A teacher at one of the schools I’m working at was having problems and asked me if I could help and I think I have it debugged down to the Contactor being bad.
There is a large wattage resistor across the power connections of the contactor and I get the following symptoms:
With the key ON for a minute or so and selector in Forward, when I depress the throttle pedal I hear the switch click and then feel the smallest of oomp of foward motion and that’s it.
The batteries are all over 8.5xV and hardly dip when the headlights are turned on so batteries are good.
The controller capacitors trickle charge resistor(across the heavy connectors of the contactor) gets slightly warm when trying to make the car move.
With the key ON, pedal OFF there is 0V across the low power contactor connections but when I press the throttle pedal there’s 49V across the low power side of the contactor. There is also 51V across the heavy connectors of the contactor.
My diagnosis is that the contactor is not closing and has failed. Someone else troubleshot the golfcart a year ago and replaced the key switch, Contactor and Forward/Reverse switch because that’s how they troubleshoot things, ie replace until something works. I didn’t want to manually short out the main/heavy connections on the contactor without a schematic or knowing what the normal operation is.
Thoughts and I’m fine with “it’s not a GEM, go away”.
I had not wanted to do that unless I was sure about it not blowing up the controller by powering it up when it wasn’t expecting to be fully powered. Having experienced some odd controller smells when the T1 went AWOL after going over a hard bump and I manually threw the contacter only to have the GEM jump forward then die.
If the guy who swapped all the parts doesn’t replace the contactor for cost or less, I’ll give it a shot.
Thanks guys.
This explains a lot.
I think this cam caught one of your launches.
There goes another Gen1…
Dot starts off on left under the title bar. If you go full screen you can see the awesome front suspension detach off the front of the car.
I’m having a similar problem. I have a '94 CC 48v. Solenoid clicks, but no other movement or anything. I have been looking for a troubleshooting guide to trace the problem. I’m handy and use a multimeter well, but don’t really know what to test. One day it worked and the next it did this. I didn’t change anything it just quit. I’d be eternally grateful if someone has such a guide.
Pictures attached
All I did was:
1)measure the voltage on each battery and make sure it was FULLY charged.
2)turned the headlights on and made sure they were fully on and measured the voltage of the batteries and made sure they were still at the FULLY CHARGED level. dropping .0x volts was acceptable but not dropping a tenth of a volt or more.
3) look at EVERY high power cable connection and if there is rust or discoloring, remove, wire brush to clean metal(no oils or grease) and reassemble.
4) looked at the F/R switch to see it was in good working order and copper pads were not burned. You couldl even do voltage measurements at the output connections behind the switch.
5) listen for the switch clicking as the throttle pedal is moved off of 0 position
6) listen and look for any element of motion or motor movement as the pedal is moved towards 25% throttle.
7) measured the voltage across the contactor low voltage(small wires) terminals.
0V at 0 throttle
battery voltage as the throttle is moved off of 0
8) measure the voltage across the contactor power cables(big wires) terminals.
something at or less than battery voltage when the key is turned ON and Forward selector position
note: the resistor might get a little warm as there is small current pre-charging the controller capacitors and then there’ll be no more flow and the voltage will stabilize accross the connectors
9) measure the voltage across the contactor power cables(big wires) terminals
should read 0V when the throttle is moved off of 0 position and there could be a click as the contactor is thrown.
10) try turning the motor while all the above have been checked and throttle is moved towards 25% to see if there’s any motor brush issues causing intermittent operations. Try in both directions.
11) If there is not battery power on the low power wires test the throttle switch and POT and that the signal gets bck to the controler.
12) check that the key switch is working all the way back to the controller.
13) look for any disconnected, broken, damaged low power(small wires) wires or connectors.
14) Launch into a decaying orbit around the Sun…
Thank you for the quick response. Most of that makes sense. My biggest problem is which contacts you are testing with. The power wires are obvious. Testing across the two posts on the top of the solenoid is clear, but when you said the lower terminals, I’m not clear which ones. I have 4 terminals on the side of the solenoid, two have the Diode across them and the other two come from the Pot and the controller, I believe. Are those the two terminals where you test the Pot resistance? But, I seem to gather that if I get pack voltage on the solenoid without pushing on the pedal the solenoid is bad?
Again, Thanks
P.S. I just bought an old GEM. I may have a tandem launch into the Sun one day.
Aren’t those 4 terminals on the side of the solenoid electrically only 2 conductors?
The CC I just looked at had both terminals and spade lugs for the love power side but they were electrically the same. ie 6 terminals but they were connected as a pair of 3 terminals.
The four spade terminals on the side are two pair of Positive and Negative. One is used by the Diode. The other pair is for the Pot and the Controller. Obviously the two top lugs are the power
if there are effectively only 2 electrical connections there then it makes very little difference which terminals you measure across as long as they are not the same electrical connection.
