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I measured fron negative on sevcon just now. I have 48.66 volts top and bottom. The bottom drops if I press the accelerator
On the new solenoid, what does the top measure when the bottom is 24 volts?
Measure on the the stud, not the cable connector:

25719
 

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It is in the picture that I posted. You said that you replaced it.
The contactor has a solenoid that when energized closes the contacts to apply power to the motor controller.
People tend to refer to it as the solenoid or the contactor.
It is labeled contactor in the service manual:
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48 volts no drop on top. Yes that's what I replaced
Get some long leads for your meter and clip one on ground and the other on B+ on the sevcon
Put seat back on and turn on
You should have a min of 48 vdc and should not drop when u try to drive

If voltage drops and all cables are clean
And tight sounds like time for new batteries and cables
 

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The contactor is the device directly behind the main sevcon motor controller. It has two large studs (approx 5/16) one side goes to the + on the Sevcon motor controller, the other to the + on the battery pack. These have the main contacts to turn on the power to the Sevcon. . and two small screw screws with push on connectors, These are controlled by the Sevcon and operate the internal coil that moves the main contacts. The contact poles inside the contactor get corroded and deposits on them and then do not make proper contact. The controller sees a proper voltage and so turns on, but as you put on power the crud on the contact poles breaks down and the voltage drops. Then you get the fault. The units are riveted together and even if you get them apart its difficult to do a lasting repair. Is a replacement job. If you are still getting a voltage drop across the main contactor, ie 48v on the battery side and 24 the other when operated, then thats a contactor fault. Even if its new. But it does sound like a possible battery pack fault, and there you need to measure and note each of the 12v battery voltages at rest and as they fail. A lot of repeating to get a decent set of results but then you can see which batteries are at fault. Its then a decision to replace the pack or individual batteries. Its best to replace as a set. Otherwise once they start to fail you will continually be replacing one battery at a time, and never have much time with a decent working machine.
 

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Discussion Starter · #28 ·
I replaced the contactor before renewing the batteries. I charged each battery separately. That seemed to work. But a couple of trips it started all over again. So I replaced all batteries, changed speed sensor, changed FNR switch, changed charging indicator, changed dash indicator. Still can't figure it out. I ordered a new LMH switch just to see. My voltage drops from 50 to 27 when you try to accelerate. Could It be the pedal sensor?
 

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I replaced the contactor before renewing the batteries. I charged each battery separately. That seemed to work. But a couple of trips it started all over again. So I replaced all batteries, changed speed sensor, changed FNR switch, changed charging indicator, changed dash indicator. Still can't figure it out. I ordered a new LMH switch just to see. My voltage drops from 50 to 27 when you try to accelerate. Could It be the pedal sensor?
I read through the thread .. is your voltage still 50V at the top of the solenoid and 27V at the bottom of the solenoid when you are under load?

In my opinion, the pedal sensor is not the problem. The pedal sensor is what 'asks' for the speed. It can't drop the voltage of your pack. That is done by the controller trying to accelerate and the pack not supplying the current that the controller wants to use. Likely because the voltage is dropping across the contactor

Did you clean up the cable ends when you replaced the contactor? The cable ends get some corrosion ... and this can interfere with the current flow from your pack to the controller.
Take the contactor cables off, one at a time. Use a wire brush or emery cloth to knock the corrosion off the connector face, where it sits against the contactor lug. Put it back on and torque it down (don't break off the bolt though). Repeat for the other connection on the contactor. Test it and see if the problem went away

If not ....

THIS NEXT PART TAKES YOUR KEY SWITCH OUT OF THE CONTROL CIRCUIT!! THERE WILL BE A SPARK AS YOU CONNECT! MAYBE PUT THE POLARIS ON JACK STANDS FIRST!

My next step - if it was my Ranger - would be to move the cable from the bottom of the contactor to the top of the contactor (bypassing the contactor) to see if this solves your problem. Perhaps you got a dud for your new contactor? If you already cleaned up both cable connections above, you still need to clean the 'top' of the top connector, where the bottom cable will touch it. As before, use a wire brush or emery cloth to knock the corrosion off before bolting them together on the top post.

