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VGT position sensor, blink code 4-5 (low voltgae)

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I have a 2007 Mack Aset AC427 engine I'm having issues with. I'm using Mack's PTT software that is installed on my laptop.

I have blink code 4-5 (low voltage) popping up (VGT position sensor) and also it wont allow me to calibrate the turbo either. It says "Value outside permitted range" when trying to calibrate.

I went into my MacK Diagnostic manual and followed all the different steps for the blink code 4-5.

I went to the require pins and check ohms and voltage, I'm getting .01 volts off  the harness going to the  position sensor connector and also off the ECM pin that goes to the VGT position sensor. 

I cleaned the grounds on the main engine harness. I have two different ECM's laying around that I swap in and out . I used a different VGT control valve.

Just now I replaced the complete engine harness and the blink code 4-5 is still coming up. I have two VGT position sensors laying around that I tried as well.

I verified that air is coming out of the VGT control valve and ran air through the steel air line too, but I didn't gauge the air coming out of VGT control valve going to the VGT actuator.

I have no major air leaks, I do have the ATC & ABS light intermitting coming on.  

I used Macks' PTT software, Mack's shop manual and my imagination. I'm not sure what else to try besides it might be the actuator on the turbo?

If anyone can point me in the right direction I would appreciate it, thank you. 




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Shoot air directly into actuator and see if arm on turbo goes down. Only apply 30-40 pounds as not to blow diaphragm. There is instructions on manually adjusting actuator rod on a VGT turbo but I can't attach the bulletin at this time

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