new sensor and still no spark!

[andyxlh]

Hello folks
I melted the nose cone sensor on my '96flhr, 80,000miles. I replaced it with a secondhand one and still no spark. I tried an earlier sensor from my '89xlh, and still no spark. Checked the wiring as per the manual (earth and shorts with an ohmmeter) and found nothing wrong. The resistance check of the module was OK, as was all the wiring loom checks in the manual. The coil has 12v input on the black and white wire. Tried to bypass the sensor as it suggests to get a spark by shorting across the BW and the GW feed from the sensor to the module, and check if the sensor was bad, and no spark suggesting sensor not the problem. Traced the wires under and around the bike, can't find any obvious problems.
I have not yet taken the tank off to check the pink wire to the coil as that is a pain in the backside, and the problem was originally the sensor. I have not got a ballast resistor setup to check the coil itself. How common is a failed coil? has anyone had this with the sensor at the same time? is there anything obvious that I am missing?
cheers
Andy

[Lew]

A bad coil is a possibility.  You can take resistance readings from the coil but they aren't always reliable.  I prefer to function test them.  You can check the coil with it still on the bike by first removing the sensor wire (and pink tach wire) from it.  Connect a points type condenser across both coil terminals.  Connect the condenser can to the coil terminal that had the ignition sensor and tach wires connected.  Connect the condenser lead to the the other coil terminal (positive feed from handlebar switch).  Pull one or both plugs and ground it/them to the bike.  Connect the plug/s to one/both plug wire/s.  Connect a wire to the coil terminal, that has the condenser can attached to it, to a bike ground.  Turn the ignition switch on.  Then switch the handlebar switch on and off several times while looking at the plug/s for spark.  The plug/s should fire if the coil is good.

[andyxlh]

Thanks Lew, I'll have to do that. I have a condenser can from an old car which I guess will do the job, and gets around the strange arrangement they suggest in the manual. Would be strange to have 2 failures at once - the sensor and the coil, I'm not sure how one could cause the other as the ignition module is between them? the failure was definitely temp related - failed when hot originally - but now nothing at all.
Many thanks again
Andy

[andyxlh]

sorted it - 2 failures, the nose cone and the coil - with both replaced it works!
how can that happen at the same time??

[FSG]

Andy things come in 3's so keep an eye out.   

[andyxlh]

hmm..... will make sure all the axle nuts are tight....
actually i did notice a weep from the front LH brake calliper, so I guess that's the next......

[smittyon66]

It's not really uncommon for one failed electrical component to take out another. Quite often, a bad stator will cause a regulator to take a crap.

[andyxlh]

yes, I could understand it for the sensor and the ign module, but the coil is separated by the module electrically i believe, so I would have thought they would be independent. clearly not!
BTW I have had the stator/reg one too......

[Diver625]

I ran into this on a trip several years ago. The engine quit, no spark, I pulled the nose cone cover and saw that the sensor looked burnt and replaced it. Still no spark, I replaced the coil, problem solved. When I got home I put the sensor back in and it still worked. If you have the time you may want to try your original sensor again just to see if it was bad or just looked bad.

[smittyon66]

I've seen sensors on late evo's that were melting but still running. Not a hint of trouble, just found it doing other work. It could have been a coil all along, but I still wouldn't depend on using that sensor much longer.

[andyxlh]

Yes I thought so... unfortunately I did a bit of 'exploratory surgery' on my old one - i wanted to see how the tilt sensor worked! So it certainly isn't going to work now. Anyhow, I agree, if it is melting it probably ain't going to go for much longer (old Injun proverb, perhaps?)