2003 Cadillac CTS 3.2 V6 automatic with wiring problems at the MAF and the ECM grounds- P0103 P0118

The car is running ok but there are wiring problems on the mass air flow sensor (MAF) and I am trying to verify the wiring integrity but need:
Pin-out for connector 1 (C1) at the Powertrain Control Module (PCM).  I need the circuit for pin 39 at this connector.  I also need to verify that MAF Pin 4 (labeled low reference on a wiring diagram I saw) is normally at 5 volts as I am measuring, and not supposed to be at ground voltage on this tan wire. 

In 2022 I was on this forum and got this car running but I had to cut (near the PCM) the tan wire to C1, Pin 39 and ground it to the engine block in order for the car to start.  I want to fix the problems with the ground to the MAF and figure out the circuit for the tan wire I cut. 

Attachments:  The second image shows the MAF/IAT sensor first unplugged (low readings), then plugged in and reads just over 4 g/s of air into the engine

Marti 

Here is the topic from when I first got this car running again ( Vegas JAK helped me then):   2003 Cadillac CTS with high voltage on the 5 v reference line2 was created by M arti

I also need to verify that MAF Pin 4 (labeled low reference on a wiring diagram I saw) is normally at 5 volts as I am measuring, and not supposed to be at ground voltage on this tan wire.

LOW REF should be GROUND.

 

 

I measure 5 v on the tan wire at MAF pin4 and get Diag code P0103 high voltage on the MAF signal line. Do I try short to ground ( short to tan pin 3) on pin 4 MAF to see if the code changes to low voltage?

I am assuming that you are checking the voltage with the MAF Sensor connected.

Disconnect the sensor and recheck the voltage. Do you still have 5 volts? If not, I would look for an open in the low ref wire between the sensor connector and the PCM.

Once you verify that pin 4 is not shorted to power, it would be safe to short pin 3 to pin 4.