Duramax Diesels Forum Truck of the Week
  #1  
Old 05-20-2017, 09:32 PM
Extended-lbz Extended-lbz is offline
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Default Lb7 anyway to reset ECM?

My truck started idling around 800rpm, tons of engine noise and the transmission started acting really weird and aggressive. After some research I found that bad thermostats would cause this and I noticed my ECT was really low and my temp gauge was all sporadic. So changed the thermostats now it comes up to temp but I cannot get the pilot injection to come back on and it still is idling high and the trans is still being stubborn. I am getting a ghost code and my cheap autozone scanner will not pull the code, even when the CEL is on. I tryed autozone and their scanner will not pull the code either. Is there anyway for me to reset the ECM? Local GM garage wants like $120 just to hookup to it and they are booked 2 weeks out. I have tryed disconnecting the neg terminals and let the truck sit for 2 hours, no change the CEL still comes and goes but scanner will not pull the code.

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  #2  
Old 05-21-2017, 05:00 PM
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THEFERMANATOR THEFERMANATOR is offline
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Check your coolant temp sensor. If it goes bad, the ecm will think the engine is at the wrong temp, and do everything you describe. I normally replace the coolant temp sensor with an ac delco whenever one is in question because they're cheap(about $15 from amazon), and can be so sporadic it makes it difficult to catch one acting up sometimes. With so many systems using its input, it's mot worth chancing any problems with it.
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Old 05-21-2017, 06:36 PM
Extended-lbz Extended-lbz is offline
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Quote:
Originally Posted by THEFERMANATOR View Post
Check your coolant temp sensor. If it goes bad, the ecm will think the engine is at the wrong temp, and do everything you describe. I normally replace the coolant temp sensor with an ac delco whenever one is in question because they're cheap(about $15 from amazon), and can be so sporadic it makes it difficult to catch one acting up sometimes. With so many systems using its input, it's mot worth chancing any problems with it.
For $15 I will give it a shot, this truck has been cursed

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Old 05-21-2017, 06:40 PM
Extended-lbz Extended-lbz is offline
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Quote:
Originally Posted by THEFERMANATOR View Post
Check your coolant temp sensor. If it goes bad, the ecm will think the engine is at the wrong temp, and do everything you describe. I normally replace the coolant temp sensor with an ac delco whenever one is in question because they're cheap(about $15 from amazon), and can be so sporadic it makes it difficult to catch one acting up sometimes. With so many systems using its input, it's mot worth chancing any problems with it.
Can you send me a link to said sensor and im assuming the coolant temp sensor on the water pipe off the tstat housing correct?

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Old 05-21-2017, 10:10 PM
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2004LB7 2004LB7 is offline
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This might be what you are looking for

http://m.autozone.com/engine-managem...8589?location=
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Old 05-22-2017, 03:40 AM
Extended-lbz Extended-lbz is offline
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Quote:
Originally Posted by 2004LB7 View Post
This might be what you are looking for

http://m.autozone.com/engine-managem...8589?location=
I found this

https://www.amazon.com/gp/aw/d/B000C...KIKX0DER&psc=1

But it says use mating connected PT1798, but it looks as if itd be a direct replacement

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Old 05-25-2017, 10:37 PM
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Thats the one. Just put one in for my neighbor about a month ago in his GM using that very one.
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Old 05-25-2017, 10:52 PM
Extended-lbz Extended-lbz is offline
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Quote:
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Thats the one. Just put one in for my neighbor about a month ago in his GM using that very one.
Awsome thanks, Mine will be in tomorrow so I will swap it out and see what it does. Im going to drop the truck off at All in truck performance when I head back to NY and have a 02 OS flashed in with a single tune so hoping that will clear up the other issues I have been having

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  #9  
Old 05-26-2017, 09:51 PM
Extended-lbz Extended-lbz is offline
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Well installed new thermostats and a new ECT sensor and un hooked the batteries for about an hour.. still high idle and the trans is still being wacky

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Old 05-26-2017, 11:33 PM
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Need to get a tech 2 on that thing, check ALL the sensors, could be a junk ecm or bad wiring.

Sounds like a bad ambient air temp sensor, but mine never made the truck idle high.
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Old 05-26-2017, 11:36 PM
Extended-lbz Extended-lbz is offline
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Quote:
Originally Posted by WVRigrat05 View Post
Need to get a tech 2 on that thing, check ALL the sensors, could be a junk ecm or bad wiring.

Sounds like a bad ambient air temp sensor, but mine never made the truck idle high.
Its getting dropped off at all in truck performance here in TX in 3 days hopefully its a simple fix Im out of element and no resources as I live in NY. They are going to flash in a 02 OS system and hopefully can diagnose the truck

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Old 05-27-2017, 12:15 AM
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It's simple I'm sure, but without a good scanner you're pissing time and money away.
Everyone something went on my truck I was 3-8 hours from the house, swear they know you're out of town.
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Old 05-27-2017, 12:58 AM
Extended-lbz Extended-lbz is offline
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Quote:
Originally Posted by WVRigrat05 View Post
It's simple I'm sure, but without a good scanner you're pissing time and money away.
Everyone something went on my truck I was 3-8 hours from the house, swear they know you're out of town.
Haha yessir, I have access to efi live and a insight cts2 at home of course. Just didnt think id need it

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Old 04-15-2018, 03:32 PM
nwodiesel nwodiesel is offline
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Quote:
Originally Posted by Extended-lbz View Post
My truck started idling around 800rpm, tons of engine noise and the transmission started acting really weird and aggressive. After some research I found that bad thermostats would cause this and I noticed my ECT was really low and my temp gauge was all sporadic. So changed the thermostats now it comes up to temp but I cannot get the pilot injection to come back on and it still is idling high and the trans is still being stubborn. I am getting a ghost code and my cheap autozone scanner will not pull the code, even when the CEL is on. I tryed autozone and their scanner will not pull the code either. Is there anyway for me to reset the ECM? Local GM garage wants like $120 just to hookup to it and they are booked 2 weeks out. I have tryed disconnecting the neg terminals and let the truck sit for 2 hours, no change the CEL still comes and goes but scanner will not pull the code.

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I know this is an old post but this is exactly whats going on with my lb7. Did changing the sensor cure it cure it? Thanks in advance. Any help appreciated.Cory
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