2005 Gem E4 error code 21

yes error 21 still shows up on the display, no movement in forward or reverse

Is contactor pulling in ? The big clunk.
Are you sure the battery is connected to B- on controller.
If you have 72v at P1 and P2, then p9 will be +5 to +12 v, and P8 0v.

P7 causes the error when over 4.5 volts. You will need to pin those to test. Unless you don’t mind cutting the insulation a bit.

When I get back I’ll check to see if the contractor moves when I release the brake, but I haven’t heard the clunk noise since this error 21 showed up on my display.
I’ll send you a picture of the controller hooked up with the cables in a little bit. I’ll try to get all the cables in the pic so you can see if I re installed the new controller right. It might be user error causing all my issues hahaha

Or my error. Communication can be a ■■■■■.
The error probably prevents contactor.
If you connect P7/white circle to B- the error will go away or change.

I connected a T4 here and got proper volts from 7, 8, 9.
If you don’t with P1-2 powered, controller is bad. Did they send the same one back? A different one would not have the same error.

Can I buy your old throttle when we are done? Need for trouble shooting.

just so I am clear on P7 are you saying connect a wire from P7 (white circle in your pic) directly to negative battery post or do a voltage test from P7 to B- ?
I will also strip back some insulation from P1,P2 and P9 so I can get voltage readings.
If you end up helping me get my GEM running I will give you my old accelerator pedal as a thank you.
Yes they sent me a rebuilt one so a different one than my old T4, they kept my old T4 as a core swap

Chances are slim you got a rebuild with the same issue. I don’t trust fspi. They may have put yours in a new case.
Both, measure volts on p7 with and without throttle connected.
If it is ever over 4.5v connect it to B-.
Also p8 and p9.

Even if p9 is dead, p8 should hold p7 low when throttle is connected.
You may need to cut p9 wire. If it was shorted it would not show volts.

ok, so I double checked the connections to the controller and the positive and negative are connected to the right areas on the controller.
with the throttle disconnected p1 and p2 both show 76 volts / p7 , p8 and p9 all show zero volts.
with the throttle connected p1 and p2 both show 76 volts / p7 and p8 show zero and p9 shows 4.7 volts finally p9 shows voltage but only with the throttle connected.
what’s the next step

Great information. I will need to study the gem wiring to see where the 4.5v is coming from.
Are you reading correct pins? 8 is the last pin in the first row. 9 is the middle row next to p1.
Sorry, I have to ask when things don’t seem right.
The only place the 4.5v can come from is p9. Without throttle it rises to 12v.

ya no worries, I double checked the pin locations and yes p8 (white with purple stripe) is last pin on the first row and p9 (green with purple stripe wire) is first pin in the second row closest to p1 and p2 (white wires) I also noticed on the connector the beginning and ending numbers for each row are printed on the plug. I only get a voltage reading off of p9 when the accelerator pedal is connected to the harness, once I disconnect the pedal the voltage goes back to zero. I stripped back some of the shielding on all the tested wires to make sure I get a good connection with my meter.

The plot thickens.
I’m stumped but hang in there.
This car ran before this issue?
No wires have been swapped or repaired during the ordeal?

We need to find the source of p9 's voltage. No problem if it was here. As much as I hate to see this happen, I’m afraid you will need to cut wires.
As pin 9 is the only one live. It will need to be cut to see which end has voltage.

One other possibility. P3 has a pull up resistor that holds it high until throttle press.
This wire is routed in the same harness. There should be no connection to other throttle wires. 5 total.
See if by some freak chance p9 drops to zero when applying throttle.

Also get a reading from p3.

Ok. I have no clue what is going on!!! Now I have zero voltage at P9 with and without the throttle hooked up to the harness, I’m back to where I was before rrrrrrrrrr. P3 has no voltage reading both with and without the throttle plugged into the harness. You think maybe there’s an issue with the new controller. I can always call FSIP tomorrow to see how I can get them to switch this one out. I’ve only had it for about a week so I’m sure it’s under warranty

It appears that way. All your wiring checks out.
Two issues from what you have told me.
No voltage on p9.
Code 21 even though p7 is zero volts.

It is possible that low voltage also triggers the same code. If that’s true there is a work around. Supplying the p9 throttle voltage from another source.

Your whole 12v buses may be dead or shorted. Look for 12v red to blk on motor sensor. That’s an easy one. Unplug it at the motor.

Ok my stupidity is going to come out lol. What power supply should I use to connect voltage to p9 for the work around. And the mention of 12v buses and disconnecting the motor sensor I will need help with . Sorry

Not important. Just unplug the motor sensor and check voltage.
If it comes to needing a work around, I’ll help.

Internal to the controller is a 12v regulator that powers inputs and outputs. It is one of the functions that can be tested with sentry sw.
Measuring the open circuit voltage at the motor hall affect sensor will tell us something.
I’ve never seen on shorted, but in theory it could shut down the 12v circuit. Which would lose power to the 5v throttle supply. P9.

If we suspect the controller is ok, I can build you a test plug for the controller to measure pin volts with only 1 & 2 connected.

checked the motor sensor and it’s getting 12 volts. I’m going to call FSIP to see about switching out this controller, any ideas of what I should say to them so that they don’t try to tell me the controller they sent me is good.

Only that p9 has no voltage to throttle.
Check it again with 12v motor sensor unplugged.
If we need to go further, I will send you a test plug for controller. Wires for P1 & 2.
Wires for 7, 8, & 9.
You can do the same if you find a way to power pins 1 & 2 only. Then probe p9 with meter.
I have the tools, but you would need to be creative.

unplugged the motor sensor and still no voltage readings off p9.

Let me know what FSIP has to say. I don’t think further testing will be productive.
All my advice was assuming controller was ok.

so FSIP, told me this time that they did rebuild my controller I sent them, so they did not send me a new re manufactured unit like they told me originally. Now I have to pay for shipping again to them but they said they will take care of the shipping back to me. Hopefully they fix it right this time. SOOOO most likely they didn’t fix it right the first time and just slapped a new outer shell on my old controller to make it look good.