Yes, there could be a short in the IPC, however the cig/dlc fuse blows too?

 

The fuse issue is worrying and hasn't gone away, so it's essential to find out why it blows, it could potentially be a fire hazard. This "unknown something" is trying to draw over 15A and fuses typically blow well over their rated current.

Though it could be a red-herring, it's a solid clue. Maybe this "unknown something" is also connected to the OBD2 bus and affecting communications such as MIL operation.

You may have missed my previous comment, but does your aftermarket radio turn off with the ignition?

Also is your radio ON when the MIL come on?

Imagine you changing your IPC and still being left with the same problem - expensive!

Just to note I'm still looking for the route the wiring takes from the fuse to the OBD2 Connector and the Cigar Lighter.

 

Start by looking under the UHFB, tapped wires/shorts are easily found!

 

Ok, here’s what I found!

first, the radio is always on when the CEl comes and goes!
second, I see a “upgradeable xpresskit” box (i believe it’s an alarm) by the fuse box on the side of the cluster, I’ll post a picture later
the wire that it’s showed on my previous picture is connected to a ground in front of the battery (on the chassis)

ill post pictures of all of this later

 

I think you have found a clue. Xpresskit is a product from DEI which yes is often related to alarm systems, also remote start systems. Often for interfacing to allow a remote start or alarm to override the factory security and sometime to control door locks etc. via a data bus tie in. Those also need constant power and the cig power circuit is quite often the circuit of choice to grab that power from.

If it makes you feel any better.... I'm in the middle of pulling all of the remains of an old defunct remote start out of my GMC and have actually spent the last few hours meticulously and carefully undoing it all and repairing any splices in the factory wiring.... It is quite a process to do and not terribly fun but I need to do it.. There are wires tied in on the bottom of the steering column, at the connections to the BCM, to the fuse boxes, and even the lower kick panels (for door lock wires), and to under the hood. Quite a mess to sort out but in a way satisfying to do. I already have quite a pile of wires and plugs piling up on the floor that I have removed.

 

Now I don’t know if I should just unplug it! What about if it messes up with my door lock and stuff like that?

 

well then replugging it should return you to where you where. so i would un plug it and see.
i have a parrot bt module installed on my h2 that the previous owner had installed. they patched that thing all the way down the center console on to the amp. if i disconnect it then i loose my audio out from the factory radio so i just decided to go onto the ebay and by the parts that where missing to make it work. they really went deep into the wiring and i felt like the simplest course was to leave it alone. but at least they used solder and heat shrink to do the job and meticulously ran all the wiring so not a diy installer for sure.
the other issue i had was a U1000 code that i tracked back to a sirrius satelite module that had also been installed. that one i did remove as the module was bad it seems this one the wire harness was just spliced in and not soldered so removed all of it. probably dealer installed after the fact.

 

I guess there are 2 trains of thought on this one, leave it as it is or try to put your Hummer back to what it was when it was sold by GM. Personally, I would start with the DEI module, if possible to remove ANYTHING that came from DEI. Over the years and in countless episodes with vehicles I have had nothing but problems with vehicles that had left overs from previous owners that used some type of DEI product. Blowing fuses and cooked wiring, things not working as they should, engines shutting down, no start, door locks not working, dead batteries. The list goes on an on. Sorry if this sounds negative, but I comes for the school of hard knocks, (and many were DEI products, lol)

Once you have eliminated the DEI stuff go after the audio issues, at least you know you vehicle won't burn up or leave you stranded because of some defunct or badly installed aftermarket alarm system addon.

Sorry if this sounds negative, but I comes for the school of hard knocks (as many of us on this forum as well) , (and many were DEI products, lol)

 

Phil Pereira
Seems you're making progress, on the right track and also doing well with your investigations.

To help with this, a few more questions:-

1. What model year is your H2? The comms bus depends on the year i.e. Serial = [2003 - 2007] and CAN-Bus = [2008-2009] ) this determines which XPresskit unit
2. Yes please upload a picture or confirm the model of the XPresskit(s) fitted? Some of their diagrams show connections to either OBD2 connector Pin 2[Serial] such as gmdlbp or Pin 1 [CAN] for CANMAX400
3. What model radio is fitted so we check any Comms Bus Connections it may have?

It's hard to figure-out what the consequences of unplugging the XPresskit would be without more details, same goes for the radio.

Take a look at the rear of your OBD2 connector (actually called the Data Link connector) and check the wiring there (BTW they could have tapped-in elsewhere) e.g. this is what virgin '05 wiring looks like :-


The 4 wires are as follows:-

• Pin 16 = Orange = Power
• Pin 5 = Black+White = Ground (G200)
• Pin 4 = Black = Ground (G203
• Pin 2 = Purple = Data (possibly tapped into)

If you turn the radio OFF and the fault goes away, then it could be the culprit.

Hope we are helping and not confusing.

 

You guys are definitely helping me not confusing me at all!
this morning I took out the roof light bar and its harness, that black relay that you can see on my previous picture is from the light bar as I’ve said, it wasn’t even connected and the wires were strapped!
my hummer is a H2 2004 and the radio is some China stuff that they’ve put in! The brand is power ackoustik!
there’s some pictures of the XK01 and yeah it’s connected to the Obd port as you can see!