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Discussion Starter #1
1st off I'm new to the forum and have seen a lot of great info from people so thanks in advance.

I have a 2005 TB that I installed an aftermarket radio in. I didn't buy the (RAT/RAD) connector and just used a basic adapter from WM. Everything worked ok until I need to find a place for the accessory wire which after reading a few places I could use the brown wire on the top right of the wiring harness under the steering column. Radio worked fine and still does but about 2 days after install I notice my TB running rough and get progressively worse. Really felt like a clogged cat or similar issue but could tell huge difference in loss of HP. It got to the the point to where it would barely pull a hill before it quit entirely. On my way home the other day when I turned from a stop as I gave it gas it would hardly go at all until it completely wouldn't move. If I turn the ignition off and back on it idles fine and will move 30-50 yards before there is no response. I unplugged the positive and touched it to the negative for 30 seconds pulled both PCM fuses 28 and 10(I believe 10 is correct) for 30 minutes and plugged it back in hooked up battery and same results. Also since I've had it it has been throwing code P0140 (O2 issue) and right before it stalled out completely it gave me P0756 and P0130 for the 1st time.

Worried I may have fried a PCM/ECM/BCM or something worse. Really don't know where to start. Any and all recommendations appreciated
 

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2002 Pewter ls with automatic trans. 4x2, gray cloth interior.
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Sounds like it may gone in limp mode and the p0140, p0130 are o2 sensor related. May as well swap them as they're fairly cheap and due to its age it's worth it. I think it may just be a coincidence but I've heard some mix feeling about that "brown wire mod" as it's referred to on a corvette forum. Idk how it is with the trailblazer.

Try to just unplug the radio from the back and see if the problem is the same.
 

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Discussion Starter #3
Thanks for the advice. I'm planning on unhooking the radio and go from there. if that's not it I'll search the forum and research limp mode. Thanks
 

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I've have went back through and unhook the radio and reset the computer (by disconnecting + & - from battery touching together for 30 mins & turning headlights on to drain any residual current) and still same results. I'm pretty sure that after more reading and the symptoms (won't go over 2500 roms mainly) that my ol gal is in Limp Mode as "2002 TB LS" stated. Now I need to find what caused Limp Mode and how to get her out of Limp Mode. I have really searched pretty far online and youtube without any real help. TrailVoy seems to be the most reliable and consistent avenue for info but still and dead end here. Again any info is greatly appreciated. Thanks!
 

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2004 chevy trailblazer_lt
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Welcome to the Forum!

One of the first things to try when a TrailBlazer goes into limp mode is to unplug the wire harness from the electronic fan clutch and see if the limp mode goes away. NOTE - do not run the engine very long so it does not overheat.

The electronic fan clutch and the throttle body share the same 5VDC reference circuit, and if the fan clutch goes bad, it draws down the 5 VDC reference voltage and the PCM puts the engine into limp mode. Also, check the wire bundles going to the electric fan clutch and throttle body are intact and not rubbing against metal and shorting out.

Good Luck!
 

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Discussion Starter #6
Chem_Man thanks for info and as suggested I disconnected the fan clutch harness as well check the wires there and at throttle body and reset the PCM (in the order stated previously) and once I started it with the said wiring harness unplugged I got the same results except I received code P0526 (which makes sense) which I cleared. I then went through the process of resetting PCM again and this time hooked said wiring harness back up and received same results (without P0526) so I'm back to square one.

As I stated in 1st post this didn't start until bright after I installed aftermarket radio. Which I have since unplugged the wiring harness from a d remained unplugged.

Again any and all honest suggestions are greatly appreciated. Determined to not give in and take her in to a shop.
 

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2004 chevy trailblazer_lt
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I would next try unplugging the harness connector from the throttle body and make sure the contacts are clean, and then plugging it back in.

If that doesn't work report back and we'll ask for help from a couple of the big guns!
 
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