Faulty light switch on GM throttle?

[Mr Powerful]

Hello!

I recently bought a GM Prokit 901 1000W 48V with a Ping 48V 20aH battery. Very pleased so far, and I've managed to fix niggles by myself. Except now, the lights stay on and the switch on the throttle doesn't do anything. The only way to get the lights to turn off is to flick my battery isolator switch.

I can only presume that there is a fault inside the throttle, but it is not clear how to open up the throttle to have a look inside. I didn't want to force anything or break stuff, so thought I'd ask here first.

Can anyone explain to me how to open up the throttle compartment to get at the light switch?

Thanks!

[Bikemad]

Hi andto the forum Mr P.

I presume you're referring to the front and rear LED lights being on all the time and not the battery gauge LEDs.
This simple way to check if the fault is in the switch (or wiring) on the throttle housing is to unplug the two pin plug on the other end of the throttle cable. If your lights are still on, the problem is not the throttle cable or switch.

Do you have the twist throttle or the thumb throttle?

Some of the GM kits had the throttle switch connected to control the reverse function of the motor instead of the lights, and the connector labelled for the LED lights was not fed through a switch (apart from the battery key switch).

Alan
 
 

[Mr Powerful]

Hi Alan, thanks for the help.

Yes, I was referring to the front and rear LED lights - sorry for not making that clear.

I am using the thumb throttle (having not got on so well with the full twist throttle).

So, I tried disconnecting the yellow and brown wires coming from the throttle housing (I already discovered the hard way that the yellow wire needs to be disconnected from the reverse terminal!!) at the controller housing end, and the lights go off. So then I tried removing the switch from the throttle housing (I worked out how to open the thing), after reconnecting the yellow and brown wires to the light wires. Lights on.

So I am guessing that there is a problem with the throttle cable.

What I didn't mention was that in trying to fix a different problem (front lights not going on, rear lights on - wiring problem) a couple of days ago, I accidentally touched the -ve wire to the +ve terminal on the light and sparks flew everywhere.  I'm worried that I may have damaged things in the wiring (and BMS?). Maybe I fried the throttle cable inside at some point along its length?

Are there any checks I can run for all the components - the BMS etc. - before I hit the road again?

[Bikemad]

I accidentally touched the -ve wire to the +ve terminal on the light and sparks flew everywhere.  I'm worried that I may have damaged things in the wiring (and BMS?). Maybe I fried the throttle cable inside at some point along its length?

Are there any checks I can run for all the components - the BMS etc. - before I hit the road again?

I would strongly recommend fitting a 1 Amp fuse into the lighting circuit for this very reason, and that it why I showed it in the lighting diagram:


Your battery should be fine because the thin lighting wires would have eventually fused completely at some point before the BMS would have been harmed. I think they probably got hot enough to melt through the insulation so they are now touching together somewhere inside the throttle cable. If your throttle and the battery gauge lights are still working, the other wires might still be OK.
A quick fix might be possible by connecting a short link as a lighting feed from the green wire connected to the battery gauge across to one side of the switch, and then connect both the brown and yellow wires to the other side of the switch and then disconnect the lighting feed completely (and insulate) and connect both the brown and yellow wires to the LED lights at the controller end.
Although this should work, I would not want to risk using that cable again because the insulation on the other cables may have also been damaged and the copper wires could eventually touch while the cable is flexed by the movement of the handlebars etc.

I would replace the entire length of the damaged six core cable just to be safe. You could either swap the cable over from the other throttle, or simply use a section of 8 core network cable if you don't want to dissect a good throttle and are unable to find a length of the correct 6 core cable.

Alan
 

[Mr Powerful]

Thanks. I'll go do some shopping.

Incidentally, the lighting diagram in my manual looks like this...

Yours looks more sensible.

I'm going to need a 40A fuse between the battery and controller as well, right?
These?
http://www.amazon.co.uk/gp/product/B007OUVZE4/
http://www.amazon.co.uk/gp/product/B000T6FIO8/

[Henry Chang]

Bring some pictures about front and rear LED lights (+horn) of  MP III  MP2 901(2)kits. Hope to help everyone.

[Mr Powerful]

So I simply replaced the throttle (and cable) with the full twist one and mounted the light switch on the controller housing (my new throttle has no light switch). All works fine now.

The new throttle (bought from bmsbattery.com http://www.bmsbattery.com/ebike-parts/119-wuxing-twist-grip-throttle-with-battery-meter.html) doesn't use the same colour code for the wires as Golden Motors.

BMS throttle     GM throttle
red wire            red wire (+)
green wire        white wire (throttle)
yellow wire       green wire (battery guage)
blue wire          black wire (-)

Just need to put in some fuses and I'm done!

[Mr Powerful]

ok, I spoke too soon.

Everything was working fine, until I mounted the front light on the bike and tried turning the lights on. And then kerpow! More sparks.

Why does it do this???

[Bikemad]

Unfortunately, this happened because one of the lights is probably connected incorrectly and the connections on the LED lights are not isolated from their fixing brackets. 

If you wired the front light as per the original diagram that you posted, it would not have worked, so I'm assuming you must have connected it as per my modified diagram, ensuring the negative connection would also connect to the frame of the bike through the fixing bracket when fitted.

I'm guessing that you did not wire the rear light as per my diagram, because the right hand fixing bolt on the rear light is also connected to the right hand wire connection, so if you incorrectly connected the positive wire to the right hand connection, it would also connect to the frame when fitted.
As the frame is also connected directly to the ground connection on the front light, this would obviously cause a direct short circuit through the metal frame itself, hence the sparks! 

The diagram looks great. Now if we can get Yao Yaun to replace the diagram in the instalation guide with this one we could save people some problems. I burned out the switch in my thumb trottle using the original diagram. I know its an obvious error if you take the time to look at the grounds on both lights, but I just blindly followed the instructions in the guide thinking they must be correct.

Unfortunately Yao is the only person who has access to edit the manual to insert the corrected diagram, but it appears that this still has not yet been done almost 29 months later!

Alan
 

[Mr Powerful]

Thanks for the heads up about the wiring diagram error Alan. I forwarded your (correct) one to my retailer (devi motion in the Netherlands). I expect nothing will happen though.

It should be made clearer which is the positive and which is the negative terminals on the lights. On the front, it is kind of obvious because the negative terminal is visibly connected to the frame of the bike, but on the rear, it's not at all obvious.

Given the potential damage that could be caused by incorrect wiring, it's something that should be taken a bit more seriously!!

Anyway, all is working properly now and I'm back on the road.

Thanks for your help. Great forum!