[nissandr]

Like title says anyone have one for sale pm me, gen5 no longer sells it due to parts shortage

[Msquared]

Might want to try the PAC LPHGM72 breakout harness. It looks to have the correct connectors and says it is compatible with IOS.

[keep_hope_alive]

This is the harness I used. What I came to realize is that I think my harness is pinned improperly and it affected the high speed CAN bus - which no longer communicates properly so I've lost all GPS, internet, OnStar, etc. GM dealer wouldn't warranty the issue because of the aftermarket harness. They suspect the pin sizes are wrong, affecting connectivity.

Further, I was checking the pinouts and it appears two wires are mixed up - a rear speaker wire and a high speed CAN. Thankfully, I removed rear speakers prior to installing this so I didn't fry anything.

The harness is a lovely idea, but I regret installing it. I should have just cut the speaker wires to intercept and avoided the whole hassle using this harness has caused.

[Msquared]

Oh damn! Well thanks for the PSA on that.

[p47dman]

I user Metra LOC-GMH3 breakout harness.

[Msquared]

Originally Posted by keep_hope_alive

This is the harness I used. What I came to realize is that I think my harness is pinned improperly and it affected the high speed CAN bus - which no longer communicates properly so I've lost all GPS, internet, OnStar, etc. GM dealer wouldn't warranty the issue because of the aftermarket harness. They suspect the pin sizes are wrong, affecting connectivity.

Further, I was checking the pinouts and it appears two wires are mixed up - a rear speaker wire and a high speed CAN. Thankfully, I removed rear speakers prior to installing this so I didn't fry anything.

Looking at this situation a bit further in the context of the Metra breakout harness referenced by p47dman. If you check the Metra catalog they show the LOC-GMH3 that p47 used, which works correctly on a car with IOS. They also show the LOC-GMH4 which is labeled for use with cars that have OIR systems, and it uses an aqua/green(ish) colored plug on one connector and white on the other, vs the grey and black for the GMH3. I saw some reviews where people with IOS systems ordered the GMH4 harness and it also made their GPS and other functions go haywire.

Likewise, PAC have the LPHGM72 harness with grey and black connectors for cars with IOS radios and also the LPHGM71 with white and aqua connectors for the IOR system. I suspect that they have garbled the wiring connections, such that the LPHGM72 package that keep_hope_alive got is wired for IOR cars, or maybe the just put the entire wrong harness in the package. I think I am I seeing that his harness has a white connector and a gray connector, which is a hodgepodge of both models! In any case, PAC appears to have some issues with quality control either in its manufacture or packing.

Bottom line: at this point I'd go with the Metra LOC-GMH3 because it appears to connect and function properly.

[MN61SS2K24]

keep_hope_alive I had the same problem and contacted PAC. They told me they had a few with the wrong pinout and they sent me the fix as a PDF. So they knew the problem and it’s like 4 wires that are pinned wrong.
My Onstar wasn’t working either so I unplugged everything and I’ll fix it during winter.