Gem won't start. Need help!

Hey all, I’ve searched all over the forum and read through others posts I can’t seem to locate my problem.

Bought a 2000 Gem about a month ago, batteries were new last May. Came with all receipts, Delta-Q Quiq charger is only 2 years old. I charged it up overnight and checked all my water levels this morning. I brought it around to the garage where I was going to work on getting the headlights and turn signals working.

There is a 4 wire harness that runs out to the hood for the lights and turn signals, the horn and wiper also branch out from this harness as well. I found a grn/ylw wire not connected and figured it was a ground, got the lights and turn signals working. All was well… until

I got in and turned the key, nothing happened… it still buzzes if the parking break is off in “road” mode. But I have no display, nothing happens. I checked all the under good fuses, all working. All my accessories and lights still work, so the DC-DC converter is OK. I’m at a loss. I did plug it back in and it charges, battery pack voltage is right about 76V.

For reference I don’t have the PCB style dc converter, mine is the aluminum finned style.

Thanks for any assistance, I am an electrician by trade and I’m pretty familiar with this system. But I’m really at a loss here. Just baffled at what could’ve caused this. Ran fine until today.



what does this mean? You figured they were ground so you grounded them to the frame? Did nothing with them?

Yes, it’s a green wire with a yellow stripe. This color combo is “typically” ground and it was cut off near the ground location for the headlight circuit. I did trace it back to the wiper motor before connecting it to ground. So, the wipers are working now.

I did find and download the service manual. Doing my due diligence working through the troubleshooting portion of the manual.

In the Drive and Power Troubleshooting Chart A;
I measured battery voltage on each side of the fuse 76V. That’s fine.

What gets me is step 6: “Measure voltage on the output side of the main connector. Is the voltage approximately 72VDC?”

If Yes. Check the voltage on the B+ Input of the Motor Controller. If the voltage is approximately 72VDC, replace the Controller…

They’re not exactly clear on which motor controller. The manual references both the Motor Controller (for supplying voltage to the drive motor) and the PWB Motor Controller (the Motor Controller Controller)

The PWB makes sense seeing as how it’s function is to tell the motor controller what to do. But it still makes no sense why it’d crap out. Bad timing?! I have some more digging to do tomorrow.

Since you verified there’s 72V(batt V) on the converter and get the expected ~13.5V, I would also look for the low current 72V to the controller. Most here will consider the T1 motor controller as “the controller”. ie the one with the large orange power and motor cables. And you should hear the contactor closing when you turn the key on with the e-brake released.

Green/yellow is supposed to be cut at 4 pin harness to hood. Iirc, its a positive ground for the wiper motor so that it will auto park.

Lights and horn are frame ground on my 02 cauck (CArt-trUCK). Screw located on framerail by horn on mine

The wiring print for 99-04 is not in the service manual. Its a separate scan. Post email and will send later.

The contactor doesn’t close when the key is turned. That’s what tipped me off to something being wrong.

I have to go out and verify that I was checking the B+ Input on the T1. I assume there’s 4 major connections;
B+ and B-
M+ and M-

I was checking the voltage on the top set of connections on the T1 Motor Controller.

On later cars the contactor doesn’t close until you press on the GO pedal a bit. Does it actuate differently on the early cars?

I find it odd that your dash pod display went out tho- Did you get that working again?

(rather than your present path of checking for power at controller)
Perhaps there is something related to rummaging around in the wires? These are 21 year old connections all over the place.

Been a while since I powered up the 02, but IIRC - key on, contactor engages, if you don’t drive immediately, it times out and opens. Other than that, it only engages when you stomp the loud pedal - then times out when you are off it.

My main contactor would close as soon as the key was turned with the parking brake off.

As far as rummaging… I’ve only started that after I noticed a problem. I couldn’t see how my meddling with the accessories would kaput the Motor Controller (T1).

I’d hate to shell out for a replacement controller. But that’s what it looks like right now. I’ll continue to update with my findings.

