Need help with component diagnostics!

Are you running car on stands or are you actually rolling 2 feet before cutoff?

And when it is cutting off at 2 feet, is the contactor kicking out? Or is the controller pulling off power?

actually rolling. 2 feet, about 2 seconds of accelerator activation, then acts like I turned the key off. contactor disengages, odometer reading displays for a bit, 0000 on the BDI, then all off. turn the key off then on & it resets to acting normal.

Think the controller is calling the shots here.

Getting a little confused on the threads here, so jumped back to this one.
Controller is a T2. no capitals in my email address. Pretty sure I can pull the PC boards out of the sealing goo on each end so I can get a better look at both sides of both boards.
The motor is a 7hp from Ride4fun. This cart has some wickedly tall gearing, and I sent this controller to Ride4fun to re-calibrate the speed. The speedo reading was further off when I got it back, but didnt want to pull it out and ship it again.

What other threads are you reading?
Yes- It can get very busy when multiple suggestions and directions are offered up as solutions.

Don’t go pulling at the PC board just yet. I want to go in another direction first.

As I had the T2 controller out, open and on my bench I did some close visual inspecting and probing of the mosfets. Everything looks good visually. no blown caps, to burns. one mosfet tested bad, so I have one coming. May or may not be the cause of my woes, but it’s something. Pretty sure I can replace that component without tearing up the T2.
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Its the mosfet on the far left.

What other direction do you think we can explore?

Here is a thread from some of our legacy members that more/less goes down your path- Some of this is on later controllers, but I think it all applies.



Where I was going next was to have a quick look at your motor. Depending on the last time it was done, It may be in the need of a service. Sometimes a bad contact on the brushes can cause some pretty big spikes on the feeds. These can take out a controller.

Depending on your motor, at least take off the inspection cover and blow out the black carbon dust. Give each brush spring a flip and see if a brush is stuck. See if you can get a good look at the comms as you slowly roll the car a bit forward/backward.

An audible clue would be some low level grumbling and maybe even some sizzle-popping when under accel. It’s easier to hear when dash is off for a test drive.

As this cart has been sitting unused in the weather for a year or so, I’m planning on going through everything. I’ll put the motor on the list. It’s a 5 year old 7h with probably less than 300 miles on it. Brakes, bearings replaced 5 years ago also, but sitting is a slow death. Repairs and painting the abs pcs too, but none of the above until I have a runner.
Have a rewarding year’s end holiday season. I’ll be getting back on this after the 1st.

This is EXACTLY why I ask so many questions. What first looks like a simple problem sometimes has deep roots in other parts of the car.

For sure- pull that motor and get it out on top of the bench before trying out your repaired controller. It comes out easy and far easier to get to all the way around with the motor on the bench.

  • You may not need a full rebuild, just start with pulling the band cover off the end and inspect each brush to make sure it is not stuck in it’s holder.

  • Blow out all of the dust(do it outside).

  • Meter all the connections.

  • put a finger of spline grease on the coupler


→ As per those other threads, You might want to replace all of the FETs in the group while you are in there.

There are 2 Fets of this type in the T2. Replacing both.

If it’s been sitting in the grass for all that time, and stuff is rusty and crusty, check the wires attached to the brushes and make sure they aren’t corroding. The last thing you want is for one of them to break and arc onto the brush holder.

Where’s your sense of adventure?

No adventure needed. Luckily I caught it before it fried the controller.

Bloody spectacular mate! I bet that smelled wonderful.

Thanks for the tip. I’ll pull the motor and check it out. The original motor died like that.

Ok, I have replaced the 2 fet’s in the grouping and they tested OK. reinstalled the controller and same symptoms. no contactor engagement, 57 & 66 error codes.
I manipulated connector MH20 at the controller and BDI blinks to 04, making me question all the contacts there. I am now chasing all the wires and connections for any faults. If everything checks out, I think its new controller time.

I assume you checked out all the FETs before putting it all back together.

Are you getting the 04 consistently?
Have you tried lowering the parking brake to clear it?

Did you go through and/or check out your motor?

I did check all FET’s. The only area of the controller that I couldn’t visually inspect was the bottom of the lower board, as it was locked in by the end cap sealant globs.
I took apart the MH20 socket and carefully cleaned and tightened each female terminal (using 10x glasses, feeling like a micro-surgeon) 04 issue fixed, and now the contactor activates correctly. Sort of…
Today I pulled the motor. It was a mess, with 3 of the brushes seized in their housings. Did a complete disassembly & cleaning including polishing the commutator on a lathe. Reassembled and reinstalled.
So I think I have fixed at least 4 issues.
Remaining problem is the the cart shutting down after going a short distance. Symptom is like the ig. switch is turned off. -contactor disengages, -BDI goes blank, -no codes. Turn ig. sw. off then on resets to normal, until cart goes a short distance. Problem consistant in both modes and directions.
I am now going to verify the accelerator micro switch is functioning normally.
Think I’m getting closer to cornering all these gremlins.

Momentary Throttle switch issues would not shut off the PID.

Monitor the V from the converter. If it takes a dive then look at the key switch or the DC-DC converter is shutting down due to a short.

Just to recap cart 's current issue, after MH20, controller and motor work:

key on, brake on=04 @BDI; brake off charge level then speed @BDI (normal); accelerate and within 2-8 seconds the cart acts as if the switch was turned off, contactor disengages, BDI displays milage, then 0000, then off. So a random ‘key off’. I call this “dropping out”.

Following your advice, adjacent the converter I hooked V-meter from red to chassis, then orange/green to chassis. Interesting things (clues?) observed.

No change in voltage when cart drops out.
BUT, observed that voltage DID drop when the brakes were applied. Red dropped 13.3 to 1.1; O/G dropped 13.3 to 8.1. Disconnect either upper lead on top brake switch and voltage does not drop. Normal?

Could this key switch drop out emulation be a controller issue? or is it a wire/switch issue?

I noticed a 2 wire harness coming from the steering column that had been cut. Assuming this happened during the PWB conversion/upgrade.

This is ruining my dry January!