I have a 2003 bayou and it does not charge the battery. Does anyone know how to test the voltage regulator before I spend 140 on a new one. I used a DMM and measured the voltage at the battery and it never goes above 12 volts. The longer I run the atv the lower the voltage goes. I checked all of the wires and they seem ok. Does anyone have a manual that tells how to test the regulator?

 

The voltage regulator's function is to change AC to DC and limit its output voltage to 14~14.5 VDC. You should check out the alternator output voltage. First disconnect the alternator output connector right next to the recoil pull start handle. There should be 2 yellow wires. Set your DMM to 250AVC range, connect + to one yellow leand and - to another yellow lead. Run the engine at about 4~4500 rpm (guess it is about 2/3 throttle open since 7000 is max) and see what the output is. If the reading is lower than 38VAC, either there is a break in the stator coil or the rotor magnet has gone bad.

 

I agree, it sounds like more of a stator problem then a reguator problem.
You should also be able to just ohm out the coils of the stator with the motor off. I dont have the specs handy, and the regulator can be checked as well, and a service manual will show how thats done. You basicly check the diodes for opens and shorts. If you dont have a service manual, try the local library, in the 629.2 area of non fiction. If it isnt there, then ask the libraian if she can get it from another branch. Almost all libraries , have at least one book covering the bayou.

 

The wires coming out of the engine by the pull start handle go all the way to the voltage regulator connector. There is no connector at the engine. There are six spade connectors going into the voltage regulator. I have checked all libraries in the Milwaukee county area and none have a manual that covers the 2003 bayou.

 

If you can't find a 3-pin/blade alternator connector at the engine side, you can do the same test at the voltage reg side. Disconnect the 6 pin connector at the reg. There should be 3 yellow wires (and other 3 should be BK/Y, Br & W), and measure the AC voltage 3 times since there are 3 sets of coils on the stator. What I means is you need to pair up 2 yellow wires 3 times in 3 different combination. Using pieces of masking tape, label the yellow wires, A, B & C to avoid a confusion. Then measure (A & B), (A & C), and (B & C). Each reading must be >= 38VAC.

 

I will do the voltage test on the stator tonight. If someone could tell me how to test the regulator and what to measure for that would be great. Thanks for all the help so far.

 

I checked voltage between each of the three wires and I have 60 VAC. On the regulator I can only get a resistance reading between two of the 6 pins. It is 30Kohms and they are not any of the three yellow wire terminals. Where do the other three wires on the harness goto? maybe one of them is broke?

 

Your stator seems alive.
W goes to (+) batt and there is a 20A fuse in between.
BK/Y goes to (-) batt.
Br goes to few lights.
Check the continuity of BK/Y and W wires.

 

Millerboy, if your charging coil is putting out plenty of voltage the regulator/rectifier is the only other thing that could keep the charging voltage going to the battery so low.

You can check it by testing the forward and reverse bias of the diodes. Your meter should have a diode symbol or audible continuity.
Disconnect the R/R. Find the spades on the R/R that connect to the three yellow wires the bk/y and white wires. Set your meter to the diode check setting. Hold the black meter lead to the spade the BK/Y wire connects to and with the red lead touch each of the spades(individually) the yellow wires connect to.
This is reverse bias for the ground side of the R/R. Your meter should read OL or OFL for all three spades(no continuity). If it measures any voltage the diodes are bad. Now swap the meter leads. Hold the red one to the ground side of the R/R and touch each yellow wire spade with the black lead. Here you should get a voltage reading(very small like .5VDC).
Do the same for the hot side of the R/R. Black meter lead to the white wire spade. red lead touch the three yellow wire spades(individually). Should get a voltage reading. Swap meter leads and do the same thing. Reading should be OL or OFL.

 

I did the check and had .5 volts on all three and OL the other way using the white wire spade, when I did the BK/y wire I had OL on two and .5 volts on the third, swapping the probes I had .5 volts on two and OL on one. It looks to me like a bad regulator. I ordered one yesterday so in a few days I will know. Thanks for all your help. I am also going to trace the other wires tonight. I have new chains and a new cycle country plow on there and cant use it. That stinks ecspecially since we are getting a few inches of snow today.