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2002 chevy trailblazer_lt
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Forget the code reader for now. You MUST find the large battery drain that is likely the cause of the "no communications"
 

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Hey guys I got a 07 ss trailblazer I been working on for 3 months. The problem is the u0100 no communication with pcm. I got another pcm no luck the brought a new pcm and new bcm. Still now luck it's getting power and ground to pcm. But I noticed don't have a 5volt reference. Also I noticed that my battery gauge sits and moves back and forth between 6 volts and 12 volts.
Did you check the big fuses in the front, I don’t have the numbers on hand right now. But it’s the big block fuses. Should be around three or four Of them. All the power to everything is split , if one is no good, a lot of the functions won’t work. And the power to the computer won’t be there for it to work. If you need help to find them, pm me. I known others who had that problem. Good luck.
 

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Hey guys I got a 07 ss trailblazer I been working on for 3 months. The problem is the u0100 no communication with pcm. I got another pcm no luck the brought a new pcm and new bcm. Still now luck it's getting power and ground to pcm. But I noticed don't have a 5volt reference. Also I noticed that my battery gauge sits and moves back and forth between 6 volts and 12
 

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I can't really offer much, except to say that a modern GM PCM 'looks' at components for antitheft reasons. For example, when I put in keyless remote system into my truck because mine didn't have keyless entry, it required me to replace the stereo and airbag control modules from the donor vehicle otherwise it wouldn't work. If you took a steering column from another truck you may need to get the pcm, stereo, and airbag module from the same donor vehicle in order to make everything cooomunicate with each other. Just an idea. Also, I'm puzzled why would you need to replace steering column?
 

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^ to clarify all of what I just said, it is possible the solution is to use the pcm from the donor vehicle the steering column came from....
 

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2021 Trailblazer = overpriced minivan!
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Sstb2007123, I have your reader's bigger brother... the ZR13 and it's a good reader. I agree with TJBaker as to there may be issues with the wiring and the steering column. Different TB's had different steering column options and it is easy to get the wrong one, and that would cause all kinds of issues, especially if the one you need has switches in the steering wheel or (like mine) doesn't have them. Did you get your replacement column from another 07 TB/SS, or from a different year/option package?

Also, while the column was out of the truck, did you take the time to lie on your back with a flashlight and look closely at the wiring in that area under the dash to see if the people that stole it damaged/spliced/mucked up any of the other wiring under there?
 

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2021 Trailblazer = overpriced minivan!
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I can't really offer much, except to say that a modern GM PCM 'looks' at components for antitheft reasons. For example, when I put in keyless remote system into my truck because mine didn't have keyless entry, it required me to replace the stereo and airbag control modules from the donor vehicle otherwise it wouldn't work. If you took a steering column from another truck you may need to get the pcm, stereo, and airbag module from the same donor vehicle in order to make everything cooomunicate with each other. Just an idea. Also, I'm puzzled why would you need to replace steering column?
In his previous posts, he said that the vehicle was bought at a police auction and had been previously stolen. the buttwipes that stole the truck (I can safely assume) tore up the steering column to get to the ignition switch and the steering lock mechanism, and it's just easier to replace the whole column than to buy all of the parts needed separately.
 

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Discussion Starter #28
Thanks for all the help everyone 👍 this thing is kicking my butt. But yea I agree I think the power drain would be the problem. I'm going to check through the OBD2 port and see if the system is reading at 60 ohms. Does anyone have a module chart I can use to trace the system. I think it's two 120 ohm modules in series to make a 60 ohm circuit. 07 ss TB 6.0 ss3
 

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In his previous posts, he said that the vehicle was bought at a police auction and had been previously stolen. the buttwipes that stole the truck (I can safely assume) tore up the steering column to get to the ignition switch and the steering lock mechanism, and it's just easier to replace the whole column than to buy all of the parts needed separately.
^ Replace a steering column is "easy?" I have reservations about that.. Also, as far as I know no Trailblazers ever had steering locks. Did the TB SS's have them? Anyway, if it were me I'd just replace the ignition key assembly and whatever other damaged components. But hey it is anyone's choice. I'm just saying that the PCM appears to need to ensure its still working with whatever components the car originally came with from the factory. Maybe the PCM needs re-flash to "accept" the new, replaced components such as in the steering column. If it were within my abilities with a no-money-is-an-object "test grounds," I'd love to explore that theory....
 

