

Next, I tried to connect the Malibu switched and constant wires together just to test the head unit, and it made no difference. I still can't get it to actually turn on; it's acting like it would if the car were off with no key in the ignition.

Could this be the Theft Lock? I don't know what these specific units do if there's a VIN mismatch. The ones with the touchscreen display show a blue screen and a "THEFT LOCK" message.

 

[Caddylack]

Did the Malibu have a factory amp or do the models that have an amp have that same HU? Could that be a switched from the HU to turn on an amp?

I believe this head unit was only available with the Bose system.

Yes, I believe the white wire in the Tahoe harness and the pink wire in the Malibu harness are both "output" turn-ons. In the Malibu it goes directly to the Bose amp, and I would guess on the civilian Tahoe it would be for rear entertainment stuff. On the PPV, I don't have a guess.

Every piece of documentation I've come across has clearly said there is no accessory/switched 12v input to the factory Tahoe radio.

Wait a second... I've been short on sleep for the past couple of nights and now I feel like there is something wrong with my logic here. Why was I even trying to connect power to those wires? I will look at the diagrams again as soon as I wake up. I bet I forgot a pin in the harness or something.

Could this be the Theft Lock? I don't know what these specific units do if there's a VIN mismatch. The ones with the touchscreen display show a blue screen and a "THEFT LOCK" message.

Theft lock was my first thought, but everything I've read says that it would give me some sort of message on the screen. The head unit is acting like it has power but doesn't have an "on" button, basically. I yanked the little chip out of the motherboard and it changed nothing.

The other thing I considered is this...

The base factory radio in our trucks has no switched 12v input, and it can also match VINs with the vehicle. This tells me that there must be some communication between the radio and the computer system, maybe through the GMLAN. Could this be just as simple as the Tahoe not recognizing the Malibu head unit on a computer level? I don't think this radio was ever offered in a truck. Damn these newer cars.

 

[swathdiver]

Welcome! You can download some helpful guides for your new ride from GMs Upfitter website. You can get the wiring diagrams buy purchasing a subscription to the shop manual at AllDataDIY. Guys on ebay sell CDs or downloads to it as well.

 

[iamdub]

The base factory radio in our trucks has no switched 12v input, and it can also match VINs with the vehicle. This tells me that there must be some communication between the radio and the computer system, maybe through the GMLAN. Could this be just as simple as the Tahoe not recognizing the Malibu head unit on a computer level? I don't think this radio was ever offered in a truck. Damn these newer cars.

Yes, all OEM HUs are VIN-locked. Pending verification of your wiring, it's looking like the radio doesn't understand the "turn on" command from the Tahoe.

 

[Caddylack]

Okay, after a few sips of coffee I see what I did.

Everything was fine until I identified that white wire in the Tahoe harness yesterday, and that's where the sleep deprivation logic took over. I started thinking that this white wire may have been a turn-on wire FOR the radio, when in reality, it seems to be a turn-on lead FROM the radio to other devices. Somehow, I managed to get the pink wire from the Malibu mixed up in all of this, even though I have known for several days that the pink wire is an output to the Bose amp.

I'm all ready to put in an aftermarket head unit right now, but I realized there may be a snag with my ghetto chime retention setup...

Ultimately, the chime sound still outputs through the regular speaker wires on the factory radio, yes? In that case, I'm suddenly not sure how I would be able to get the chime sound to play over speakers that are wired to an aftermarket head unit.


I feel like the chime alerts may be more important on a PPV, since all of the "idiot-proofing" is deleted by the factory. There are no automatic headlights, and there's nothing stopping you from locking your keys in the car with the engine running.

Something cool I wanted to mention:

Beneath the instrument panel, I found a male/female connection with 8 pins for each of the 8 F/R speaker wires. In other words, my amp is wired for me. I can just pull the pins out of these connectors and put them into the connectors on the amp. I wonder if the civilian trucks have a harness that would "T" in here for the factory amplified systems?

It's only a matter of time before these trucks catch on with the "serious" audio crowd. It's literally the only car you can buy that is already factory-wired front to back to this degree (125A to the rear cargo area, wow).