Relay Failures, Why They Fail and How to Fix by David Laing.

V11 Relay Failures, Why They Fail and How to Fix by David Laing.

  I discovered the cause of some of the relay failures on the early V11 six speeds. This presumably effects 1999, 2000, and possibly some 2001 models that have the loose relay blocks. According to the 2001 Owner's Manual the wiring diagram indicates that the problem was fixed.

  About two years ago I replaced the relays on my bike with the grey Bosch units. Over the past month or two they started to fail. I ordered a new set from Dan Prunuske, and he took interest as to why the relay failed so I decided to investigate the cause. Looking at the wiring diagram on Carl Allison's site and looking at the specs on the relays, I realized that the current of the headlight and a few other current using devices passed through a 10 amp rated section of the relay!!!!
Drat! The Guzzi Engineers made a mistake!!!! But being an electrical layman, I was not completely sure, so I emailed
a reply to Dan, and he agreed that there is a problem.

Dan's reply/post:
David Laing recently contacted me regarding a failed Bosch starter relay on his V11 Sport. He thought the problem was that the Normally Closed terminal of the starter relay powered the headlights, not merely the coil of the headlight relay. I was skeptical (who would be so stupid?), but after checking the wiring diagram, he is correct. Worse, that terminal (rated at 10 amps) also powers the brake lights, the tach, the horn, some of the instrument lights, and is the reference voltage for the GEN lite! Arrrrgh. The high beam and the brake lights alone are about 9 amps, and IMHO, too much load on a 10 amp contact. (My normal rule of thumb is to use a relay capable of twice the anticipated load).

No doubt there are other improvements that could be made to the wiring layout. For example, you might want to get at least the brake lights out of the headlight circuit. Obviously people are getting by with the wiring done as Guzzi layed it
out. It took David Laing about 15,000 miles for the Bosch relay to fail, and some have lasted longer. But if you want a reliable machine, We recommend doing one of the following modifications.

What to do? I'd suggest:

1. Do some rewiring and add additional relays to spread the load.Dan and I tried unsuccessfully to come up with some simple and effective re-wirings, but to do it properly, you would need to add one or two more relays to get the load off of the 10 amp relay contacts.

2. Just replace the starter relay with a higher Amp rated relay.We still recommend the Bosch for the other relays as it has proven to be durable.

  The Bosch that Dan has been selling is rated at 20 amps at the 87 terminal and 10Amps at the 87a terminal.
For the 'starter relay' we need a higher amp rating at the 87a terminal(Normally Closed terminal). There are many options available in larger relays, but we want one that will fit without rewiring. Dan and I searched the internet for the right relay and came up with the GEI AR4 relay. It is rated at 25Amps at the 87 terminal and 20 amps at the 87a
terminal and best of all it fits!

The only question now is: How long well it last?

Dan sent me a test unit, so I shall be testing it and hoping to have feed back by early 2004. At that point Dan should be able to order a bunch to sell to the Guzzi public.

If you have a later model this problem is not as critical, but it appears that the starter solenoid still places a strong draw on the starter relay and other wiring. A better solution for the later models is to dedicate an additional 30A relay fused at 15A going directly from the battery to the starter solenoid.

The V11 five speeds do not seem to have these wiring flaws, but also have a strong draw from the starter.