Gem 48 Volt Wiring Diagram or Manual

Hello everyone, I am looking for a manual or wiring diagram for a 1999 Gem 48 volt car, The manual I have that goes from 1999 thru 2004 has no info on the 48 volt cars, Anyone have anything to help? Thanks.


Yes! Thank You! I got this car with no batteries so I put in new batteries, my 12v stuff does work but car won’t move or try to, when the key is put in reverse the beeper goes off, the charger is removed and the connector has been jumped, need to check that closer, My park brake switch has 3 wires to it, not sure why, diagram shows only 2 wires, they were disconnected when I got it, hooked them up as they appeared to have been originally, they are all separate wires, more testing to do.

It’s a shame there are no wire color notes on that diagram.
I guess to check if you have the right colors on the switch you could trace them back to the PWB as they attach to pins 3 and 4. Check with your ohm meter to see the switch close on brake drop - Or you could jump the wires there to see if your car will click and go.

Back again, I have 48 volts at the controller output terminals M- and A2 as soon as I turn on key and the contactor relay closes, nothing changes when I push on the accel pedal, should it be 48 volts all the time?

You should see voltages going up and down when measuring A1 and A2, but also on S1 and S2. If you just see volts going up you are probably just seeing saturated caps.

Chances are that your brushes are stuck in the motor.

With power off, Switch your meter to Ohms and measure between the connections on the motor. Remove one wire each off the A and S terminals. You will be looking for ~1 ohm on the A connections and 4~5 on the S connections.
If you see OL on your meter then the motor needs service.

I took the motor off and inspected it and ohm tested it and it was good, I put it back on and wired it directly to battery’s and it ran smoothly so not the motor, The wiring diagram does not show how the fwd.-rev solenoid is supposed to be wired, It doesn’t seem to be working at all or at least it makes no noise when I turn the key from forward to reverse, does it go through the control board or is it just powered by the key switch directly?

Did you test for power at the motor when trying to run the car?
You should see varying power on A1 and A2.
Also on F1 and F2. The F connects switch polarity when in Rev.

If you find power on the A lugs, and not on the F lugs then look for it on the direction Solenoid. If it doesn’t click then I’d look for a control Voltage.

You are right, The diagram does not show how the direction solenoid is wired up. I would look at a golf cart diagram for clues.

A-1, A-2, F-1, F-2 All have 46.5 volts at the same time no matter what I do to the accelerator peddle
It is the same voltage that I have on the output lug on the main contactor, I lose a couple volts through the contactor but have jumped around it to make sure it wasn’t causing the problem.

Odd Q: When checking these posts for power- Where EXACTLY are you placing your probes?
Example → When testing A1- red probe touching the bolt, Black one touching (?)

Ground probe on the controller battery negative post, (B- on diagram) Positive probe on each of the 4 motor terminals for each check.

I just did a voltage drop from the controller negative cable to the battery post to make sure I don’t have a bad cable but it’s good 0 volts.

Ah- that’s what I thought. You misunderstood what I was asking you to do.

Measure directly A1 and A2. One lead on A1, the other on A2. This will show you exactly what the motor is seeing.

Same goes for F1 and F2. Across those two points.

Then post a pic of your Direction Relay.

0 Volts measured across motor terminals as specified

Going back up to your E-brake switch. Did you ever get that sorted out?

You said the charger was disconnected and the interlock Bypassed. Did you confirm this?

When you switch from Fwd to Off then to Rev, does the direction relay click?
Previously you said a main relay was clicking as soon as you switched the key On. Is this what you meant?

I have not done anymore with E-brake other then try unhooking wires to see if there was any change, I did install the charger and reconnect the molex connector harness that contained the jumpered wire, I have not connected the 48 volt charger output wires yet as I am waiting for a connector to mate gem car charger harness to charger, Not sure if charger needs to have the 48 volts hooked up to control the interlock?

The main relay clicks in both fed and rev as soon as key is moved to that position, beeper comes on in reverse, the directional relay does not click or appear to operate at all.

I did try apply 48 volts to the terminal on the controller that “wakes” it up but that did not change anything either, I will trace down the park brake wiring and see where it goes to and voltages on those wires.

Be VERY careful about applying power to check things out. That is a good way to blow things up. Some things may take 48v, some take 12v)

Instead- Check for expected power at locations.

I did go to the Curtis web page and found the data sheet for the controller, it says that 24-48 volts applied to that terminal will turn on its function, it has 24 volts going to it on the factory harness,

parking brake switch is as follows, Blk wire= 24 volts and goes to module top 2 pins are empty this one goes to 3rd pin from top, Green wire has 50 volts and goes to next pin down on module or 4th from top.
White wire runs to steering wheel connector and there is no wire on the other side of the connector so it ends there.
Here is switch and wiring pictures, The white wire is dead and is on the common terminal,