2002 GEM E825 2 Seater NOT WORKING (Kinda)

GEM Forum
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1

Hello,

We will start this story off a long time ago (no not in a galaxy far far away). But when i purchased an 2002 GEM last year, I didn’t get to drive it much, but when I did i didn’t use the radio until one day, and lets just say who ever installed was not the brightest bulb, and on that day the radio burns up and so does the radio wires and it starts to smoke, and one of my 12v batteries decided to get nice and hot and melt, so i decided to put lithium in it, well now the fun part. I have read just about every post on here about 02 Gems and it seems we all have close to the same problem but the fixes are almost always different. So here is what I have done besides cuss like a sailor on shore leave!!

  • No lights on instrument panel (unless I jump the relay) and then everything works (meaning I can drive)
  • Bought a new relay and installed, Nothing still.
  • Testing the DC Convertor and here is where it gets tricky for me, I’m getting 28V out of the wire going to the fuse box, Now I’m testing it from the red wire to the -B on the Controller, I cant seem to get a reading if I do it to the frame (which baffles me) I did clean all the ground wires and make sure no corrosion
  • I tested all the wires from the controller that i can and i get 78Volts from the white wires to the convertor.
  • I don’t know how to test the light timer
  • Tested the key switch and I get 28v to that and think that is supposed to be 12v??
  • I have pushed, pulled and moved around every wire not once, twice or three times a lady!! I mean 4 times at least@!!

So I feel my DC convertor is fried or something is not going on there like it should, Im also concerned about the light timer and relay, I do have a new relay coming in tomorrow and I want to buy a cheap light timer off of ebay to check, those puppies are 100.00 bucks!! Any suggestions? Thoughts? Ideas besides me burning this thing to the ground!! My brain hurts!! HELP!

Thank you,

Brian

2

This means your car was late enough in the run and did not come with factory pulse cannon option? Dang…

You might still have residual PC wiring still in the car tho. You really need to pay attention to what accessories you are hooking up and to where. It might be the cause of your old stereo release of the smoke. Whatever it was, study what was done and DON’T do the next one that way.

It sounds like you have been exploring the archives a bit. This is good! You may have run into the electrical description these cars are running.
If not. consider this a refresher.

You will find two independend/isolated DC power systems.

  1. Drive/Traction system. aka → PackVolts or 72v.
  2. Acc system - 12vdc used for low voltage switching and powering convenient automotove accessories. (lights, wiper, horn, mirror ball, etc.)

When testing/diagnosing one of these systems, it is important to use the correct reference(where your black probe is touching), otherwise you will get a strange result and not worth any real result.

For drive system (72v) - use the closest source for B-.
For Acc (12v) use ChassGnd.

Follow?

===

Moving on…

No lights on instrument panel (unless I jump the relay) and then everything works (meaning I can drive)

This is good. It means your drive system is ok.
You are correct in the need to look at the DC Converter.

testing the DC Convertor and here is where it gets tricky for me,

Assuming you have the Surepower DC Converter upgrade? (black box with fins)

If yes. Verify that Pins 1 and 12 have Pack V(72v). (This is the input)

surepower pinouts
surepower pinouts1868×1184 183 KB

White is usually B+, Green is usually B-.

When testing these two wires, Use the proper reference. (Not frame/chassGnd)
B+ can be found over on the right side of the dash on the bug fuse.
B- can be found over on the motor controller (right side big cable on top).

===

If you have PackV going into the converter, check it’s fuse. Some early surepower units have a tube fuse accessed in the end where the harness connects to the converter. (yours may not have a fuse).

IF you have B+/PackV going in, look for 12v coming out on Pin/wire 9&10. Ref Frame Chass.
I believe those wires are Blue. You will find one (unswitched 12v) over on the timer.

Follow so far?

3

Thank you for the reply,

  • So I have 78V from the Green wire and White wire, so that is good.
  • Next I tested pin 8 and 9 (mine are orange and green) grounding to the frame, NOTHING, NADA, ZILCH! I tried several places on the frame, Now one goes to the ignition and the other goes to the light timer, where those the ones you wanted me to test??
  • I then tested the red wire going to the fuse box and NADA also, unless you touch the B- on the controller and then it reads 28V like it does with every wire I test, So either my ground on my frame is freaking out or my convertor is FRIED,
  • Also tried the blue wire (Pin 3) and nothing there, NADA also.
  • Next in line are the 3 black (ground wires)

So really i have to believe its the convertor, maybe when the one battery melted and put a surge in the system that fried it?? Thoughts?

4

In the future -
Be careful of wandering off script and/or jumping ahead.
When I offer suggestions you need to be accurate and follow those instructions.

I did not suggest doing anything other than testing 1 and 12 (white and green wires), and 9 & 10 to ChassGnd. Depending on those results, I would suggest the next step.

Pin 8 (orange) is switched output and would not have anything on it at this point.

I then tested the red wire going to the fuse box and NADA also, unless you touch the B- on the controller and then it reads 28V like it does with every wire I test,

Red wire would not have anything on it either. Test tells me nothing.
Measuring Red wire to B- is mixing your references and always gives an invalid/bad reading that means nothing to our goal here.

Pin3 (Blue wire) would not have any V on it at this point either.

Understand?

Did you check your Converter to see if it had a fuse? Some early surepower units had a round knob off to one side with a screwdriver slot in the center. This was a replaceable fuse.

5

I do not have a fuse on my converter, that would be to easy with my luck.

Thought?

6

Hey Brian, sounds like you’ve really been through it with that GEM. From what you’re describing, it does sound like the DC converter could be the main issue, especially since you’re getting 28V instead of 12V where it should be. That might explain why your lights only work when you jump the relay. I’d double-check all your grounds again, just to be sure none are loose or corroded under the insulation. Also, since you’ve had a melted battery and burnt wires before, there’s a good chance something in the wiring harness got damaged and is causing a bad connection or voltage drop. Replacing the relay is a good next step, and testing with a cheaper light timer makes sense before spending more money. Take it one part at a time — don’t lose patience, you’ll get it sorted out.

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@tonni6030 - Not to discourage your input and your attempt to try and help out, But it sounds like you need to be made aware of the same mistake Vibe is making here.

Scroll back up to my Post2 (above) and understand that mixing reference points (grounds) is not a good idea. These cars have 2 voltages that need to remain isolated.

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Yes I appreciate your input, I wish I would have known about the two different grounds before, would have made me my life a lot easier. :joy: I have been chasing ghosts it seems.

Any thoughts :thought_balloon: on what I can do next?

9

As you found out by jumping KeyRelay, Your car does not need 12 to run/drive.

But it DOES need 12v to activate that KeyRelay and power the 12v subsystems (lights, wiper, horn, etc).

The simple solution is to seek out another Surepower DC Converter. This would be a plug/play solution.
Sometimes you can find one from a seller that is parting out cars.
They all seem to be a bit proud of what they are selling.

I have been looking at some of the cheaper DC Conveters out there. It would no longer be a plug/play option and take some wiring skills. Not all will work. They need to have their input V isolated from the output (grounds). I have not had a chance to order and pick an ideal unit yet.