Rocket Man's 2008 Bagged CC Silverado Build AKA "THE MACHINE"

[Rocket Man]

I turned on the ac a while back for the first time this year and couldn’t get any cold air out. I kind of forgot about it until a couple days ago so I hooked up the tech 2 and pulled this code B3933. It looks like either the evaporators temp sensor is bad or, more likely, it’s a pinched/ shorted wire and I’m thinking it’s in the same harness as the driver airbag that shows an open or short to ground. I wasn’t real worried about the airbag but the ac? That’s important. Either way, the dash has to come out to replace that sensor. So it looks like I’ll be pulling the dash to inspect for a pinched harness after all. I ordered the sensor too just in case. Psh.

 

[Rocket Man]

Well shit. I don’t see any pinched harness or wires. I hooked everything back up temporarily and the same 2 codes show up, driver side airbag deployment loop and AC condenser circuit. I haven’t even found that stupid sensor yet. I need to YouTube that sucker. I’m thinking I’ll need to find out the color of the airbag wires and trace them through the harnesses. What a *****.

 

[Tonyrodz]

Well shit. I don’t see any pinched harness or wires. I hooked everything back up temporarily and the same 2 codes show up, driver side airbag deployment loop and AC condenser circuit. I haven’t even found that stupid sensor yet. I need to YouTube that sucker. I’m thinking I’ll need to find out the color of the airbag wires and trace them through the harnesses. What a *****. View attachment 248255

What a pita!

 

[Rocket Man]

What a pita!

Oh yeah. I only wanted to do that job once, when I originally did the dash swap. At least I didn’t make a mistake from what I see. But it doesn’t help I’m stumped on the airbag. I even bought the tool that imitates the airbag and you can plug it in at the different connectors but I still can’t find the problem. Even swapped out the bcm. Sucks.

 

[Tonyrodz]

Oh yeah. I only wanted to do that job once, when I originally did the dash swap. At least I didn’t make a mistake from what I see. But it doesn’t help I’m stumped on the airbag. I even bought the tool that imitates the airbag and you can plug it in at the different connectors but I still can’t find the problem. Even swapped out the bcm. Sucks.

I have faith in you, you're a determined SOB. You'll figure it out. My airbag light us on in both my Hoe and work van. Scanner says it's the same driver side front impact sensor on both.

 

[Bear77]

I have faith in you, you're a determined SOB. You'll figure it out. My airbag light us on in both my Hoe and work van. Scanner says it's the same driver side front impact sensor on both.

The irony!


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[Rocket Man]

Oh damn, I think I figured out the ac problem. I’m getting dtc b3933 AC evaporator sensor open or short to battery. That dtc doesn’t even show up in alldatadiy. I looked up the sensor on a GM dealer parts site and ordered it, and the YouTube videos I saw were for 2011 Tahoe’s or similar. Alldatadiy didn’t show any info on replacing the sensor either, which I thought was weird. Also some GM parts sites don’t list the sensor, and the exploded parts views don’t show it. Weird, huh? Anyway it looked like it was on top of the evaporator under the passenger airbag in the videos fit the Tahoes. It’s not there in my truck . I looked everywhere, can’t find the sensor. Then I came across this TSB.


Subject: Models:
PRELIMINARY INFORMATION
Reduced Air Flow From HVAC Vents And DTC B3933 SYM05 (HVAC Control Head Not Programmed)
2007-2009 Cadillac Escalade Models
2007-2009 Chevrolet Avalanche, Silverado, Suburban, Tahoe 2007-2009 GMC Sierra, Yukon Models
2008-2009 Hummer H2 ModelsNON-HYBRID
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
Some owners may comment of reduced air flow from the HVAC dash vents and there will be a DTC B3933 SYM05 set in the HVAC control head. This DTC is for an Evaporator Air Temperature Sensor, which is NOT used on the models listed above. The reduced air flow from the HVAC vents is due to the evaporator core freezing up.
These issues may be caused by the HVAC control head not being programmed AFTER being replaced (as instructed in SI).
Note: Starting in model year 2010, the models listed above use an Evaporator Air Temperature Sensor. Programming of the HVAC control head is required to set that module up for vehicle features by model year.
Recommendation/Instructions
To correct this concern, SPS program the HVAC control head using TIS2WEB. When SPS programming the HVAC control head, make sure "Replace and Program" is selected in TIS2WEB.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.



Yes, if you remember, I did replace the HVAC control head. I was trying to use TIS Web to flash my original unit with updated firmware when it bricked itself, so I bought a used one from LKQ. And I did NOT want to brick that one, so I didn’t mess with flashing it. Well, now it looks like I have to. Sure hope it fixes the ac. Now as for the airbag- I have the entire truck tore apart and I’m gonna find out which pair of wires those are and trace those mofos.

 

[Bear77]

As diligent as always...no doubt you’ll find it! And when you do, you’ll kick yourself for “overlooking” it!


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[gat0r]

you may need to do some write ups for Alldatadiy

 

[Rocket Man]

I hooked up the laptop and the Tech2 this morning and after an issue with one of the connections, I got the HVAC control module programmed, cleared the history DTC’s and voila. Ice cold AC again. No DTC’s. Now I’m gonna troubleshoot the open circuit in the airbag.