How do you know if your TCI is blown?

I installed a "new" wiring harness off a working bike. The old one was spliced a reworked by the previous owner( when you step on the brakes the front turn signal turned on, no headlight,Etc..) I double checked all my grounds and connections. When I when to first fire it up. I heard a "pop" from where the TCI is. I am pretty sure that it"s toast. All the lights work, the ignition tries to turn over, but no spark. The only questionable wiring would be the 3 white wires going to the generator. The old wire harness melted the connector when I hooked it up to my car battery to crank her over. Does anyone know if there is a certain order for the 3 wires. My bookis no help(Haynes manuel) the more important thing I don't what to burn the new TCI out. Any suggestions?

 

You know it's not recommended to jump start your bike from a car? I've done it successfully, but it sounds like you learnt the hard way that it's not a good idea.

 

You will need to proceed carefully! check the wiring carefully to and from the TCI connector to make sure it is good. Your Haynes manual should help you do this.

There is no set order for the 3 white wires from the alternator - they have their other ends connected together internally in a "Star" configuration (called "Wye" in the US.)

Check you actually have 12v getting to the TCI before you condem it - You need a multimeter with DC volts and Ohms (Resistance) to fault find effectively.

Lastly - put your location and bike model in your signature - it will help others help you.

 

i don't have the car running. but i've been known to jump start from a car.

the bike will only pull the amps it needs. the car DOESN'T push the amps it don't need.

the big clamps do make it hard to connect to a bike though. LOL.

the 3 white wires are from the alternator. 3 phase alternator, thus 3 white wires. one wire to one coil winding in the alternator. they all do the same job. which is send alternating current (AC) to the regulator/recitifier unit where it's converted to DC volts. all 3 wires do it at different times. they don't all send at the same time. it just has to hit the recitifier to be converted.

in theory it probably wouldn't matter what position the wires are on the plug. practicality wise might be a different story.

 

It's my understanding that the much more powerful car alternator jumps the voltage up high enough to damage the bike's electronics as it's trying to recharge the smaller bike battery.

 

I think he's saying that the car engine was NOT running, This is OK.

 

Ok Folks, here it is again. You can safey start a bike off of a car battery. It is a VERY bad idea to hook up to a running car, this will likely spike your ignition unit. As Snowwy mentioned, the car won't push amperage, but the bike with the dead/weak battery will cause a jump in current when connected and since the car's alternator sees this as a load, it will ramp up current output. This "spike" can be well beyond the bike's rated capacities and will take out the more sensitive parts of the ignition system (the TCI being formost on the list). Remember, our XJ's alternators are rated at about 19 amps (for the 650/750 line), most car alternators are 35 amps and up.
The alternator output connections (those three wires that formerly inhabited that melted connector) do not need to be in any particular order, just plug them in and go. The rectifier will sort it out just fine in what-ever order you end up with.

 

I fried the harnass a while ago a replaced it with some bullets. The bike has run fine for months. This had nothing to do with my current problem of possibly having a blown TCI. How do you test the rectifier? I am not certain my problem is the TCI. The "pop" came from that area. The wiring harness I got has been un-modified except for a new fuse box.

1980 XJ650
New rings
Lapped valves
New gaskets

 

To test the rectifier, follow the instructions in the Haynes (it is actually pretty good IMHO and the specs are accurate). Short of that requires a running machine. You would read the voltage output at the battery with the bike at idle, typically just below static (12 volts or so but 11.5 isn't unreasonable). Run up the rpms to 2,500 and see if the voltage has increased to around 14 volts (or thereabouts, I don't have my manual in hand), 13.5 should be a minimum I think (someone with a book help me out here please). The point is that you should see a 1.5 to 2 volt jump in the voltage of the battery around 2500 rpm.
I'm hoping you didn't fry your TCI, what a pain that must be. Are you certain that you didn't hear a pop from the airbox located just behind the rectifier panel?