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2005 chevy
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Discussion Starter #1
OK, so last night I decided to swap all my filament cluster lights to LED. Went pretty smoothly, took the board out to the truck for a successful test before putting it back together. Went to reinstall the cluster, and while showing off to one of my neighbors, noticed that all of the cluster lights remained on while the truck was off, and key out of the ignition. :ugh:

Remove the cluster and recheck everything, one of the resistors had gotten pushed a bit, causing one of the leads to touch the board where some traces were. Small adjustment, and all was right with the world (or so I thought) Put the cluster back in, stepper motors gave a quick buzz, and the lights worked properly. BUT, now the odometer and gear selector was out. :duh:

In the number of threads I've read this morning, I've checked fuse #24 up front, all of the TBC fuses (front and rear) with a fuse tester (handy lil device I didn't know I had) and confirmed proper voltage on the orange and pink wires in the cluster harness. I did see some suggestions of bad grounds, but I'm pretty sure if I shorted something, that wasn't gonna be the issue.

Are there any other things I can check/fix on my own, or am I screwed and gonna have to send this out to get fixed (or worse buy another cluster) :sadcry:
 

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2004 gmc
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26,181 Posts
ODO and gear selector display is a high voltage fluorescent display, so I think you have permanent damage. Plenty of repair vendors on Ebay for around $100.
 

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2003 chevy trailblazer_ls
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163 Posts
Hey if that is truly the problem, I have a guy I went with that fixed 2 of my traces for 30 bucks out the door.

The guy was FREAKING awesome and really quick shipping.

PM me if you want his info so I don't break any site rules..
 

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2002 chevy trailblazer_ls
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7,255 Posts
I am no electrical genius, but it sounds to me like something shorted out. I have looked closely at the gauge cluster, as I just had to replace mine due to a broken circuit on the fuel gauge leads. I thought about taking the chip located next to the odo display off to transfer to the new cluster so I didn't have to reprogram the mileage, but even the work involved in that proved to daunting and I decided to just let me truck be TMU until I go to sell, in which case I will have it reprogrammed. Some of that circuitry is just too intricate for a novice. The way I see it, your options are to send it out for repair, try to repair it yourself, or buy a replacement. Some ebay vendors offer a repair service for @ $100, but there are no guarantees and there will be downtime of about a week or so. Buying a used replacement should run under $100 but add an additional $100 to get it reprogrammed.

Ironically, I broke the circuit for the fuel gauge when I did the LEDs in my cluster. This happened because I didn't remove the needle correctly, messed up the stepper motor, and didn't de-solder it enough before pulling the old motor for replacement. It resulted in the breaking of a ring terminal. My used cluster was only $60, but it reads 30k more miles than I actually have. I can live with that for now.
 

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2005 chevy
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Discussion Starter #5
:mad: Yeah, you guys are confirming my suspicions. Is the truck's mileage stored in the BCM (or anywhere else) as well as the cluster? I know my monthly OnStar reports list it, since I can't afford a replacement right now, I want to make sure I can get accurate mileage if I have to sit on it for a month.
 

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2002 chevy trailblazer_ls
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Yes, the mileage is stored in the cluster and the PCM. If you cam find a local place to reprogram a new cluster, it'll take probably 5 minutes and they plug into the obd port. If it has to be sent away, you need to send both clusters so they can match the new to the old. Be careful with it because if there is even one mile difference, you will need to disclose it because it is "fraud" if you try to sell or trade it without doing so.
 

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2005 chevy trailblazer_lt
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363 Posts
Yes, the mileage is stored in the cluster and the PCM. If you cam find a local place to reprogram a new cluster, it'll take probably 5 minutes and they plug into the obd port. If it has to be sent away, you need to send both clusters so they can match the new to the old. Be careful with it because if there is even one mile difference, you will need to disclose it because it is "fraud" if you try to sell or trade it without doing so.
The PCM stores mileage as well? How does this come into play when you have a used but new-to-you tuned core PCM so that you can keep the stock one as a backup?
 

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2003 chevy trailblazer_lt
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133 Posts
Don't forget to let us know hohw it goes. I'm tearing my cluster out yet again! Hope you have better luck with yours! You should have some good karma coming for the help you have been.
 

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2005 chevy
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Discussion Starter #9
Will do. I sent a couple of emails out to some local repair places for quotes, so we'll see what they say. :coffee Hopefully it won't deplete the funds in my good karma bank account. :hissy:
 

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2002 chevy trailblazer_ls
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The PCM stores mileage as well? How does this come into play when you have a used but new-to-you tuned core PCM so that you can keep the stock one as a backup?
Gm, as well as probably most other car companies, store the mileage and hours not only in the gauge cluster, but also in several other places. This ensures that people can not alter the vehicle mileage and get away with it, or at least dissuades them from doing so. I think it is the cluster, PCM, BCM, and maybe somewhere else. That's why a replacement PCM get reflashed, to essentially transfer the old files from the truck to the computer. That also why there is a $5000 machine needed to do this. If they do not all match, the title is considered tmu and vehicle value is severely compromised. Dealerships and private sellers can get in big trouble for not disclosing inaccuracies.
 

