Help me identify this part. Picture included

[duanelr]

Under the seat, behind the battery, and zip-tied to the frame. I have my finger on the part in question.
What does it do?

[FJ_Hooligan]

Looks like an aftermarket light modulator. 

Does your headlight or taillight flash?

[CutterBill]

That's the diode block.

And what year is your bike?
Bill

[Pat Conlon]

Bill...it's in his sig line...'87

[duanelr]

That's the diode block.

And what year is your bike?
Bill

Thank you. As Pat wrote, I have an '87.
Ahhh, there are diodes in there. It's such an unusual looking part and seemingly just squeezed under the frame.
Do you know what aspect of the bike they are used for? (I ask only out of curiosity).

[Pat Conlon]

Duane, FYI Bill Cutter created a bitchen current flow diagram to help us understand the logic of the FJ's wiring harness. If I understand the nomenclature correctly, I see some diodes on the clutch safety switch circuit. Diodes keeping the current flowing one way, preventing backfeed.

Even though this diagram is for the Gen 4 FJ's ('91-93) I would expect to see the same diodes on your '87.
Bill is working on current flow diagrams for the earlier 3 generations of FJ's.




http://www.fjowners.com/index.php?topic=18991.msg192459#msg192459

[CutterBill]

...If I understand the nomenclature correctly, I see some diodes on the clutch safety switch circuit. Diodes keeping the current flowing one way, preventing backfeed.

True. There is also one diode for testing the oil pressure warning light when the starter button is pushed.

Even though this diagram is for the Gen 4 FJ's ('91-93) I would expect to see the same diodes on your '87.

Also true.

...Bill is working on current flow diagrams for the earlier 3 generations of FJ's.

Yep. The 84-85 diagram will be easy. The others will be horrible. I'll need to copy and print those crappy Yamaha drawings as large as possible just so I can highlight the wires as I go. Give me time...
Bill

[Pat Conlon]

Thank you for doing this Bill. Breakfast is on me at the next FJ Rally.