I did a write up on testing the 4wd system awhile ago. I copied it below.
Easy things first.
1. Fuses okay? Main and 4wd
2. Battery in good condition and charged
3. Main switch working (you replaced it so should be okay)
4. Test 4WD relay 1
5. Test 4WD relay 2
6. Test 4WD relay 3
7. Test handle bar 2WD/3WD/4WD switch
8. Test the gear motor
9. Check the wires and wiring connections of the 2WD/3WD/4WD system
10. Possible problem with front differential
11. Replace the meter assembly
Steps 4 and 5 - Testing relays 1 and 2. I think the relays are located under the seat on the 02 660's. A relay is a switch. It has two positions - one when it's not powered and one when it is. So for each relay you need to do 2 tests. Your relay will have 5 connectors.
Relays 1 and 2 look like an upside down T. Terminal 1 is at the top, down is terminal 5. Across the bottom left to right are terminals 4, 2, and 3.
Test 1 - Set your digital pocket tester to resistance testing 1 ohm. Connect the positive lead to terminal 1 and the negative lead to terminal 2. You should get resistance. I used a small piece of wire with a spade connector on it to get better access to the terminals on the relay.
Test 2 - You have to power the resistor to "flip the switch". So I made two pieces of wire with alligator clips on one end to attach to the battery and spade connectors on the other end to attach to the relay. Connect the positive battery wire to terminal 3. Connect the negative battery wire to terminal 4. Then take your pocket tester and connect the positive wire to terminal 1 and your negative wire to terminal 5. You should have continuity. I know, 4 wires in a small space make it hard to work with. Now you know why I made little jumper wires.
Do this for both relays.
Step 6 details - This is to test the 3rd relay switch. Like the other relays the switch has two positions one that is powered and one that it is not. It looks a little different than the other two.
Relay 3 is square shaped positioned with a little notch pointing out at the top and the top left and top right corners indented. In the top right corner is terminal 2. In the bottom right corner is terminal 1. In the bottom left corner is terminal 3. And in the top left corner is terminal 4.
To help with orientation, terminal 2 on the relay is connected to the yellow and black wire.
Test 1 - Set your digital pocket tester to resistance testing 1 ohm. Connect the positive lead to terminal 1 and the negative lead to terminal 2. You should get resistance.
Test 2 - You have to power the resistor to "flip the switch". Connect the positive battery wire to terminal 1. Connect the negative battery wire to terminal 2. Then take your pocket tester and connect the positive wire to terminal 3 and your negative wire to terminal 4. Your should have continuity.
Step 7 Details - Testing the handle bar 2WD/3WD/4WD switch. The switch has a few wires coming out of it. Trace the wires to the connector ("under the hood"). The connector should have 8 terminals.
Set your pocket tester to resistance 1 ohms.
The switch will have 3 settings - 2WD, 3WD, and 4WD. Set the switch to 2WD. Test between terminal positions 1&2, 1&5, and 2&5. They should have continuity. Test the other positions to make sure they do NOT have continuity - 1&3, 1&4, 1&6, 1&7, 1&8, 2&3, 2&4, 2&6, 2&7, 2&8, 3&4, 3&5, 3&6, 3&7, 3&8, 4&5, 4&6, 4&7, 4&8, 5&6, 5&7, 5&8, 6&7, 6&8, and 7&8.
Change to 3WD. Test between terminal positions 1&2 and 3&4. They should have continuity. Test the other positions to make sure they do NOT have continuity - 1&3, 1&4, 1&5, 1&6, 1&7, 1&8, 2&3, 2&4, 2&5, 2&6, 2&7, 2&8, 3&5, 3&6, 3&7, 3&8, 4&5, 4&6, 4&7, 4&8, 5&6, 5&7, 5&8, 6&7, 6&8, and 7&8.
Change to 4WD (Diff lock). Test between terminal positions 3&4, 5&6, and 7&8. They should have continuity. Test the other positions to make sure they do NOT have continuity - 1&2, 1&3, 1&4, 1&5, 1&6, 1&7, 1&8, 2&3, 2&4, 2&5, 2&6, 2&7, 2&8, 3&5, 3&6, 3&7, 3&8, 4&5, 4&6, 4&7, 4&8, 5&7, 5&8, 6&7, and 6&8.
If any of the tests fail to have continuity when they should or have continuity when they shouldn't then your handle bar switch is bad. I have had limited success taking the switch apart and cleaning the terminals. If you decide to do that, watch out for the flying little springs. When they land on the floor you can't find them! After cleaning then retest. If you still fail, then buy a new switch.
Step 8 Details - Testing the gear motor. First you need to make a little battery fuel cell. Connect 2 C size batteries end to end. Connect a negative and positive wire to the battery pack. I used the wires from my pocket tester and with the help of a little duct tape got them to stay in place. You may need someone to hold the battery pack together firmly to make sure current flows.
Disconnect the gear motor coupler, remove the gear motor from the front differential. You need to do 2 tests. First, connect your battery pack negative wire to terminal 1 on the gear motor and the positive wire to terminal 2 on the gear motor. The gear should turn counter-clockwise.
Test two is the reverse. Positive to position 1 on the gear motor and negative on terminal 2. The gear should turn clockwise.
If it doesn't work, then try to repair to repair the gear motor. I have taken it apart and tested the little drive motor directly. You can get the internal motor only on ebay. There is a little platform that reminded me of the old record players with the arm and needle on them. They can be cleaned up for good contact, but be careful.
Hook up the electrical coupler and change the handle bar selector switch between 2WD, 3WD, and 4WD making note that the gear is turning to it's proper position. All the way one way for 2WD, middle position for 3WD, and all the way the other way for 4WD. I put a tiny piece of duct tape on the end of the gear shaft so I could see which way it turns.
After you have confirmed that everything is turning correctly, select 2WD. Then disconnect the electrical coupler.
Inside the differential slide the bar all the way to the left (2WD position), then attach the gear motor. This is important. The slide in the differential AND the gear motor need to be both in the 2WD position.
Don't over tighten the bolts. Aluminum is very soft and the bolts strip easy.
It should work.
07 700 Grizzly
B-Line Control Suspension, Penland Exhaust, Power Commander III Fuel Optimizer, Dynatek CDI Controller, EPI Clutch kit, Rath Racing Front Sway Bar, EHS Air Box Mod, Thumb/Grip/Seat Warmers, Horn, Bottle holder, Grip Donuts, Warn 3k with remote and synthetic wire, Moose Hand Guards, Mud lights/ATR's/Outlaw Tires, ITP Rims, Tamarack Trunk, Fuel Pak, ATV Rocks Skid Plates, 2r Foot Pegs and Rails.
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