98 EV Regulator/Rectifier Troubleshooting/ Replacement


My 98 EV wasn't showing the battery charge light, but it wasn't charging the battery at all.  The charge light did NOT come on when the ignition was in the on position, prior to starting the bike up.  The voltage across the battery terminals was the same through any RPM, including on with the engine stopped.  Assuming the voltage regulator/rectifier was bad, I ordered the new aftermarket Electrex part (RR51) from denniskirk.com for $165.  OEM was $202 at the dealership.

As soon as I took the old Reg/Rec off, I realized that three of the wires were unplugged.  The only thing remaining (and plugged in) was the two-lead wire to the alternator. Here's what I had to do to find the other end of the wires that were unplugged.  Steps would be the same for replacement of the Reg/Rec.

1.  Remove the Reg/Rec using the two bolts that hold on the horns.

2.  Remove the Reg/Reg mounting plate by loosening the top bolts on the crash bar.  Don't remove these all the way or the metal plate will fall off the back of the bolts.  The mounting plate will slide down and free once the bolts are loose.

3.  Remove the left side chrome trim plate that sits in front of the gas tank.
     ********* NOTE:  If you trace the wire up from your side stand relay, you can pull apart the connection under this trim plate to disconnect the side stand relay.******************

4.  Remove the gas tank bolt under the seat and pull the gas tank up and back to make room to work up front.  This may not be necessary but makes things easier, and it's only one bolt.
The wire ends were zip-tied to the inside of the flat, black, frame gusset at the top front corner of the frame.

5.  Cut the zip-ties that hold the wires in place, and pull the wires out where you can see them.

6.  Run the Reg/Rec wires through the front of the frame to the location of the newly found wires.  Plug them in and tuck them back into the frame.

7.  Plug in the alternator wires.

8.  Reassemble.  Charging problems solved, no more side stand relay.

This was the first time I worked on my Guzzi, and this repair took me only about an hour, most of which was spent trying to find those wires. 
Total tools - 2 Allen wrenches and a pair of small wire cutters.  Removed 5 bolts and loosened 2.

There is a very good charging system diagnosis tool at
<http://www.electrexusa.com/electrex_fault_finding.html>.  If I had followed this before ordering the replacement part, it would have told me that I had a bad connection in the positive battery terminal lead.  There is also a wiring diagram and installation instructions for this Reg/Rec at <http://www.electrexusa.com/Images/RR51_INSTRUCTIONS.pdf>.

BTW - this is the newer, single phase, Ducati style Reg/Rec - not the older three-phase Bosch model.

Best of luck,

Matt
MatthewFunk@hotmail.com