After that is done, and you have obviously verified that the polaris is not trying to move, you can try accelerating while it can't move around and see if you still see the problem. Or you can take it off the jack stands and go for a test drive.

Anyone want to chime in on whether this should be OK for a test? I have not tried this myself .. but it should be the same as turning the key to ON .. right?
 

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Discussion Starter · #30 ·
I read through the thread .. is your voltage still 50V at the top of the solenoid and 27V at the bottom of the solenoid when you are under load?

In my opinion, the pedal sensor is not the problem. The pedal sensor is what 'asks' for the speed. It can't drop the voltage of your pack. That is done by the controller trying to accelerate and the pack not supplying the current that the controller wants to use. Likely because the voltage is dropping across the contactor

Did you clean up the cable ends when you replaced the contactor? The cable ends get some corrosion ... and this can interfere with the current flow from your pack to the controller.
Take the contactor cables off, one at a time. Use a wire brush or emery cloth to knock the corrosion off the connector face, where it sits against the contactor lug. Put it back on and torque it down (don't break off the bolt though). Repeat for the other connection on the contactor. Test it and see if the problem went away

If not ....

THIS NEXT PART TAKES YOUR KEY SWITCH OUT OF THE CONTROL CIRCUIT!! THERE WILL BE A SPARK AS YOU CONNECT! MAYBE PUT THE POLARIS ON JACK STANDS FIRST!

My next step - if it was my Ranger - would be to move the cable from the bottom of the contactor to the top of the contactor (bypassing the contactor) to see if this solves your problem. Perhaps you got a dud for your new contactor? If you already cleaned up both cable connections above, you still need to clean the 'top' of the top connector, where the bottom cable will touch it. As before, use a wire brush or emery cloth to knock the corrosion off before bolting them together on the top post.

After that is done, and you have obviously verified that the polaris is not trying to move, you can try accelerating while it can't move around and see if you still see the problem. Or you can take it off the jack stands and go for a test drive.

Anyone want to chime in on whether this should be OK for a test? I have not tried this myself .. but it should be the same as turning the key to ON .. right?
Did everything except last step by putting wire from bottom of contactor to the top. Need more input on this. I think you right about a lemon contactor. 195.00 his hard to swallow. Is there a aftermarket cheaper?
 

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Discussion Starter · #31 ·
Ok, I changed the contactor again with aftermarket. Still no go. Only creaps a couple of inches. Stops, flashed 11 times, service tool comes on.
 

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Ok, I changed the contactor again with aftermarket. Still no go. Only creaps a couple of inches. Stops, flashed 11 times, service tool comes on.
So the contactor is not bad .. but you still see a voltage drop of about 1/2 your pack voltage from the top connector to the bottom? That's pretty strange!

Are you up for jacking up your ranger, moving the bottom contactor wire to the top contactor wire?
 

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Discussion Starter · #33 ·
So the contactor is not bad .. but you still see a voltage drop of about 1/2 your pack voltage from the top connector to the bottom? That's pretty strange!

Are you up for jacking up your ranger, moving the bottom contactor wire to the top contactor wire?
I'll try that this pm
 

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What you describe sounds like a faulty motor speed sensor. Is the speed sensor that you replaced in the back of the motor or does your have the sensor inside the motor? (Bearing speed sensor)
 

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Discussion Starter · #35 ·
What you describe sounds like a faulty motor speed sensor. Is the speed sensor that you replaced in the back of the motor or does your have the sensor inside the motor? (Bearing speed sensor)
I changed the sensor in the front on the gear housing
 

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That’s not the one. It’s in the motor. If you want you can call me and I will try to help. Lou217 430-3101
 

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Discussion Starter · #37 ·

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Anytime. I will be on the road to Chicago. If your speed sensor in the back of the motor you are in luck, if it’s inside the motor it’s a little more complicated
 
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