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2009 chevy
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6,431 Posts
Carlton, I don't know about the mileage (I could look it up), but I don't think that's your problem.

The mileage and gear selection are on a printed circuit display, your problem is that the display is not lighting.
You may have broken a pc run.
Use a good magnifying glass and scan each run for a crack (usually straight across). If you find one, they are easy to fix.

The PCM does send a signal to the cluster, and to this display, to tell the driver what position the gear selector is in.

When you move the selector (with the key on), does the small bar (the one that would normally be under the position light PRND321) light?

BTW, you did have the key on when checking the display? :undecided
 

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2005 chevy
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Discussion Starter #12
Carlton, I don't know about the mileage (I could look it up), but I don't think that's your problem.

The mileage and gear selection are on a printed circuit display, your problem is that the display is not lighting.
You may have broken a pc run.
Use a good magnifying glass and scan each run for a crack (usually straight across). If you find one, they are easy to fix.

The PCM does send a signal to the cluster, and to this display, to tell the driver what position the gear selector is in.

When you move the selector (with the key on), does the small bar (the one that would normally be under the position light PRND321) light?

BTW, you did have the key on when checking the display? :undecided
Interesting theory, that should keep me busy for a while. I think I would have to locate that box of extra patience I've got stashed around here somewhere. Sounds like I'll definitely need it. :bonk:Sounds a bit like when people need to fix their rear defrost grid.

Neither the gear selection, the PRND321, or odometer light up at any point. Ran some errands today, and glanced down hoping against hope quite a few times :hopeless
 

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2009 chevy
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Sounds a bit like when people need to fix their rear defrost grid.
Haha, a lot easier, and a lot more successful


Neither the gear selection, the PRND321, or odometer light up at any point. Ran some errands today, and glanced down hoping against hope quite a few times :hopeless
Ok, looks like it's circuit board related.
 

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2005 chevy trailblazer_lt
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Gm, as well as probably most other car companies, store the mileage and hours not only in the gauge cluster, but also in several other places. This ensures that people can not alter the vehicle mileage and get away with it, or at least dissuades them from doing so. I think it is the cluster, PCM, BCM, and maybe somewhere else. That's why a replacement PCM get reflashed, to essentially transfer the old files from the truck to the computer. That also why there is a $5000 machine needed to do this. If they do not all match, the title is considered tmu and vehicle value is severely compromised. Dealerships and private sellers can get in big trouble for not disclosing inaccuracies.
Well, how about those of us like me who are planning on buying, or those that have already bought, a replacement tuned PCM from a place like PCM4Less for more performance and driveability? I am going to buy a tuned PCM but I will keep my stock one as a backup. How will the mileage ever match? Are you sure that mileage is stored on the PCM?
 

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2005 chevy
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Discussion Starter #15
Quick mini update, I made some calls and shot off some emails to some local speedometer repair places, and one has gotten back to me with some actual quotes. $130+tax if it's repairable, $125 if I can provide a new cluster to be programmed with VIN/mileage, and $225 if they find a cluster for me. He said the last TB he saw with this problem ended up needing a new cluster though. I think what I'm gonna do is put all the stock bulbs back in, take it to Carmax and see if they'll replace it under warranty. No idea how close of a look they'll take, but I'm guessing either it's covered, or it ain't.
 

:rolleyes: As long as the autolights don't come on and they see damn near everything else has blue LEDs in it, they won't suspect I've done any tinkering and broke something... :duh:

For a $50 deductible, it won't hurt to try. If not, then I'll Ebay a used cluster and get it flashed.

And about the mileage storage, I shot an email off to OnStar (since mileage is listed on their reports) asking where they pull that data from. They instructed me to call in and speak to their tech department, which I did. It took a while to get the guy to understand what I was asking, and he gave me a fluff answer that says he didn't really know the answer for sure. He did confirm that although a cluster may go bad, the vehicle will continue to update it's mileage (somewhere) and it would be reflected on my monthly reports. Leads me back to my assumption it would be in the BCM, but that's just my guess.
 

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2003 chevy trailblazer_lt
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Thanks for the update. I was hoping it was easier (cheaper) than that but it is what it is. I still haven't found anything out of the ordinary with mine so it looks like a replacement. Guess I'll be looking for a new cluster as well (amongst so many other things). Good luck to ya and let me know if ya find some good deals.

:bonk:
 

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2005 chevy
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Discussion Starter #18
If you weren't late to the party, you coulda had pizza and wings man!! :raspberry

Thanks for the update. I was hoping it was easier (cheaper) than that but it is what it is. I still haven't found anything out of the ordinary with mine so it looks like a replacement. Guess I'll be looking for a new cluster as well (amongst so many other things). Good luck to ya and let me know if ya find some good deals.

:bonk:
I started keeping an eye on what's out there, there are some clusters that are pretty cheap. I hope to keep mine for the white gauge faces, so the physical condition wouldn't be too big of a deal since I just need the circuit board.
 
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