07 trailblazer idle relearn crankshaft relearn

[warriorpluto]

An 2007 trailblazer I'm having an issue with. It needs idle reset and crankshaft relearn My friend bought it from an auction. When I looked under the hood the PCM and throttle body had been replaced with brand new from previous owner. I knew this would be a problem. Previous mechanics also went through the Underwood wiring. I flashed the computer and still no change. There is an aftermarket radio installed but I removed the fuse. I have an code for the air pump as well. It has a bad misfire seems like. I can't get it to idle relearn to do an crankshaft relearn. May be the wiring some where because now another throttle body code has come up alongside the idle relearn. Also is this an factory plug?

 

[warriorpluto]

Here is an list of codes. They come right back instantly after clearing them

 

[mrrsm]

THAT Black Plastic Plug is the Central Ground Junction Point for the Class 2 Network System (Single Wire Network Ground)



@MAY03LT Covers this quite nicely on the importance of this G201 - SP201 (Splice Pack)

The rest of these issues may be Answered over HERE:

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gmtnation.com

 

[TJBaker57]

Also is this an factory plug?

That looks like SP201 & G201. Splice Point 201 and Ground 201. Yes, factory wiring. For vehicles in wet climates it can be a troublepoint as rust builds up under that bolt which secures it to chassis ground.

 

[TJBaker57]

I flashed the computer and still no change

Can you clarify this? Do you mean you updated the PCM calibration with a Tech 2 or similar?

 

[TJBaker57]

THAT Black Plastic Plug is the Central Ground Junction Point for the Class 2 Network System (Single Wire Network Ground)

A clarification here...

SP201/G201 is a major ground point for many in dash systems, including the HVAC module. However, its only connection to the Class 2 data system is to provide a ground point for a scantool.

It is not at all needed for the Class 2 network to function normally.

Without a scantool plugged into the data link connector that wire from G201 to the DLC (data link connector) goes no further. That ground wire from SP/G201 to the DLC is solely to provide a ground for a scantool.

Now then, for a scantool, at the DLC there is a second ground wire and that goes to G102, on the inner fender, under the hood near the fuseblock.

The scanners I have used join both grounds together at the DLC so either one can possibly provide a ground path for a scantool.

 

[mrrsm]

A Related, Comprehensive "On Topic" Article regarding Ground Splice Packs:

the "ground problem" and 355 "Splice...

www.355nation.net

 

[warriorpluto]

A clarification here...

SP201/G201 is a major ground point for many in dash systems, including the HVAC module. However, its only connection to the Class 2 data system is to provide a ground point for a scantool.

It is not at all needed for the Class 2 network to function normally.

Without a scantool plugged into the data link connector that wire from G201 to the DLC (data link connector) goes no further. That ground wire from SP/G201 to the DLC is solely to provide a ground for a scantool.

Now then, for a scantool, at the DLC there is a second ground wire and that goes to G102, on the inner fender, under the hood near the fuseblock.

The scanners I have used join both grounds together at the DLC so either one can possibly provide a ground path for a scantool.

Thanks for the explanation. I thought it was an aftermarket connection.