Speedometer, power seats, radio, locks and other features don't work?

Tiny
JEFF HERMAN
  • MEMBER
  • 2004 CHEVROLET TRAILBLAZER
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 214,000 MILES
This vehicle has multiple issues which appear to be electrical. Speedometer, power seats, radio, locks, and other features don't work. I haven't checked fuses yet, but it occurred to me with so many things not working it might be ECM related. Is this possible and could it affect transmission? No upshift from 2nd. The truck also stalls after running for a few minutes. Haven't checked spark when it happens yet. We're suspecting crank sensor, but could all these be related? Right now, we are in a deep freeze here. Lol
Monday, January 30th, 2023 AT 12:00 PM

10 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
Yep, the county is under snow for the most part, so hang in there. We must check the fuses first.

Here is a guide and the fuse locations as well:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

There is a driver's door module that sounds like it is not working or the battery fuse 125 amp in the under-hood fuse panel has gone out. Please check the fuses with the key on. Check out the images (below). Please let us know what you find. We are interested to see what it is.
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Monday, January 30th, 2023 AT 5:03 PM
Tiny
JEFF HERMAN
  • MEMBER
  • 437 POSTS
I found the 125A mega fuse blown. After replacing it power windows, seats, gages, radio work. Car won't start, haven't checked fuel or spark. Would that fuse power the PCM and be a possible source of the failure to upshift from 2nd? It looks like there is some wires broken going to a sensor on the transmission. Would doing a complete reset be advisable? If so what's the easiest way to do it?
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Saturday, February 11th, 2023 AT 2:39 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
Yes, that can cause it we can do a hard reset of the system which is easy by removing the negative side of the battery, with the cable loose from the negative side of the battery, hold it to the positive terminal for 1 minute this will discharge the memory capacitors in the BCM and PCM allowing the system to reboot. I would fix the wiring at the sensor first though. Can you upload an image of what you are seeing?
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Sunday, February 12th, 2023 AT 1:08 PM
Tiny
JEFF HERMAN
  • MEMBER
  • 437 POSTS
The truck runs, needed more gas. Lol going to drive in backyard for 10 minutes and see if it dies. If it doesn't, I'll take it on the road and check for upshift. First, I'll repair the wires and do the reset. With the 125A fuse in the power mirrors click for 5 seconds or so each time the key is turned on.
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Sunday, February 12th, 2023 AT 2:36 PM
Tiny
JEFF HERMAN
  • MEMBER
  • 437 POSTS
Drove around for 5 minutes, but it stalled. No fuel at rail. Then cranked a while and restarted with very low idle, stalled. Restarted after long crank, parked it. We're back into the 30's so that's all for now. Could just need more than 3 gallons in the tank to run but I don't think that's the issue. Thoughts?
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Monday, February 13th, 2023 AT 9:19 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
It sounds like the BCM is going out, I would try to get the engine running again and then tap on the BCM to see if the engine stalls here is the location, also let's do a CAN scan this guide will show you how (it is easy).

You can get a CAN scanner (Controller Area Network) from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is a list of CAN scanners starting at about $25.00 on Amazon:

https://amzn.to/3DBMlc7

Please check the images below and get back to me when you can.
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+1
Tuesday, February 14th, 2023 AT 12:13 PM
Tiny
JEFF HERMAN
  • MEMBER
  • 437 POSTS
I'm going to run it up the road later this afternoon was somebody is following me and see if it shifts. If it doesn't upshift, I've got a couple people making offers on it and I'll push it on down the road. If it does shift, then I'll work on figuring out the stalling issue. I got it for free and have about $100.00 in it. Thanks for the help and I'll let you know what happens. It also has at least one electrical quirk when the ignition key is inserted the power mirrors on both sides click for about 5 seconds and then stop?
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Tuesday, February 14th, 2023 AT 12:47 PM
Tiny
JEFF HERMAN
  • MEMBER
  • 437 POSTS
I should mention it stalls after it starts to warm up.
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Tuesday, February 14th, 2023 AT 12:48 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,512 POSTS
Okay, can you please start a new question about this issue, we like to keep the threads problem specific.

Please post your new question here, you must be logged in:

https://www.2carpros.com/questions/new

Cheers, Ken
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Tuesday, February 14th, 2023 AT 2:35 PM
Tiny
JEFF HERMAN
  • MEMBER
  • 437 POSTS
Trailblazer still didn't upshift and stalled. Wouldn't restart.
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Tuesday, February 14th, 2023 AT 7:29 PM

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