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2004 Chevy Trailblazer Failed emission and 12 DTC codes

Tiny
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  • 2004 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 91,000 MILES
I currently failed the state emission test they said the computer had an error code pointing to an emission problem. I took it to a shop where they came up with the following codes;
P0014 - Ex. Cam position
P0112 - IAT Sensor CKT Low Voltage
P0117 - ECT Sensor CKT Low Voltage
P0123 - TP Sensor CKT High Voltage
P0128 - Engine Coolant below T-Stat Regulated Temp
P0131 - H02S CKT Low Voltage (B1-S1)
P0133 - HO2S Slow Response (B1-S1)
P0138 - HO2S CKT High Volt (B1-S2)
P0621 - Generator L-Terminal CKT
P1133 - HO2S Insufficient Switching (B1-S1)
P1574 - Stoplamp Switch CKT
P1680 - Control Module Accelerator Pedal Position System performance

PCM sending 5V signal to L-Circuit on Alternator
Alternator has a shorted regulator causing a drop in V to 1.8
There is a knocking in the back which are the dampers for the A/C that seem to have lost their calibration and try to go beyond the stop.

We replaced the alternator and belt about a year and a half ago when we broke down (small shop in the middle of nowhere)
The shop wants to replace the alternator, PCM, Thermostat, Exhaust Cam Actuator and serpentine belt.
I don't think I need all of those replaced.
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Saturday, January 24th, 2009 AT 8:35 AM

11 Replies

Tiny
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Slam on the brakes!

I wouldn't jump to all of the conclusions for sure.

Are these history codes or all current?

What specific codes came up during the inspection. In NY anyways, you get a print out of the failing codes.
The alternater may be the whole ball of wax on some of those. If the battery is not charged fully and being charged fully you can get some weird things happening. That alternater may have a lifetime warranty depending on the brand.
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Saturday, January 24th, 2009 AT 9:00 AM
Tiny
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These codes are current.
The emission only stated P0128 - Manufacturer specific codee.
The other codes came from the repair shop we took it to.

Thanks
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Saturday, January 24th, 2009 AT 9:22 AM
Tiny
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Good.

Put a thermostat in it. The coolant is not coming to temperature as it should, that will likely solve that code and probably others. THis should get you through inspection for emissions.

You know the alternater is bad, so that would be the also a warranted repair.
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Saturday, January 24th, 2009 AT 9:30 AM
Tiny
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I replaced the alternator and the thermostat and passed emissions! The truck has been running great then about a month ago the headlights started to flicker as the truck was idle. I thought maybe just getting used to the new alternator.
Yesterday my wife called and said that the instrument cluster was completely out and so was the AC and power windows. She made it home and it wouldn't turn on, seemed like dead battery.
Last night I went out to check on it, the truck turned on instruments worked, except battery showed low and the battery light turned on.
Do I need to replace battery, alternator and PCM this time?
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Friday, June 26th, 2009 AT 5:22 AM
Tiny
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Need to check the alternator. Some reman alternaters are built poorly and can fail prematurleu or be bad off the shelf. That is where I would start.
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Friday, June 26th, 2009 AT 2:35 PM
Tiny
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OK I replaced the battery and the alternator, truck fired up and sounded great! Went for a drive seemed ok. Turned it off and then went to run some errands about an hour into the drive it stopped dead again. After turning it off for a few minutes we were able to start it back up and drive home.
What is going on?
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Friday, June 26th, 2009 AT 2:40 PM
Tiny
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I meant "check" them, not replace them.

https://www.2carpros.com/how_to/battery.htm

When it did not start, did it still crank, or did it do nothing when the key was turned?
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Saturday, June 27th, 2009 AT 5:24 AM
Tiny
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The battery was low and the alternator tested bad. I took both into the parts store and they replaced both (under warranty still). When the car turned off it was completely dead, wouldn't turn over nothing worked at all. After a few minutes it turned over the seat belt light stayed on as well as the check engine light and we heard a chime al the way home like the door was open with the key in the ignition.

Thanks
Also the sound in the back are still going, it seems like the dampers in the back that control the temp and the vents are not calibrated they bang over and over for about 2 minutes then stop. I took the panel off and removed the controllers and they move freely but it seems like beyond what the dampers should be able to go.
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Saturday, June 27th, 2009 AT 5:55 AM
Tiny
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What brand of alternater is this?
Sounds like a typical problem child one. I have seen them and now only use the Napa premium or the USA brand. I lost faith in most others.
IF it tests bad again, I would start asking about getting paid for having to replace it again.

The battery will recover after a complete drain down, and that sounds like what is happening. Alt not charging, draining the battery.

A/C may need recalibration.
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Saturday, June 27th, 2009 AT 6:41 AM
Tiny
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It's a Remy remanufactured alternator. The guy at the part store actually gave me an alternator that had been returned by someone else. Swapped it out again and truck seems to be running smooth once again.
If it happens again I will go for the NAPA new alternator. How do I calibrate the A/C?
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Saturday, June 27th, 2009 AT 10:19 PM
Tiny
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The only way I am aware to recalibrate is to do it with a hand held diagnostic computer that has that capability.

Can you change the alt in your sleep now? LOL.
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Sunday, June 28th, 2009 AT 8:42 AM

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