The other day, a service tech called and wanted to make sure that he was making a COMPLETE diagnostic of an ECM motor that was not working. He had checked out the motor with his GE TechMATE Pro and found the motor would not run. He had taken off the module and checked out the motor with both the “ohms” test to the shell and between “windings” and the motor was good (see ECM Motor Troubleshooting post Part 1). He knew he had a bad module.
But he also wanted to make sure the unit control board was good and sending the correct signals. He had the “decoder chart” for the pins that was on my troubleshooting post EXCEPT the 16 pin plug only had 12 wires in it. So he was lost but still wanted to make a complete diagnostic so he called me.
Believe it or not — I didn’t have the answer! It seems some manufactures have, over the years, modified the basic wiring to suit their particular application. So I made a few phone calls and found out a couple of things.
On motors using the 12 wire application instead of all 16 wires, the manufacturer was “doubling up” the duty of some of the connectors. Attached below is a chart showing how the pins were doubled up. We were still able to verify some of the pins like position 15 – “G” – with just the fan running and position 12 – “R” – as power to the module, so we were pretty sure the board was functioning properly.
After I had obtained this info, I passed it on to the tech and he finished his check out of the board when he went back with the new module for the motor. The board did turn out to be GOOD still .
Now, in the process of doing all this research, I learned one more thing: that some manufacturers REVERSE W1 and W2 in the plug and programming. Regal-Beloit uses a “standard” configuration for the plug but manufacturer’s can modify to suit their needs to a point. Attached is the Regal-Beloit chart showing their default pin positions.
Original pin position diagram from original post:
Note that position 2 is W2 and position 13 is W1 above but the Regal Beloit standard is position 2 is W/W1 and position 13 is EM/W2(EM = Emergency Heat). Note: the original chart in my post had it the opposite. This is another good reason to ALWAYS follow the manufacturer’s instructions/wiring diagrams as that original post had the chart taken from a York manual.
Well, today was a very good day for me because I LEARNED 2 new things! Hopefully, this post will help you further in your diagnostics. All of this came about because a CONSCIENCIOUS SERVICE TECH wanted to do a complete job. — My hat is off to him!
Thanks to the Regal-Beloit Dealer Tool Box site for the “default position” chart information above. Also — Thanks to Casey McConnaughy of York Tech Service for the 12/16 pin position information.