So, to recap, the pump pumps and it's controllable with a diagnostic tool. You've tried putting a 500 ohm resistor in place of the temp sensor and it bumps the indicated temp to 300F and still no pump. Presumably by now you've also checked to make sure there's nothing blocking the air flow to the cooler, and that the cooler gets warm if you cycle the pump with warm fluid in the diff.
I'm traveling today but I'll take a look tomorrow when I'm home to see what the service manual says about this stuff.
It sounds like a switch to start the pump is your best option for now - put an extra wire with a light to show on/off - if the ECU actually starts it up, you'll know.
I'm traveling today but I'll take a look tomorrow when I'm home to see what the service manual says about this stuff.
It sounds like a switch to start the pump is your best option for now - put an extra wire with a light to show on/off - if the ECU actually starts it up, you'll know.