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Discussion Starter #30
Thanks for the help. I brought the pcm and the company was supposed to program it to the VIN. I also replaced the whole steering column it had the power pedals ss3 package like the old one. I even put the old steering column back in and replace the ignition to see if it made a difference.i don't want to give up yet but At this point I'm thinking about getting a msd so the engine will start..I'm wondering if the transmission will work tho. What do u guys think?
 

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I will restate what I said last. I think you need to forget about the communications and whatever else until you find and fix whatever is causing the battery to go dead in 20 minutes. A drain that big is likely preventing any electronics component from operating properly. Only when you have a stable 12 volt power system will you be able to proceed diagnosing any other issues.
 

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Discussion Starter #32
Yea I agree I'm going to try today to try and find the issue any advice on we're to start looking. I have even herd it to be the starter solenoid. Before as the issue of grounding the system
 

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So earlier I asked if the battery goes dead with the key off. If yes then look to things that are powered when the key is off. You said the volts gauge in the dashboard goes back and forth between say 6 to 12. Do you have a meter you can hook to the battery? If yes, do that and watch for the meter to swing like the dash gauge does and pull fuses till it stops. Without a good current meter about all you can do is pull fuses and such to see what area is causing the draw.
 

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How old is this battery also? If it's an old battery that has been run dead a bunch of times it is likely time to replace it,,, BUT!!,, An old battery wouldn't cause that high low high gauge swing you spoke of.
 

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^ Replace a steering column is "easy?" I have reservations about that.. Also, as far as I know no Trailblazers ever had steering locks. Did the TB SS's have them? Anyway, if it were me I'd just replace the ignition key assembly and whatever other damaged components. But hey it is anyone's choice. I'm just saying that the PCM appears to need to ensure its still working with whatever components the car originally came with from the factory. Maybe the PCM needs re-flash to "accept" the new, replaced components such as in the steering column. If it were within my abilities with a no-money-is-an-object "test grounds," I'd love to explore that theory....
To remove the steering column is not that hard, I did my column a few years back, so I might be forgetting something... Remove the trim below the column, unplug all the connections, Remove or loosen the coupler, and remove 4 bolts or nuts (I forget). the last time I did it I had mine out in about 15 min... The first time took me about 45 min, but it is not difficult to do. It takes way less time putting it back together as getting some of the plugs disconnected can be a pain...

IF you replace the column try to get one from the same year. I know there is a difference between 2005 and 2006 as they included the stabilitrack or whatever it is called in 2006. It might fit on an earlier model, but a early model problably would not work on a later model without modification.
 

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Discussion Starter #36
I will try that .I read my can bus system thru odb2 and it was 120 ohm I think it should be 60 ohm. Two 120ohms in parallel. so I'm thinking one of the modules and the system is the problem and is shorting
 

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Auto electronics = voodoo to me, but I'm guessing a high powered vehicle like the SS will use higher ohm rating. I know that's not a helpful answer....
 

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^ Replace a steering column is "easy?" I have reservations about that.. Also, as far as I know no Trailblazers ever had steering locks.
I didn't say it was easy...I said it was easier than trying to get all of the little bits nad pieces that were broken separately. I have changed some suburban steering columns before, and other than being time consuming, they aren't too bad. My 2002 TB EXT does have a steering wheel lock built in. I can't say if other flavors do or not
 

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Also, you may have to reflash the BCM (body control module) as well to get the steering column/radio/etc to work together. GM deliberately went to great lengths to make these vehicles a PITA to work on the electrical stuff. I've been old that if you replace an airbag, with a good used one, you have to have the bcm reflashed to find the new serial number, or else it wouldn't work. I don't know if that one is true, but I heard it somewhere.
 

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^ Fully agree that GM makes electronics difficult. But, I'm certain that applies across various automakers. No matter the brand, is difficult to replace ANY piece of electronics that didn't come OEM from the factory.
 
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