I’ve scoured this site for a solution to my problem and see things that start out right but veer off. And I realize that I’m not supposed to post a new thread if the topic has already bans covered by a previous thread so I apologize if it’s been covered before.

I have a 2003 H2 and a while back my climate control module became unresponsive. It still had juice and the display showed a temperature but neither the ***** nor the buttons would do anything. It would only blow hot air and only out of the defrost vents.

So after doing a lot of research, I determined the problem was that module. So I ordered a renewed one, got it installed and it worked perfectly for about four days then it went stupid again. Thinking that the new module went bad after four days, I sent it back for a refund and ordered another one. I installed it, it went through its programming sequence just as the instructions said it would for a successful installation, then unresponsive and no display.

I have a friend tell me if the latest installation wasn’t successful, to check the BCM that it was probably the issue. I might add that over a year ago I lost all power in the passenger door. My friend said that a problem with the BCM could cause issues with the passenger door AND the climate control module.

Has anyone had a similar experience and how did you fix it? If it was a bad BCM, where is it located and how do I change it out? Could something else be causing my issues? It’s starting to warm up here in west Texas and I’m starting to panic over not having AC in the ride. Any help would be greatly appreciated!

Thanks!
Lee

 

I guess the BCM is possible. It is NOT easy to remove but I believe a couple of members here have successfully gotten it out without removing the entire dash.

I say possible because a common place for water leaks, as I'm sure you are aware all H2's will eventually have, is the roof lights. That could allow water to run down the inside of the firewall and potentially get into the BCM.

The BCM is fairly easy to see and unplug. Just removing it is not so easy. It is behind the headlight switch area against the firewall with the plugs facing the headlight switch. Remove that left end panel and you will see it back down in there.

I also have to wonder if possibly the blower resistor might be going bad and maybe that is toasting the control panels? Not sure on that though.

 

Is there any way to remove and test those things? I have a multimeter if I knew where to put the electrodes and what reading it’s supposed to have.

 

To properly test you would need a Tech2 and test in vehicle. That has all of the GM diagnostics and can display live data, test functions, etc.

 

Dang I am definitely tryin not to drop major cash to a mechanic

 

A number of us have ordered a clone Chinese Tech2 from the link below. I've had mine for probably 6 years and it works great. They are using the real GM software so they can access certain modules and functions that no other scanner has like air suspension.

You will want to do a bit of research on the various options to decide on one. The newer MDI type also can work but to use those you have to use a laptop along with it that has some hacked software (or pay for a subscription from ACDelco TDS). The original style Tech2 has it all built in (except for flashing new software - that is the TIS2000 software you see with some of them).

https://www.chinacardiags.com/producttags/gm-tech2.html

 

What MixManSC says is spot on. Yes it is possible the the BCM could do strange things, however it is unlikely to be the cause of power loss to the PDM, it's more like to be a communication problem.

The BCM communicates via Class 2 Serial Data to the Passenger Door Module and HVAC Modules plus others such as the Drivers Door Module, and Air Suspension etc. So the majority of communications must be there, but why the BCM would single out the HVAC seems odd.

The Class 2 Serial Bus links together virtually every module in the vehicle and Splice Pack 205 is one point where many of them link together, including the BCM, HVAC and PDM. Water could have got into the splice pack and corroded the data lines to the HVAC (maybe)

You can easily check the continuity from HVAC C1 Pin B11 (White) to the OBD2 Connector Pin-2, it's just one wire (battery disconnected of course) no doubt you are familiar with the module.

It's also worth noting any after market gear connected to the serial data bus could be a problem, such as a radio and I believe the OnStar can also be problematic. If you have anything like that try unplugging it.

It's odd that your replacement module worked for 4 days, it's almost as there is a bad connection somewhere that got disturbed when you fitted it.

It could even be a Ground Problem, you could check the continuity from HVAC C1 Pin A8 (Black/White) to GND200 Near the Left Kick Panel.

C1 Pin B9 (Black) is also a ground point which goes somewhere relating to the Interior Lights system, but I can find no more references to it.

Hope you find it, please keep us posted.

 

Hi LeeGr we haven't forgotten you, did you make any progress?

 

I’m sorry I haven’t replied sooner to thank you for taking the time to respond in such detail. Would the Tech2 pick up grounding and shorting caused by water issues as well? My mother is in a care home 20 miles away and I try to go visit with her daily plus I’m trying to get a garden going with auto watering so I’m afraid I’ve put my vehicle ac problem on the back burner but as I mentioned before, it’s about to start getting warm in west Texas.

If I bought a Tech2 clone, which would you suggest is the cheapest one I could get by with that would scan the most important parts of the vehicle. I realize I’m asking you to prioritize essential systems.

 

Sorry to hear about your mother.

The Tech2 will not diagnose that fault directly, but it will confirm the HVAC is communicating and allow you to access/monitor it's various functions.

Before buying a Tech2 I'd check the following on the 24-Way HVAC connector C1:-
[Continuity checks should be less than a few Ohms, check the pins for corroded connectors and loose crimps connections/wires]

1. Double-check the module's programming, if it's a Dorman I believe the configuration number is 03 according to their YT video. (
   see here
   )
2. Disconnect the battery negative terminal and check the continuity B11 (White) to 16-Way OBD2 Connector Pin-2 (Purple - Shown as SIG LHS of pic)
   
3. Check continuity from A8 (Black White) to Chassis Ground G200 (Near Left Kick Panel)
4. Check continuity from B9 (Black) to Chassis Ground G203 (Near Right Kick Panel)
5. Reconnect the Battery and check there is 12V on B7 (Orange - Hot All The Time)
6. Start the engine and check there is +12V on B5 (Brown - Hot In Run)

Below is pinout for HVAC connector C1



If all the above are OK, then power should be ON and serial data talking to the HVAC and so it should be functioning.

If any other work has been done, however seemingly unrelated, then check that also, sometime history is everything.

If the problem is deeper, then a Tech2 may help, it takes a little time to to get to used to it's operation as it's used for many vehicles and models, so it's not generic to the Hummer H2.