What I was getting at is why are you blaming your controller? (defined as the big grey box with the big orange wires going to it that the motor hooks directly to.)

You may be still confusing it with the PWB/car controller?

Did you get the wiring scan from JrJ?

I’m only pointing a finger at the Motor Controller because that’s where I left off with the troubleshooting in the service manual.

I checked the output of the main contactor with the contactor open. It measures 72+VDC, then measured the B+ Input on the Motor Controller. Also 72+VDC.

The manual says if you’ve got 72VDC at both points, replace the Controller. If no voltage is present at the output of the main connector you proceed to checking out the PWB connections, like the key to the main contactor coil, etc.

I haven’t gotten a wiring scan from JrJ, at least I don’t think so… and the BDI is still showing nothing.

This may sound silly, but go back to what you changed and review that first. Unground that grn/y wire and see if it acts different.

Reason being is that I don’t see that color wire in the wiring diagram associated with the headlight harness. Perhaps it was added by the PO?

Granted- you are also working with a sort of hybrid harness since you now have an updated dc-dc converter and a new DQ charger. Things will be different and who knows what other hacks have been done.

I did remove the grn/ylw in question yesterday when I realized it wouldn’t turn on. Also unplugged the headlight harness (which was also not connected when I bought it) had all the accessories working but then it wouldn’t start at all. So I put it all back to the way it was when I bought it. No effect on the situation.

It does have some aftermarket items like the charger. I believe that PWB is original, it’s just not the PCB style. The wiring isn’t perfect by any means. But since it was working just fine I haven’t messed with much under the dash. Just poking around with my meter mostly.

I do appreciate the help, thanks! I’d still prefer to troubleshoot rather than shell out for a replacement controller. On that subject, I see that Ride-4-Fun will rebuild our controllers for $499. Which isn’t terrible I suppose.

I can’t send you one until you send me your email address. We’re not allowed to post copyrighted material on this forum.

They just send them out to Flight Systems Industrial.

it’s on my 02’s chassis harness also, but only up to where the 4-pin connector that goes to the hood is located. it’s not one of the four wires though, it’s just cut and sticking out of the loom. No green/yellow wire on the hood part of the harness on my 02.

I haven’t had hands on an early car so I can only guess layout from pics.

You said you checked fuses and are all good. Maybe you missed one?

Start probing pins on your PWM. It looks like Pin 16 sends 72v to Pin1 on your MOTOR controller.
Pin 12 is keyed +72 that goes to Pin2 that wakes up your MOTOR controller and that feeds your PID.

If you lived closer I would let you borrow the 02 for a while to tinker with. Can’t really hurt it because it’s kind of already busted. :crazy_face: :crazy_face: :rofl:

You verified good battery power to the motor controller and told us the display on the steering column no longer shows anything and nothing but some weak buzzing when the key is on and you put it in forward witht he brake on. Correct?

I would look at why the controller is not powering up and where that buzzing is coming from. There is a 72V B+ to the motor controller, one which we often hack to fake a lower voltage for lithium upgrades, and I think there might be 12V line too. But what sticks in my head is the wire from the old Zivan charger which needs to be pulled low or else the controller will not turn on. It’s to prevent you from driving off with the charger plugged in so maybe that opened up while you were messing with the front end stuff. Something was done with it when they installed the Delta-Q so possibly the problem?

I think it might be Rd/Grn and is supposed to provide B- to the key switch which then lets the controller know the key has been turned. ie if the original Zivan was plugged in, it would throw a relay which opened/removed B- from the Rd/Grn wire to the key so turning the key did nothing because the relay had already removed B- from the key switch.

Did any of the trouble shooting ask you to verify B- to the key switch or Org/Grn pin 6 on the PWS?

@dougl - I also thought it sounded like charger interlock. Somewhere up there I thought he checked that. I must have read it elsewhere?

The early wiring diagram I have doesn’t even show it.

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