Mystery box

[Allen Pippin]

I'm still trying to figure out why my 1999 prosport keeps frying it's cam sensor. I traced the wires back to a little metal box about 2" by 3" under the cover over the split tank. It has a plug that looks like you can plug a laptop into it. What is it ?

 

[Rottweiler]

Sounds like a thunderheart ignition module.
This takes the cam sensor input and sends output to the coil. They do go bad.
You might be able to replace with a new system like this. https://www.ebay.com/i/323374243381...C4Hm6aAcriJbf5JeXKJoKtyUO7fYPRDIaAoaEEALw_wcB

 

[HMAN]

Thunderheart used to test them. I sent them mine a few years back. Call and see if they will test it for you. May be a few $ ?.

 

[Jersey Big Mike]

Since the cam sensor is an INPUT to the Thunderheart it is unlikely that the Ignition module is damaging the cam sensor.
Over voltage and over heated are the two most common causes of cam sensor failure with what I've seen.

Have you checked the voltage on the bike with it running at speeds above idle? If so, is it over 14.4 v? Then its the VR /system.
Heat is a little harder to check but a decent non contact thermometer, or a DVM with a temp sensor will help -- use a small piece of kapton tape or something to use as a test point, if using non-contact option. Chrome/aluminum is to shiny and creates too much scatter often to get good results.

Given the time at which it fails from seeing other post, my vote sight unseen would be the voltage.

 

[Allen Pippin]

Since the cam sensor is an INPUT to the Thunderheart it is unlikely that the Ignition module is damaging the cam sensor.
Over voltage and over heated are the two most common causes of cam sensor failure with what I've seen.

Have you checked the voltage on the bike with it running at speeds above idle? If so, is it over 14.4 v? Then its the VR /system.
Heat is a little harder to check but a decent non contact thermometer, or a DVM with a temp sensor will help -- use a small piece of kapton tape or something to use as a test point, if using non-contact option. Chrome/aluminum is to shiny and creates too much scatter often to get good results.

Given the time at which it fails from seeing other post, my vote sight unseen would be the voltage.

I will have to install a new sensor to test the voltage. I will have to be quick before sensor failure. The EHC LED light does not light up while cranking. Is it because the sensor is bad ya think or is it bad ?

 

[Allen Pippin]

Since the cam sensor is an INPUT to the Thunderheart it is unlikely that the Ignition module is damaging the cam sensor.
Over voltage and over heated are the two most common causes of cam sensor failure with what I've seen.

Have you checked the voltage on the bike with it running at speeds above idle? If so, is it over 14.4 v? Then its the VR /system.
Heat is a little harder to check but a decent non contact thermometer, or a DVM with a temp sensor will help -- use a small piece of kapton tape or something to use as a test point, if using non-contact option. Chrome/aluminum is to shiny and creates too much scatter often to get good results.

Given the time at which it fails from seeing other post, my vote sight unseen would be the voltage.

I suspected the VR first but someone said probably not, but I will install a new sensor and quickly test voltage output before crashing

 

[Th3InfamousI]

I will have to install a new sensor to test the voltage. I will have to be quick before sensor failure. The EHC LED light does not light up while cranking. Is it because the sensor is bad ya think or is it bad ?

correct, if sensor fails it wont blink.

What exhaust you running on the bike? Does it run right there at the nose cone?

 

[Allen Pippin]

correct, if sensor fails it wont blink.

What exhaust you running on the bike? Does it run right there at the nose cone?

2 into 1 header from Big Dog ran great until it didn't

 

[Allen Pippin]

2 into 1 header from Big Dog ran great until it didn't

I rode to Sturgis last year from Wisconsin , it didn't miss a beat. I think my problems started when I tried to start the bike with a charger on boost. Every since then ,CRAP

 

[Jersey Big Mike]

I rode to Sturgis last year from Wisconsin , it didn't miss a beat. I think my problems started when I tried to start the bike with a charger on boost. Every since then ,CRAP

You can start the bike with the VR Disconnected. Trace the wires from the VR to the + terminal on the battery -- measure it while its disconnected. to be safe.