Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
If you have 120 ohms across 6 and 14, one of the pair of resistors or wiring in one direction is open circuit.
I'll come back to you soon with some more info and a circuit diagram.
Can you leave your meter across 6 and 14, then disconnect X1 at the ECM.
If the 120 stays on the meter, the other direction is ok, and the fault is towards ECM. Vice Versa for if you lose the 120 ohms on your meter when you disconnect the ECM.
I'm glad you found that end, it shows on GM SI as after the Trailer Brake Control Module.
Can you see the wire colours at that point, should be TAN and TAN/WHITE.
Can you then measure the resistor you took off, hopefully open circuit.
If it reads 120 ohms, then place a short across the pins in place of the resistor.
Go back to 6 and 14. Technically it should be read a short now.
So either the resistor is open or or one wire from the ALDL 6,14 to the back of the vehicle is open circuit.
Ok, the rear resistor is fine.
Leave it off, and measure at 6 and 14.
If it reads open circuit, you were looking at the rear one only earlier from 6 and 14, meaning towards the front is open.
With the rear one off, if you are still 120 at 6 and 14, the front is fine.
The ECM resistor is non-serviceable.
I can't do phone call request, sorry.
But you proved all forward of the ALDL to the ECM is fine.
Your rear resistor is also fine.
The pair going to the back has an open on one wire of the the pair.
You can prove this with your meter, one leg of the meter in 6 the other leg to either wire at the back should see Zero ohms on one wire.
Same for 14, zero ohms on the other wire.
Can you now measure these two wires?
How did you go with the continuity test?
I hope my advice has been of assistance to you.