*** solved - remember to hook up your ground wire! ***

I've got a '05 cobalt with Onstar (never use) and the Pioneer speakers.

I bought a Pioneer FH-P8000BT, Metra 70-2103 harness, and the Metra 95-3302 dash kit.

I matched colors and soldered/taped all the wires together that made sense between the harness and the aftermarket HU and tapped the wiper fuse with the red wire. But when I hook it up to the factory harness I'm not getting any power to the HU. None. Zip. Nada. Zilcho.

What's confusing is the factory radio has two connectors but the 70-2103 harness only wires up the larger connector leaving the smaller connector totally out of the loop.

Any ideas?

 

even though you don use the onstar you prolly still need the Expensive GM harness...

i'm not positive though

 

Solved - I was being dumb. I hadn't connected the black ground wire and it won't turn on as a safety feature without the ground connected first.

On a separate note, the smaller factory connector is for XM and you don't need any hook ups for that if you're not using XM.

 

lol Ground being a safty feature? what?

 

its not a safety feature... its completing the circuit

 

I'm pretty sure that smaller plug handles the onstar. Mine had XM but no available onstar in Canada when I bought it 07, and the GMOS LAN 04 retains the onstar but does not interface with factory XM (as far as I know) yet uses both plugs. They changed alot in 07 though so it could be a different plug setup.

Oh yeah, ground wire a saftey feature, not a vital part of all electronics.......all righty then. Is that what the guy at the shop you went to told you when he explained how he fixed it.