Riddle me this..

[Tubolove]

New to me 2002 Big Dog Bulldog. Speedometer is not working so I thought I would start with a new speedometer sensor. I saw that it was a Thunderheart module that the speedometer plugged into so I ordered a replacement Thunderheart speed sensor. The speed sensor I received looks identical in every way except the wires are thinner and the plug has female terminals inside instead of male terminals and the wires are in a different orientation. Since the wires were in a different orientation and would be female to female on the bike I cut off the plug and wire them red to red green to green and black to black however with the new speedometer sensor installed the bike will not start or run. If I plug in the old speedometer sensor the bike starts and runs perfectly but the speedometer doesn’t work. Should I try and splice in the new speed sensor in the orientation the colors came from the factory?

 

[Mr. Wright]

Doesn't make sense. Red is 12v , black is ground, and the green is the signal wire, on all units I've seen.

 

[Tubolove]

Doesn't make sense. Red is 12v , black is ground, and the green is the signal wire, on all units I've seen.

Makes no sense right?!? And why would it not run? As soon as I unplug it it starts right up.

 

[Jersey Big Mike]

Get out the multimeter and test the new unit for a short (disconnect battery first)

 

[Sven]

You can take the meter and match resistances - wire for wire. For arg-sake, say black reads 3 on the new sensor, and green reads 3 on the old sensor. Red and red read 1. So now you ignore colors and match resistances. So jobber wise, you are not creating a magnetic field with hot only. It takes a ground wire to complete the circuit to ground. The 3rd wire out is sending a signal.

I mean, at this point, you just swap the two wires. Red is hot off the main harness so assume red is wired the same at both sensors. Or, you are back to swapping red twice with the other two combinations. If red is not wired for hot, what [of the] two is the hot wire?

Obviously you made just one move to start the bike. You'd assume it's the one wire swap. Another arg-sake is using this as a 3-wire jobber(sensor). The gate diagram acts the 3 wire speed sensor. So in the body [just using this as an example only] is the job of making magnetism. A is hot, B is ground, C is signal out to speedo.

 

[Tubolove]

Thank you. I will get in there and play around with it today. What I’m terrified of is how everyone says electronics on these are just awful and what I don’t want to short out anything on the EHC by flopping wires around incorrectly. I think I’ll do what I can with a multimeter before powering up the bike to confirm everything.

 

[Tubolove]

I’m only posting in case this helps someone else so you can flame me if you want to.

Turns out the old speedometer sensor isn’t bad and neither is the new speedometer sensor.

Still haven’t figured out the speedo not working issue but i’m embarrassed to say the no start issue is yours truly.

Turns out big dog uses the same exact plug on the cam sensor as they do on a speedometer sensor.

Probably the reason for the different size wires, wire orientation, and the female terminals is so a dumb ass like me won’t plug a speedo sensor into the cam sensor plug.

Anyway… Back to Speedo diagnosis.


Sent from my iPhone using Tapatalk

 

[Th3InfamousI]

I’m only posting in case this helps someone else so you can flame me if you want to.

Turns out the old speedometer sensor isn’t bad and neither is the new speedometer sensor.

Still haven’t figured out the speedo not working issue but i’m embarrassed to say the no start issue is yours truly.

Turns out big dog uses the same exact plug on the cam sensor as they do on a speedometer sensor.

Probably the reason for the different size wires, wire orientation, and the female terminals is so a dumb ass like me won’t plug a speedo sensor into the cam sensor plug.

Anyway… Back to Speedo diagnosis.


Sent from my iPhone using Tapatalk

That would do it! At least you fessed up! Best part is you WONT do that again! haha

I read this earlier and didn't want to say anything but thought maybe that's what you did..lol

 

[mchllacey]

If you have a speedo that's made by auto meter you may have a broken wire on the back of the circuit board in the speedo. I have an 06 K-9 I just changed out and was corroded badly on the circuit board. Several people including myself have taken them apart and soldered a broken wire.

 

[Tubolove]

If you have a speedo that's made by auto meter you may have a broken wire on the back of the circuit board in the speedo. I have an 06 K-9 I just changed out and was corroded badly on the circuit board. Several people including myself have taken them apart and soldered a broken wire.

VDO....