The 1947 - Present Chevrolet & GMC Truck Message Board Network

The 1947 - Present Chevrolet & GMC Truck Message Board Network (https://67-72chevytrucks.com/vboard/index.php)

- LSx Swaps (https://67-72chevytrucks.com/vboard/forumdisplay.php?f=206)

- - Voltage from pin 57 (https://67-72chevytrucks.com/vboard/showthread.php?t=808423)

Voltage from pin 57

E38 ECM and TCM from a 2008 avalanche at pin 57 I have 10v w/ key on and it fluctuates between 3.4 and 5.3 when running I thought it should be 5v all the time any help would be great

Re: Voltage from pin 57

Quote:

Originally Posted by nsb29 (Post 8765601)

E38 ECM and TCM from a 2008 avalanche at pin 57 I have 10v w/ key on and it fluctuates between 3.4 and 5.3 when running I thought it should be 5v all the time any help would be great

Are you referring to pin 57 on ECM connector 1 or connector 2?

Pin 57 on connector 1 is the VSS signal which is a 12v square wave. If you measure it with a voltage meter, it isn't going to tell you much. But it will vary with speed.

Pin 57 on connector 2 is the Bank 1 upstream O2 sensor. It's an analog signal that will vary with the AFR. It's not going to tell you much to probe that with a voltage meter, either.

Re: Voltage from pin 57

Pin 57 connector 1 being used for speedometer every thing was working fine and then became erratic and quite