750 Paso Wiring Upgrade to Improve Starting

Post by **jcslocum** » Fri Jul 15, 2005 11:31 am

The original wiring upgrade was to fix the starting problem that I had with my Paso. It just wouldn't crank properly. The fact that it also solves many other problems is just a bonus. Once I dug into it and found that all of the connecions and the fact that all of the electric runs thru the switch I then understood just how easliy this could be fixed.

These mods look very stock and don't take a lot of skill ( Skins did it!) and I like the keep it simple approach. I do love working on my bikes but riding them is even more fun.

Luca, get that bike on the road and ride it, there's always time to do incremental upgrades.

jfiore · Post by **jfiore** » Fri Jul 15, 2005 4:24 pm

Just to answer the question about the installation of a diode across the relay coil - If you purchase Bosch automotive relays, they are made with a suppression diode connected inside the relay body. Connecting another diode externally to the relay would be unnecessary, but would do no harm. If an unknown type of relay is used, then connection of a suppression diode is a necessity. Just make sure that the diode is connected with the correct polarity, as descrived in the previous post, or the relay will never work (and the diode may burn up!).

Post by **Skins** » Sat Jul 16, 2005 8:00 pm

Hey! I can't be that silly - I bought Bosch.

lceriani · Post by **lceriani** » Sun Jul 17, 2005 10:05 am

jcslocum,
yours is great wisdom! effectively with such beatufil sunny days here in Italy is a pity to keep the bike on the garage so... I think I'll apply the wiring redesign this winter! For now I'll just mount the main power realy.

Bye and thanks!!!

LC

PS: not every bosch (mini)relais has a diode insiede, but only these models:
0 332 019 109
0 332 019 155
0 332 209 109
0 332 209 152
0 332 209 158
datasheets available if necessary!

lceriani · Post by **lceriani** » Sun Jul 17, 2005 10:09 am

ehmmm.... just a little problem....
I mounted the main power relay upgrade and it seems to work: turn on the key = relay on, voltage on battery much more constant and always between 12 and 13,9 V, now lights and turning signals works even with engine off...

BUT

when I run I cotinuously blow the 7.5 A fuse connected to the green/black line!
Mmmm.........

LC

Paul · Post by **Paul** » Mon Jul 18, 2005 4:50 am

Jon,

I looked up the conversion for 14 swg and 12 swg to metric. The 14 swg is 1.62mm and the 12 swg is 2.05mm.

Is there a reason why you used 14 swg for some areas ?

Would it be OK to use 2mm for everything, or would you suggest using slightly thinner for the areas you used 14 swg ?

Thanks

Paul

lceriani · Post by **lceriani** » Mon Jul 18, 2005 7:53 am

I discovered the reason of the blown fuses!
There's an error in the schematics taken from my shop manual.

Here's the schematics:

as you see it's indicated a 7.5A fuse for the G-BK line.

Here's the shop manual:

as you see, the same fuse (F2) is 15A !

Obviously the right value is 15A.

LC

Paul · Post by **Paul** » Mon Jul 18, 2005 7:57 am

Luca,

Was it a 7.5A before you changed the wiring ? or did you change all the fuses atthe same time ?

Paul

lceriani · Post by **lceriani** » Mon Jul 18, 2005 8:05 am

It could be 15A but I am not sure: when I checked the resistance of the lines I detached all the fuses and replaced them following the schematics indications...
(what a mistake!)

LC

Paul · Post by **Paul** » Mon Jul 18, 2005 8:07 am

I will have a look at mine when I get home tonight and let you know what I have. Mine is an '87 model.

Paul

motiztab · Post by **motiztab** » Mon Jul 18, 2005 11:01 pm

Ok I have already done the coil wiring mod and tonight did the main relay one not that I had a starting problem more of a dimming head light when using the indicators, not good at night!

Anyway why is there a 7.5amp fuse? Connected to an orange wire, which if you trace it back to the connecting block under the fuel tank is not connected to anything?

Post by **jcslocum** » Tue Jul 19, 2005 1:28 am

motiztab wrote:Anyway why is there a 7.5amp fuse? Connected to an orange wire, which if you trace it back to the connecting block under the fuel tank is not connected to anything?

It's listed as a spare. The mysteries of Italian wiring!!!

You ride your Paso at night!?! Brave Man.....

Paul · Post by **Paul** » Tue Jul 19, 2005 4:32 am

Luca,

My fuse block can take six fuses. If you number them as number 1 being closest to the fuel tank and number 6 as being closest to the tail light, this is what I have in them :

1 - 7.5 A (spare)
2 - 7.5 A
3 - 25 A
4 - 25 A
5 - Empty
6 - 25 A (spare)

If the number 3 and 4 above should be 15A it looks like my 25A fuses are not really protecting anything. I will put some 15A in this weekend (and take the 25A with me just in case).

Paul

motiztab · Post by **motiztab** » Tue Jul 19, 2005 10:21 am

Riding at night is interesting!! and round here we have deer/ponies/cows on the road if over in the New Forest.

lceriani · Post by **lceriani** » Tue Jul 19, 2005 2:07 pm

Paul,
thanks for the check. Excluding spares, it seems that you have 25A fuses instead of 15A, but their use is the same as in the office manual: 2 "big" (15/25A) and 1 "small" (7,5A), not viceversa.
Definitively, your check confirms that the schematics has an error...

750 Paso Wiring Upgrade to Improve Starting

Wiring Mod.