Brake the immediate throttle = nothing on MP4 (Problem Solved!)

[Ron]

This is a pet peeve of mine with the MP4.  When I release the brake and immediately turn on the throttle the bike doesn't do anything.  The e-brake cut off seems to prevent the bike from moving.  When this happens I turn off the throttle and it then works fine then.  The sequence seems to need the brake released and then a small delay before engaging the throttle.  Is there a work around for this?


<edit: changed title to add "problem solved!">

[RooGM]

How long is the delay?  I haven't noticed a delay on my MP4.  Are we talking a split second or something longer and more annoying?

[Supchrgamx]

crank your overvoltage protection up

[Ron]

How long is the delay?  I haven't noticed a delay on my MP4.  Are we talking a split second or something longer and more annoying?

Most likely just a bad habit of holding the brake while starting to apply throttle from the days of riding dirt bikes.  When it happens the throttle doesn't respond until I turn it fully off.  This off then on again doesn't take long once you realize what it happening.  Once I get the wheel back on my bike I can check but I think you can replicate it by holding the brake and starting to turn on the throttle. Then release the brake and continue turning the throttle.  I think the bike will not move now.

crank your overvoltage protection up

How would the overvoltage limit effect this?

[RooGM]

On mine if I'm holding the throttle in and I pull the brake, when I release the brake the throttle comes back on again.  I do not have to let off the throttle first.

[Ron]

On mine if I'm holding the throttle in and I pull the brake, when I release the brake the throttle comes back on again.  I do not have to let off the throttle first.

I'm not sure if mine exhibits this behavior every time or if it is only some of the time.  I'll check when I get the wheel back on the bike.

[Supchrgamx]

my delay got worse braking down hill
turned down regen and turned up my overvoltage and now works as expected

[Ron]

Crap!  I hooked the power up backwards when I installed the battery. Testing will have to wait until GM Canada can get me a new controller.  I'm mad at myself.

[Bikemad]

Have you tried reconnecting the battery the correct way around to see if the controller still works?

It might be worth trying it if you haven't already done so. 

Alan
 

[Ron]

After uttering some sounds that are not appropriate to type here correctly connecting the battery was the next thing I did.  Nothing happened when I turned the throttle.  At least I didn't take out my cycle analyst as well.

[Ron]

So I got the new controller installed and I'm up and running again.  With the new controller I still see the same behavior.  Here is a quick video showing how it works. https://youtu.be/I0PhmfKl27Y  Unfortunately brake then throttle behavior is consistent and I've never had it work any other way.  My setup seems to be cursed, between this and the lack of regen my MP4 seems to work differently from everyone else's.

[Bikemad]

Hi Ron,

After watching your video, it appears that the regen is now working, as the rear wheel stops spinning the moment the front brake is applied, however, the strange behaviour with the throttle and brakes certainly does not happen with my MP4 controller. If I hold it on full throttle and pull the brakes, it instantly stops like yours, but mine returns to full throttle the moment I release the brakes.

Your controller seems to be responding just as if the battery power had been disconnected and reconnected with full throttle applied. In this situation, a safety feature prevents the motor from operating until the throttle has been fully released.

If this safety feature is triggered by the turning on of the +5V supply, I'm wondering whether there could be a problem within the front harness which is causing the brake switch to temporarily short out the +5V supply either in addition to (or instead of) the brake signal wire, which would effectively be turning off and on the +5V supply when the brake lever is pulled and then released again as far as anything else on the +5V circuit is concerned.

If you can easily access the the red and black wires on the pedelec connection (or the unused wires on the motor harness if the pedelec connector is not fitted) it might be worth checking the voltage and seeing if it drops well below the original reading when the brakes are applied (which should have been ~5V with the brakes released).



If the ~5V drops noticeably, there is probably a fault (shorted wire or incorrect connection etc.) somewhere within the front harness that is causing your problem.

Make sure all of the individual unterminated wires are properly insulated when you have finished testing (lights, horn, pedelec and reverse).

Alan
 

[Ron]

Hi Alan,

Actually the regen was still not working in that video.  The brake lever on the right/throttle side is for the rear brake.  You can see the front brake pads in the video and they do not move.  Anyway that is irrelevant as I've found the source of ALL my issues, well bike issues anyway.

Both the  "Brake then immediate throttle = nothing on MP4" and "Magic Pie 4 regeneration not working" were caused by a faulty brake switch!  If I unplug the faulty brake and test with only the other brake lever all my issues are solved.  If I then take the good brake lever and plug it into the other 3 pin port of the wiring harness it works as well.  This leads to the conclusion that the right hand brake lever is bad.  The other symptom I notice is that when I activate the faulty brake lever the controller will issue a slight whine.  I assume this whine is caused by the 5 volt rail getting shorted out.   I'm sure Gary at GM Canada will be relieved to have this problem solved as we had sent controllers and finally the whole wheel back under warranty.    


I would like to thank Alan and everyone else for their help resolving this issue!

[Bikemad]

Well done Ron, I'm glad you've been able to locate the source of all your problems.

I never even gave the brake levers a second thought as the brake switches have always been connected by just two wires, and as your switches were cutting the power, I naturally assumed that the switches and their wires had to be working correctly:

The annoying thing is that it was only a few weeks ago that I spent some time checking out and recording all the connections on the MP4 harness:



This was when I discovered that there was an unused +5V supply to both of the brake switch connectors which is presumably ready to allow non-contact Hall effect brake switches to be used instead of mechanical contact brake switches:



The strange thing is that all of my recent MP4 and Smart Pie 4 brake switches still use mechanical switches that only requires two wires to operate correctly. I guess the additional wire is in the cable but just left disconnected at the switch end, but I suspect that in your case, the wrong wire has somehow been allowed to touch against the brake switch contact by mistake.

I hope you or Gary will be performing a Post Mortem, as it would be nice to know exactly what was causing the problem.

It all makes perfect sense now, and also confirms that my suspicions were absolutely correct, so although I was actually barking up the right tree, I was unfortunately focusing all my attention on the wrong branch  :

If this safety feature is triggered by the turning on of the +5V supply, I'm wondering whether there could be a problem within the front harness which is causing the brake switch to temporarily short out the +5V supply either in addition to (or instead of) the brake signal wire, which would effectively be turning off and on the +5V supply when the brake lever is pulled and then released again as far as anything else on the +5V circuit is concerned.

At least I was gradually heading in the right direction, and if you had tried the test I suggested, the fault would definitely have shown up.

Anyway, at least you've managed to solve both of the problems, and that's what really matters, and if this happens again to someone else, at least we now know what to suspect and also how to confirm it.

Alan
 

[Ron]

And it *only* took me 9.5 months to figure it out, LOL.


I doubt shipping it back to Gary would be worth it as the levers are not that expensive.  However I will take it apart once I get a new one.  I'm currently in the process if pulling apart my fried MP4 controller.  I can say that the conformal coating they use is quite good.  Pulling things apart I managed to rip some connectors off the board due to the adhesive properties of the coating.  I did notice 1/2 a resistor amongst the wreckage so I doubt I'll ever get it running again.  I know for sure that the two caps are both blown.  Anyway I'm way off topic and if I find the time I'll post some pictures on the controller parts.