A little backstory to bring the current issue into perspective. As the title states I have an 03 330 magnum 4x4. Ive had it since it was new and it has been a great machine all these years. Last summer while spraying roundup, the ECM burned up, literally. It partially melted. I didnt know what the matter was, it just wouldnt crank and I didnt have time to mess with it so I took it to a ATV mechanic I was referred to. He had a heck of a time finding a new unit. He was told by Polaris that they didnt make that specific unit any more and that he was SOL finding one. He called all around and finally found one that would supposedly work. It did work but with the new unit in, the AWD doesnt work now. It did with the old unit tho, I know that for a fact.

There is 12V going to the AWD switch via the black wire at the top of the plug but nothing coming out of the other four wires (gray, gray/white strip, brown, brown/white stripe) with the switch in either position.

My question(s)...

-Does the ECU in any way control the AWD?
-Could the AWD switch have been burned up in some way when the stock ECU burned and I just need a new switch?
-Three of the wires coming out of the switch (cant remember which three right now) go to the front diff, but turn into 2 wires at a plug a few inches up from where they enter the diff. Where does the other wire go? Ive searched but I cannot find a good explanation or schematic anywhere on the web.

Thanks in advance
Andrew

 

Don't know why the mechanic had trouble finding the ecm as there are several listed on ebay among other places. 4010944 Polaris | eBay If your machine called for the 4010684 ecm for the non speedo model,then yes they are hard to find..
The ecm has three main functions:A battery protection circuit (allows power to the left hand control switch for lights,etc) power to the ignition switch,dash lights. A regulator/rectifier,and temperature controller(fan operation and hot light). These three main functions plus solid state circuit breakers for the protection of wiring and modules. The awd circuit doesn't go through the ecm although power for all electronics does. If you have voltage to the awd switch,voltage at the hot wire at the front diff,then possible it's just a ground problem on the brown/white wire that many machines have had in the past with the electronic speedo that pass the ground path through the speedo to complete the circuit for awd to engage.Plus here's some more on the speedo and how it shows gear position. It must show the correct gear range on the speedo,either high or low gear or awd can't power up to engage.

Again if you have 12 volts to the main power wire at the the awd switch,gear position is displayed properly,regrounding the brown/white wire from the speedo harness to a common brown(ground) or frame ground might complete the path for the awd to engage and bypasses the speedo. Too many paths for this small ground wire to go through(the awd switch,then the speedo,then to the front diff) and easy for it to lose ground path along the way. And yes,it's possible for the awd control switch itself to have been shorted out when the ecm burnt up.IF you don't have the speedo (FB model) just jumper the brown/white to brown or frame ground..If regrounding doesn't help,you might have to replace the throttle control. If this doesn't help,the manual should be able to give you more info and checks.
2003 Polaris Magnum 330 Service Manual PDF Download

 

Thanks a lot for the reply and good information. Let me start off by clarifying that I have the non speedo model.

I forgot to mention this in the original post but I ohmed out the switch from the power wire pin to the other four pins with the switch on and off but none of them had an open circuit in any position. This is what led me to believe the switch itself may be faulty.

Also, the more I think about it and that you mention grounding issues, it is very possible the mechanic just didn't rehook up a ground when he was reassembling everything. I will have to go back over everything and see if there could be a loose connection or something.

Lastly, at no time in either switch position is there any power on either wire going into the front differential.

Thanks
Andrew

 

Even if all wiring appears to be connected,no loose wiring,but still no awd,I'd jumper the brown/white wire to another ground position and see if that helps. Hope it's something simple.

 

Did you resolve the issue? My magnum did the same thing after switching the ECM. The old ECM kicks on the AWD with no problem. Did the grounding work?