CDI Box/Ignition ECU making loud *ZAPP* noise at ignition

Hey guys, so I've been scouring through previous posts to try and make sure that I wasn't asking an already-answered question, but I haven't been able to find exactly what I need. So here is the situation in a nut shell:

I hauled my bike to riding area last weekend and it was pretty chilly out (~40 F). Got the bike unloaded and went through normal engine start procedure. I turned the key, made sure the kill switch was off/down, heard the fuel pump whine, pressed in the ignition button and the bike cranked a few times but didn't start. Let it sit for a few seconds, figuring it was just cold, and pressed the ignition button again and I heard an audible ZAPP (like when you touch two battery leads together) and then lost all electrical power. The LCD screen went blank, the lights turned off, and the everything went dead. I turned the key off, and then back on, and all the normal electrical stuff came back on, and the fuel pump primed, so I pressed the ignition switch again and the bike fired up. Rode the rest of the afternoon with no trouble and the bike ran as it should. I turned off the bike a few times and turned it back on throughout the afternoon with no issues, until I got back to the truck and it did it once more (same sequence of events as when I first tried to start the bike; complete electrical power loss, turned the key off and then back on and then it fired up).

Got the bike home and started investigating the cause. All the lights come on and work as they should, including blinkers, brake lights as well as high and low beams. Bike started up just fine a few times in the garage without a repeat of the sudden electrical power loss at ignition.

My initial thoughts:
1) I figured I had a wire that was shorting out somewhere, and I suspected it was under my Tusk luggage rack on the tail of the bike. I removed the rack, checked the wiring harness and saw that part of one of the wires going back to the tail lights was pinched, so I inspected the wires and luckily didn't see any wire damage, and it was just the rubber sleeve that had been pinched. I moved it, wrapped the harness with electrical tape, and zip tied it out of the way.
2) I checked the connections on the battery terminals and they were loose (I could wiggle the wires with my hand easily and they would rotate on the post) so I tightened them down snug and made sure there wasn't any free play at the terminal.

Since tightening the connections at the terminal, I have not had any more issues with loosing electrical power at ignition, and Im 99% sure that was my issue. HOWEVER, since I had the seat off and the panels off, I could easily see and hear the CDI Box/Ignition ECU towards the tail end of the bike, and when I go through the normal engine starting process, that box makes a pretty loud zapp noise every time that I press the ignition button.

I called the dealership that I bought the bike from and asked them about the noise and the rep said it was normal. But I don't recall ever being able to hear a spark/zapp noise coming from the CDI box before the power loss events, and now I am concerned that I may have damaged the CDI box during the power loss events. OR I may just be being hyper sensitive to the whole thing now and worrying about it. Granted, I don't think I had ever started my bike with the seat off before this whole thing, but now I know what it sounds like and I can hear it with the seat back on.

Im really sorry about the long post, but Im hoping that you guys can give me some advice/reassurance that the CDI Box does in fact make an audible electrical zapp sound at ignition, OR that it is unusual and should not make any loud zapp noise, and that I should take it to the dealership before my warranty is up.

Thanks is advance for the info!

I attached a picture of the CDI Box for clarification of what I am referring to.

Well at the moment I can't comment on the CDI box noise but I can tell you a loose cable connection at the battery can sound like a short at times.

Thanks, Bob. I was really hoping that after getting the connections tight on the terminals of the battery that I wouldn't hear any more zapping sounds, but it still prevails.

KansasZach wrote:

Thanks, Bob. I was really hoping that after getting the connections tight on the terminals of the battery that I wouldn't hear any more zapping sounds, but it still prevails.

I will be going over mine this coming weekend for a ride out in Tellico Plains. I will give a listen and see what I hear - although I am deaf in one ear and the other works ok.. more like selective hearing.

rsteiger wrote:

KansasZach wrote:

Thanks, Bob. I was really hoping that after getting the connections tight on the terminals of the battery that I wouldn't hear any more zapping sounds, but it still prevails.

I will be going over mine this coming weekend for a ride out in Tellico Plains.  I will give a listen and see what I hear - although I am deaf in one ear and the other works ok.. more like selective hearing.

I sure appreciate it! I have a feeling I might just be being worried over nothing. I could probably benefit from some selective hearing myself.

There is nothing inside the ECU what could make a zapp sound, nor the ecu could cause power loss (short cut) without burning a fuse or itself. Inside the ECU, there is only electronics, no relays. Relays are near the battery.
I'd advise to check the connector on the right side in front of the tank. Main power supply to the ignition switch goes through this connector and this happened to me, once during riding I switched the bike off, then on and nothing happened. Then I turned the handlebars and the bike came alive.
Anyway, check the connectors, clean them, apply some cleaning spray. That’s a way how to start.

If this ZAP noise happens when you press the start button, I'd wonder if it's actually coming from the starter relay.
The starter relay is the thing the battery's positive lead runs to.
It is normal to hear noise from this relay when pushing the start button because it is a relay that uses the small electrical current from the start button to control the much larger electrical current from your battery to the starter motor.

klubko wrote:

There is nothing inside the ECU what could make a zapp sound, nor the ecu could cause power loss (short cut) without burning a fuse or itself. Inside the ECU, there is only electronics, no relays. Relays are near the battery.
I'd advise to check the connector on the right side in front of the tank. Main power supply to the ignition switch goes through this connector and this happened to me, once during riding I switched the bike off, then on and nothing happened. Then I turned the handlebars and the bike came alive.
Anyway, check the connectors, clean them, apply some cleaning spray. That’s a way how to start.

Thanks for the advice Klubko. Ill definitely take a look at that area and investigate those connectors. Are they pretty easy to see/identify? Should I just trace the wire from the ignition switch to get me there?

YZEtc wrote:

If this ZAP noise happens when you press the start button, I'd wonder if it's actually coming from the starter relay.
The starter relay is the thing the battery's positive lead runs to.
It is normal to hear noise from this relay when pushing the start button because it is a relay that uses the small electrical current from the start button to control the much larger electrical current from your battery to the starter motor.

Thanks a bunch YZEtc, i'll have to give it another listen and see if I am misdiagnosing the location of the sound at ignition. From what I've read so far, it sounds like it can't be the ECU module because of its design, so logically it has to be coming from somewhere else. And if I really did fry the ECU some how or damage it, I don't think I'd be able to get my bike to start at all and it has been starting just fine.
Gotta love electrical gremlins!

Update:
After reading the advice from other folks, I gave listening to the problem area another try. Lo and behold, it definitely WAS NOT coming from the CDI box. I put my ear close to the battery and it was definitely coming from the starter motor. The bike starts up with no issue since I tightened the screws on the battery terminal and I think I can confidently chalk this one up to being worried over nothing. Lesson learned.