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Discussion Starter #1
I have a 05 canyon and I had the check engine light come on. Went and had the code ran and it returned p2771 code. The code definition is four wheel drive low switch circuit malfunction. What I am confused about is that I have a 2 wheel drive automatic vehicle. Anyone know why I would get a code referring to something on a 4 wheel drive?
 

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Re: lost

Sounds like you have 2 clutch packs applying or a band not letting go or a sprag not letting loose. Pull the pan and look for metal.
 

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Discussion Starter #5
This is the correct code that it showed. The ecm was bad. They said it was from the aftermarket radio installed in the truck. They said that a New ecm was put in and still would not program until they removed the radio. Not sure how this messed up the ecm because everything was installed using proper wiring and plugs. Unless there is a different plug I need. I got one that said from 2000 and up. It has chime box and all that. I don't have on star or any bells and whistles. Plain truck with manual everything. Anyone heard anything about the radio issue now that the other one is resolved?
 

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This is the correct code that it showed. The ecm was bad. They said it was from the aftermarket radio installed in the truck. They said that a New ecm was put in and still would not program until they removed the radio. Not sure how this messed up the ecm because everything was installed using proper wiring and plugs. Unless there is a different plug I need. I got one that said from 2000 and up. It has chime box and all that. I don't have on star or any bells and whistles. Plain truck with manual everything. Anyone heard anything about the radio issue now that the other one is resolved?
There are several door chime modules that can cause PCM interference. The info is all in a thread here on which modules to use and which to stay away from.
 

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I just installed my new Pioneer HU in the truck this weekend and, other than the BCM going goofy for a day (e.g. no driver window & locks) all is well. I knew it would self-correct over time. Same as you...plain truck, but 4WD auto. My radio interface came from Crutchfield and I paid a tad more for better unit (Crux SOCGM-17) as I read here about the cheap/poor ones. Maybe get one & add...??
 

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Weird gremlin you got there.... Never had any issues with my Kenwood H.U.
Everything came from Crutchfield... But that is not the interface that came with mine..
I would contact them and be sure you are receiving the correct one... Hope you get it going !!!
 

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Discussion Starter #10
It's an automatic. And the head unit is a pioneer. I have installed stereos for myself and others for about 12 years now and this is the first time this has happened. I played $40 for the step down harness. I may just have to go old school and run my own wires. I am going to do a little research tonight while at work and try to figure it out.
 

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Do you know what brand harness was used? Do you have a factoy radio you can install?

The stereo is also the BUS system and sometimes causes problems with certain wiring configurations, as indicated above.

You need to definitely research how to wire it hot if you want to do that. No matter what you have done in the past 12 years, I bet this one is different (because it is). If you have the OEM radio, I'd start there. Going crazy cutting wires out and doing what you remember doing in the past won't necessarily solve your problems here.

Hate to blame this on a stereo wiring when there could be something much more wrong happening. Don't spend much time on the stereo.
 

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Discussion Starter #12
the harness was a schosche brand. the factory radio is back in now and there are no issues. I was not going to cut any wires, was just going to run my own power wires and speaker wires and just not use the factory wiring harness at all. I know this one is different, just odd that in all that time of doing this I have not had this issue. I have another vehicle that is a newer model and have had others and have not had this issue. I know they were not a canyon it just has me at a loss. have not had time to research yet but until I figure it out the factory is back in the dash for now.
 

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Well to be honest, I haven't not heard very many good things about the Scosche chimes retention modules.

I do not have any personal experience, but I asked if you knew which was installed for the specific reason - somewhat expecting that to be your answer.
 

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Discussion Starter #15
the thing is, now I am worried about putting any type of harness in the truck now because if it kills the ecm again I will have to pay for it. I'm not sure what else could cause this to happen. I want my stereo in but not sure if I want to chance it. I don't have a problem getting another kind that may be better. I'm just not sure if I will have the same problem again. I wonder if I try another one and it does it again, if I just remove the radio would it fix itself? what do you think?
 

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For what it's worth, the two preferred wire harnesses are

GMOS
GMRC

Once in a while one of those will fail, but only because they broke. Not fail such as they make other vehicle problems. It sounds very infrequent though.
I've had one for about 2.5 years I think. And most everybody who has aftermarket stereos use one of those products too.
 

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the thing is, now I am worried about putting any type of harness in the truck now because if it kills the ecm again I will have to pay for it. I'm not sure what else could cause this to happen. I want my stereo in but not sure if I want to chance it. I don't have a problem getting another kind that may be better. I'm just not sure if I will have the same problem again. I wonder if I try another one and it does it again, if I just remove the radio would it fix itself? what do you think?
I don't see any connection between the ECM (PCM in your truck), and the radio adapter. Now, if I was working in a "less than honest" shop and aware that aftermarket installations can cause problems with the electrical circuits, I would claim that the ECM was bad, replace it, and then "fix" the problem by removing the aftermarket radio.
 

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Discussion Starter #18
Well that's another thing. Don't think they would have made it up to get money since it was repaired at the dealer I bought it from and I did not pay for the repair. I had thought the same thing about them just saying it was the radio but since I paid for none of the cost on repair I'm still left wondering. I have also always used one brand or another for the wiring harness and never had the issue on anything else. I am going to try another harness I guess and hope for the best that it won't fry it again.
 

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The modules mess up the serial communication with the PCM because the door chime is run from the BCM which communicates directly with the PCM. The PCM might have been fine and it was just a short from the module and since they couldn't communicate with the PCM, they replaced it same thing happened so they looked elsewhere.

Metra GMOS-1 is what I had in my truck for a few years, the previous car I owned for 4 years, and in my current car for 2.
 

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Yeah, I was thinking something similar. Although the radio and the OEM chimes are under control of the BCM, it is over the Serial Data Bus, of which the PCM is a component. Anything that affects the Serial Data Bus can possibly affect the operation of any of the modules on the bus, without actually damaging them.
 
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