Wiring Diagram for T3, please.

[FlyingG]

Hi All, the wiring diagram is missing from my '76 T3-850 owner's manual (U.S. model). I searched for one here, but didn't come up with anything. Does someone have a link to one, por favor?

 

[Chris R]

Try Carl Allison's fantastic site:

http://www.thisoldtractor.com/guzzi007/sportissimo.html

I think the lemans/california/T3 from the same era are all in essence the same.

Thanks Carl and Greg Bender for all the info!

 

[GTM®]

Keeping it local, hosted on this server is the same by Carl (thanks Carl); https://www.guzzitech.com/guzzi007/sportissimo.html

 

[moto]

In front of me I've got an original 1975 T3 Owner's Manual open to the wiring diagram, U.S. version. It's essentially identical to the 1980 European T3 diagram by Carl Allison, here:

https://www.guzzitech.com/guzzi007/schematics/1980_T3_Europe.gif

The only difference I can spot is the presence of a "parking light," item 42, in the European version. This runs off the green wire supplying the headlights indicator bulb in the headlamp housing; your bike just omits the parking light along that circuit.

If my scanner were functioning, I'd scan the original for you, but the one at the URL above should work fine. You can also find both the US and European T3 diagrams in the back of the official Work Shop Manual, and the European version is also reproduced in the Haynes manual. (Strangely, the Haynes manual gives the key for the U.S. wiring diagram in a Figure 7.5, but the page holding that particular figure is omitted.)

The version at the back of the Owner's Manual is larger and crisper than the Workshop Manual's, and clearer than Carl's 1980 T3 diagram, at least at normal display sizes. I should scan it.

 

[FlyingG]

Thanks Gents. Maybe I won't have to push it again.

Looks like the ignition switch connector is corroded/disintegrating. Curious that this connector isn't on the diagram. It's an odd, round connector with little screws that secure the wires in place. It has Is it possible this is an aftermarket connector?

Cheers.

 

[Series4]

Doesn't sound standard to me. In an emergency you can hot wire the starter by applying momentary 12v direct to the spade terminal on the solenoid

 

[FlyingG]

Thanks, Series4 (great looking bike!). The starter circuit quit working ages ago. I've been jumping the starter terminals with a screwdriver for years until that quit working, too. Since this is my commuter bike, I've just been bump starting it laterly. It normally hits on the first lick, but when this electrical interruption occurs, it kills all power, even to the ignition. I hoped that cleaning the weird ignition switch connector would solve the problem - & maybe it has - but one odd symptom still remains: sometimes when I turn the key (a Kawasaki key, BTW) the lights come on about 1/2 brightness, but swtching it off/on again seems to bring them on at full strength. Wiggling the wiring doesn't seem to change this; before I could cause the power interruption by wiggling the connector wiring. The battery, cables & grounds are all good, so I guess it's just time for a full electrical overhaul.

 

[Rafael]

That LeMans does look great. Doesn't it?

FlyingG, The stock ignition key switch is still available at MG Cycles, http://www.mgcycle.com/product_info.php?products_id=761 you would need to change the wire connectors back to the original copperish individual bullet connectors. The orignial switch requires the stock metal switch housing that bolts to the top of the frame. I doubt you'll need a new wiring harness but it turns out you do that's available too. I recommend changing over to the Valeo starter, it requires less power to turn the motor, is stronger and doesn't chew up the ring gear. You can go with a inexpensive knock off or the real thing. The Valeo starter allows smaller battery, or a cheap low power lawn mower battery -size U-1, to be used. Have you checked the starter relay? The old metal housed unit tended to corrode after 10 years or so. A plastic sealed unit is cheap and available at most autoparts stores for $6. Get her back on the road!

 

[FlyingG]

Hi Rafael, thanks for the advice. It was at least 5 years ago, but I did check the starter relay & it was totally corroded up inside. I tried to use a Ducati relay, but when I changed handlebars I think something either broke or isn't making contact in the start button itself now. It always has so many problems (horns & turn signals quit working, dash lights mostly gone, butchered wiring everywhere) that I just sort of quit trying to fix it & just used a screwdriver to start it at the starter. I will get it going again, but I despise electrical problems & don't have tons of spare cash to spend. I'd like to do it right, so it may have to wait until winter.

