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Electric EZGO Electric EZ GO Marathon, Medalist, TXT and RXV. |
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04-21-2014, 10:34 PM | #1 |
Not Yet Wild
Join Date: Apr 2014
Posts: 6
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Possible bad resistor
Hello guys, I have an EZgo 2008 electric cart that has been moving very slow. Might be called "limp mode". I should say that the original problem was the cart just died. It would charge and when you pressed the pedal it would move like an inch then nothing. I changed the solenoid and it didn't seem to help. Cleaned up the batteries, changed a couple wires and now it moves but very slow. I have done the diagnostic thing and get 3-2 code (welded solenoid). I installed a new solenoid so I don't think that is correct. I did a little test by removing the resistor that is on the solenoid and the speed came back. I put the resistor back on and the speed leaves. Is this resistor bad? I have also been reading some very informative stuff on this forum and some suggest it might be the speed sensor or a bad wire. Any help is appreciated.
Thanks, Littledigger |
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04-22-2014, 12:08 AM | #2 |
Gone Wild
Join Date: Jan 2014
Location: South Georgia
Posts: 1,120
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Re: Possible bad resistor
Probably not the resistor. Do you have a voltmeter? You going to need one to troubleshoot this. Don't do too much trying to get the cart to move without the resistor connected or you will have a welded solenoid contact for sure. That resistor keeps the controller charged so when the solenoid energizes there is not a sudden high current arc on the contacts. Leave the resistor connected. Get your voltmeter out and myself or someone else will jump in and help you. First thing get started troubleshooting would be to measure the battery voltage on the big leads on the solenoid the resistor is connected to when the pedal is depressed.
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04-22-2014, 09:10 AM | #3 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: Possible bad resistor
Check the voltage on J1 Pins 4 & 5. Both should be FULL battery pack voltage.
The way the controller checks for welded solenoid contacts is by comparing the voltage on either Pin-4 or Pin-5 (I'm not sure which) to the voltage on the controller's B+ terminal. The controller activates the solenoid, so it knows when the contacts should be open and closed and when they are open, the voltage on Pin 4 or 5 will be higher than what is on the B+ terminal. With the resistor installed, the voltage on the B+ terminal drops to 3-5 volts less than the pack voltage when the solenoid contacts open, without the resistor, the voltage on B+ terminal drops to zero. That is why you only get the error when the resistor is installed. Let us know what the voltages are. I suspect one of those Pins will have 33V or less if the pack voltage is 38.2V. |
04-22-2014, 10:22 AM | #4 |
Not Yet Wild
Join Date: Apr 2014
Posts: 6
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Re: Possible bad resistor
17.1 before the pedal is pushed and 0 when it is pushed.
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04-22-2014, 10:47 AM | #5 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: Possible bad resistor
What pin is that voltage on?
BTW, unless otherwise stipulated , all voltage measurements are made with the DVM's negative test lead attached to the battery pack's main negative terminal. |
04-22-2014, 03:38 PM | #6 |
Gone Wild
Join Date: Jan 2014
Location: South Georgia
Posts: 1,120
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Re: Possible bad resistor
One of the things that has confused me trying to sort through all this is BATTERY + is not exactly the same as B+.
B+ is the voltage at the controller B+ terminal through the resistor across the solenoid or when the solenoid is energized. When the solenoid is energized and the wiring from the battery and solenoid is good and the contacts make, B+ will be the same as Battery + through the contacts. When the solenoid is not energized B+ will be slightly lower or if the resistor is open B+ would be zero or if the contacts in the solenoid are bad the voltage will be lower or near zero. Battery - is directly connected to B- on the controller so either point can be used as a reference to make most voltage measurements. Like Johnnie pointed out best to use the battery pack - as a reference point. Anyway that's the way I see it. Last edited by radioman; 04-22-2014 at 03:59 PM.. Reason: confused myself |
04-22-2014, 05:09 PM | #7 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: Possible bad resistor
I typically use Battery Pack voltage, B+ and Pack voltage interchangeably, but B+ means Battery Positive as measured at the main positive terminal of the battery pack.
The B+ terminal on the controller is labeled "B+" because it is electrically connected to B+ (Main positive terminal of battery pack) when the solenoid contacts are closed. If not for the Pre-Charge resistor in parallel with the solenoid contacts, the B+ terminal on the controller would have Zero volts on it when the contacts were open. It is the Pre-Charge resistor that causes confusion and make troubleshooting more difficult. The purpose of that resistor is to reduce the arcing on the solenoid contracts when they close. There are several filter capacitors in the controller and if they are allowed to discharge, the inrush of current while the solenoid contacts are closing is enormous and pits the contacts. Basically, the $2 resistor prolongs the life of the contacts in the $100 solenoid, it serves no other purpose. (Other than confusing people ) |
04-22-2014, 07:06 PM | #8 |
Gone Wild
Join Date: Jan 2014
Location: South Georgia
Posts: 1,120
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Re: Possible bad resistor
Well the battery positive should be called B ++ and the solenoid output should be BS+. As long as we understand it we can deal with it. It is too late to change it. It is hard to explain this sometimes to someone who has had a golf cart for several years and suddenly it stops running. I know the feeling. You flip the seat up and look at all those wires and wonder how to find out what is wrong. That's how I wound up here looking for help with confusion over the Inductive Throttle Sensor and how to check it.
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04-22-2014, 08:23 PM | #9 |
Not Yet Wild
Join Date: Apr 2014
Posts: 6
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Re: Possible bad resistor
When we check B+ it measures 19.8 before the pedal is pushed. After the pedal is pushed it reads 36.6. The batteries are at 37 not fully charged but close. Reading at J1 pin 4 is 36.9 before, 36.3 after. Reading at J1 pin 5 is 36.7, 0 after.
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04-22-2014, 10:04 PM | #10 |
Gone Wild
Join Date: Jan 2014
Location: South Georgia
Posts: 1,120
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Re: Possible bad resistor
Look at the diagram JohnnieB sent. J1 pin 5 should be at battery +. It seems to me the wire on J1 pin 5 should be connected to the battery + side of the solenoid contacts. Looks to me like a resistive open wire somewhere between J1 pin 5. and battery +. The red wire on the Reverse Beeper should be at battery + also. Curios what the red wire on the backup alarm would read when the pedal is pressed.
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