Hey community. While doing some testing, I found 72v (actually packV) on the chassis. Meter (black) was on B- on controller lug and (Red) was on chassis. Here’s my specs:
All pre-2004 harnesses, components, etc
Has the recall DC-DC upgrade
T2 controller
72v Lithium
New rebuild and still in the testing phase. No prior working knowledge of all the components"
I needed to clean up all connections more thoroughly so, I started at the B+ stand off lug with the white wire:
Disconnected DC - 72v still on chassis
Disconnected Relay - 72v still on chassis
Disconnected Buzzer - 72v still on chassis
Disconnected 20pin IP - 72v still on chassis When I disconnected the 23pin at controller, it went away.
So I’m assuming the short is downstream of the B+ at Pin 1 on the controller.
Any components known to cause this issue? Any guidance or wisdom is appreciated!
Thanks in advance!
Connect a 10k resistor from B- to chassis. Effectively across meter leads. Chassis is isolated, floating from traction battery.
If 10k brings it down it’s fine. A high impedance meter will measure static, phantom, voltage.
If you still have battery voltage with meter shunted by 10k, then continue your search.
Yup. Klein model MM720. Its pricey but worth not having those headaches. Has 6k resistor built in and design for those “phantom” readings. Thanks again!
Try dismounting the motor controller from the chassis firewall and do your meter test again.
Slide a piece of cardboard in between so it is not touching chassis.
If still present, disconnect the cables going down to the motor. Field wires first, then the Armature wires. (It might be easier to disconnect off the motor, rather than approaching the connections on the bottom of the controller).
@Inwo no luck. I tested from B- lug to chassis. Got packV. Used a 10k resistor got around 60v. Used my new meter with built in LoZ which is 6k and got 20v.
@AssyRequired ill try the controller and motor wires next.
@inwo yep. Unfortunately its not just phantom voltage. Ugh. Charger is new lithium. Old zivan removed and charger curoff is bypassed. Ill keep moving down the line past the pin1 on controller
The test using the 10k tells me this might indeed be phantom/leaking voltage. It dropped quite a bit Down 15V? What watt resistor did you get? Was it getting hot?
Also double checked with your new meter? (Phantom V dropped to 20v)
Ill keep moving down the line past the pin1 on controller
Unplugging the 23p - the voltage goes away? ← This means the issue is in the controller or something related. NOT in the harness/related to Pin1 wiring.
@Inwo@AssyRequired I definitely don’t have a strong understanding of the resistor test, it’s new to me.
First test was my old MM. black probe to B- then clipped a 10k resistor to the red probe and touched it to the chassis. Went from 72 to 60v ish. I didn’t notice it getting hot but didn’t check either.
Second test was my new Klein MM720. “Low Impedence (Low Z): Input impedence >3kΩ. Max input 600V RMS”. But I read this elsewhere “3 kΩ to 12 kΩ depending on the voltage level”. Results were down to 20v ish when testing Black to B- and Red to Chassis in the LoZ setting.
So with my limited understanding, I thought the resistor would completely “filter” the voltage.
But you think the drop down to 60v or 20v using in between 3k to 12k resistor would considered phanton/leaking voltage? minor enough to ignore for the time being?
Tough to say without knowing what is leaking.
It is fairly common to see maybe 1/2 (half) PackV leaking to chassis, Possibly due to leaky rectifier somewhere)
But I have not seen Full PackV before. It might be worth tracking down.
I suggest isolating controller and/or motor (as suggested above).
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Speaking of missing something…
What was the result of the Pin9 - (pedal ground) pin repair? (from your other thread) Did it work? Did I miss the update?
@AssyRequired I did update the prior thread about Pin9. Was resolved by running a “homerun” ground from red wire at POT to the B- lug as you suggested. In the process of adjusting all the fins in the 23pin connector currently.
Will try to isolate and test as you suggested.
Actually found something else odd and could be the cause.. Found a Gry/Wht wire to Pin21 going to controller. It has continuity to the Gry/Wht going to Pin2. It is not in the wiring diagram but it is in the T2 controller schematics and labeled as “MOTOR THERMAL SWITCH”. I’m assuming it should not be getting a steady 72v and that this may have been some “fix” from the PO?
I saw your post about running the jumper wire, but that was meant only as a test.
It sounds like you stopped at your jumper wire?
Did you try and inspect the pin spring/wipers as I suggested?
(public readers will not realize I sent OtisMoon detailed instructions on how to check/adjust the tension on the pin wiper springs several days ago.
In the process of adjusting all the fins in the 23pin connector currently.
This sounds like a “no”
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Found a Gry/Wht wire to Pin21 going to controller. It has continuity to the Gry/Wht going to Pin2.
Yes, I am aware of that wire. That wire was added later and is normal.
P2 and your P21 should not have B+ on it until KeyON.
@AssyRequired Sorry, I’m always working on a main task and then side quests when the arise. It’s how my ADHD brain works. Once I finish adjusting all the fins, I’ll hook it back up and see if I’m getting correct voltage for pins7-9 from the POT. Hopefully that will be the end of that story. Fingers crossed!
The other “side quest” is that my main contactor clicks off after ~25 seconds from KeyOn. I followed your and others suggestions from a prior thread. I jumped the relay, WHT to GryWht, turned off after 25sec. I ran 72v+ from B+ lug to the main contractor, turned off after 25sec. Key switch had constant continuity. So figured I’d have a deep look at the 23 pin connector and adjust all the fins. This is when I found the Pin2 and Pin21 continuity. The problem is that neither Pin 2 or 21 have very good continuity to the start of the Gry/Wht wire at pin12 on the 16pin (former PWB) connector and maybe the reason the MC dies… and also, it could be leaking 72v from there.
Once the 23pin is adjusted, I’ll retest the POT voltage, test the MC and then get back on track with the 72v leak and isolating the controller.
I know, it’s a lot of different directions and probably deserves several different posts!
Thanks for everything!
What other thread was that? I think you misunderstood what might have been going on it there.
Ironically, this is perfectly normal behavior and not a problem. The controller will kick it out if there is no pedal activity and back in as soon as you press the pedal to go.
You seem to like finding problems where there are none.
Ok. That’s helpful, I didn’t realize it would automatically disconnect. I was reading the thread about sporadic MC and a poor connection at Pin11 causing it. Since I’m new to the gem world and reconnecting everything from scratch, I don’t mind disconnecting, cleaning, testing and putting it back together. Just gives me a better understanding of how everything works. Glad to confirm that my relay and MC are working proper. There’s definitely a poor connection in that Wht/Gry wire between PWB and 23pin. I’ll have everything back together later today and will report back on the POT and such.