2015 Chevy Cruze Diesel Cooling Fan Always on No Engine Codes.

2015 CRUZE diesel runs the fan constantly even with the key off! I have no codes other than some TPMS Stuff. The car was in a wreck and reassembled by the customer.... Has had this problem ever since. I have power and ground at the fan but no signal.... I'm supposed to have a 12v square wave on the signal wire, correct? is there a relay inside the cooling fan module on these?
Thanks in advance for any help,
Elijah,
2nd Mile Repair

Thanks for the diagram... I Have No Signal coming from the PCM Through the black/Wht wire. My Wire is intact. Does No Voltage=Full Speed? Or should I suspect my PCM.

I can't find any information about the PWM signal. But, I would be more inclined to blame the fan control module. Do you have a scan tool to see if the PCM is requesting fan operation? Do you have any DTC's? Do you have a signal generator that you can use to induce a signal to the control module?

The scan tool shows the fan motor 11% on.... when I command it via bi-directional controls, nothing changes in the speed. However, with the fan unplugged, the voltage moves when commanded by the scanner. As soon as the fan/module are plugged in, the voltage drops back to zero on the signal line. I don't have a signal generator.... can you recommend a good one?

Also, there are some TPMS dtcs, but nothing in the ECM section.

Eli wrote:

The scan tool shows the fan motor 11% on.... when I command it via bi-directional controls, nothing changes in the speed. However, with the fan unplugged, the voltage moves when commanded by the scanner. As soon as the fan/module are plugged in, the voltage drops back to zero on the signal line.

Your problem is the fan/module.

Your right! The customer installed the gasser fan…. So it doesn’t even have the right components to be a PWM fan!
Thank you much!