Looks like I am going to have to replace either the rectifier or stator on my 2010 Rancher 420. Going to test them tonight. With the engine running the multimeter reading drops to 12.5v even with the engine revved up and goes no higher. Looks like the rectifier is easy enough to replace but my question is...if it turns out to be the stator (hopefully not), how difficult is it to replace? Is it something I can do myself or will I need to take it to a mechanic?

 

Just found a service manual online and step 1 is remove engine. That's above my pay grade. I sure hope it's the rectifier.

 

Not sure if I have done a 420 stator, but I have never needed to remove the engine to replace it on 250, 350,400, 450 or 500 so would be surprised if you did need to remove the engine. Swinging arm yes, then you can get at the back end of the engine fairly easily.

Regarding a non charging alternator, 9 times out of 10 it is the voltage regulator, I tested a 420 on Wed, leaking current big time (about 10 amp) only fitted it in April. Put a new, non genuine regulator on, overcharging, (circa 16v) so am waiting for yet another cheap regulator that my boss insists on buying.

Test battery power to the regulator with a test lamp. I once fitted a new stator to a 500 only to find the fault was still on, turned out to be an internally corroded wire from battery to regulator, it gave 12v on a meter but wouldn't light a test lamp.

 

How would I do this test? I tested the 3 yellow wires last night and that checked out ok if I did it correctly. Planning on ordering a rectifier but would like to test it first.

 

Unplug the regulator and put the test lamp across the red and green connectors in the loom plug, the lamp should light brightly. The book may be right about removing the engine, earlier models had the alternator in a separate case behind the engine, the casting on the 420 contains the output shaft etc, which will make it harder to remove. RM Stator regulator fitted to the 420 I mentioned yesterday, we will see if that one lasts.

 

Thanks for the clarification. Picked up a tester light this weekend. Going to test it out tonight hopefully.

 

Conducted the test above and test light lit up so there is power from the battery. I will probably order a new regulator and hope that fixes the problem.