 

[Carl Allison]

It sounds like you're do for a wiring overhaul or outright replacement. Depending upon where you're located, east coast, west coast, mid-west and so forth, there is likely someone on this forum that would be willing to help you rewire the bike since you're not fond of wiring. Modifying your profile to show your location would be helpful. If you're in Arizona, PM me.

Carl Allison - who thanks both Todd Eagan and Greg Bender for allowing him to host his numerous files on their servers.

 

[Carl Allison]

In front of me I've got an original 1975 T3 Owner's Manual open to the wiring diagram, U.S. version. It's essentially identical to the 1980 European T3 diagram by Carl Allison, here:

https://www.guzzitech.com/guzzi007/schematics/1980_T3_Europe.gif
<snip>
The version at the back of the Owner's Manual is larger and crisper than the Workshop Manual's, and clearer than Carl's 1980 T3 diagram, at least at normal display sizes. I should scan it.

The diagrams are size at double=normal size so that banded color wires are clearly legible. It works best on a 13x19" page if you want a good print at 72 dpi. If you're looking at it on your iPhone, I wouldn't expect too much. Try downloading the diagram printing it out. Generally, on my Macintrash, I can set the print size and the drawing will scale to my paper size by increasing the print resolution. I'm less certain about what Windows does but my experiences with Windows as far as printer drivers go is that there is all kinds of flexibility there for office documents but not much for graphics. If you have a version of Adobe Elements, that would probably be the best program to get the output on whatever printer you're using.

 

[FlyingG]

I want to thank everyone for generously sharing their knowledge & experience.

The power interuption kills both the lights & the ignition seemingly at the same time, so the problem would seem to lie somewhere between the battery + terminal & the ignition switch, because after that, the power goes to the ignition & the lights on separate circuits. Yes, could be a loose battery ground, too; but I've checked that. Will re-check, though.

Thanks again. Cheers.

 

[moto]

In front of me I've got an original 1975 T3 Owner's Manual open to the wiring diagram, U.S. version. It's essentially identical to the 1980 European T3 diagram by Carl Allison, here:

https://www.guzzitech.com/guzzi007/schematics/1980_T3_Europe.gif
<snip>
The version at the back of the Owner's Manual is larger and crisper than the Workshop Manual's, and clearer than Carl's 1980 T3 diagram, at least at normal display sizes. I should scan it.

The diagrams are size at double=normal size so that banded color wires are clearly legible. It works best on a 13x19" page if you want a good print at 72 dpi. If you're looking at it on your iPhone, I wouldn't expect too much. Try downloading the diagram printing it out. Generally, on my Macintrash, I can set the print size and the drawing will scale to my paper size by increasing the print resolution. I'm less certain about what Windows does but my experiences with Windows as far as printer drivers go is that there is all kinds of flexibility there for office documents but not much for graphics. If you have a version of Adobe Elements, that would probably be the best program to get the output on whatever printer you're using.

Carl,

First, thanks for all your GREAT diagrams. I had Kinko's print and laminate the Griso 1100 diagram, in color, and it's a beauty to behold. (It's a bit hard to store though, I probably shouldn't have laminated it.) My comment about the original diagram in the 1975 T3 Owner's Manual being clearer should have been put a little more clearly itself: It is only at the original size that it may be clearer, mostly because of the larger numbers chosen by the original draftsman.

I got my scanner to work again, and scanned the original diagram. Here is a smallish JPEG copy of it (less than 2MB as required by the "upload attachment" feature). (Click on it to see a larger version.) I wish I could post a better scan, at higher resolution.



[Edit:] And here is its key:



The original poster can now see the slight difference between this 1975 U.S. T3 and your 1980 European version.

Moto

 

[Rafael]

FlyingG, You can test the ignition switch by bypassing it, or hot wiring it. When my T-3 key ign switch started to fail, I pulled the bullet connectors from the back and bound them with a rubber band over a rubber finger cot - symptoms disappeared. That was my key 'till I got a new switch, just had to cap the hot lead when I took the rubber band off.
Also, check your fuse block for weak spring at the fuse holder.

If it turns out to be the ign switch, you can use a $5 rocker or toggle switch in its place, just have to hide it some where. I just did this to the Quota but it has a great big dash to hide it under until I rebuild the switch. You can also disconnect you right side controls for added security!

 

[FlyingG]

Thanks for the scan, Moto. I didn't know Motorcycle Consumer News was still in print

Thanks for the tip, Rafael. I might just do that to get back on the road. Cheers.

 

[Carl Allison]

Looks like I'll have to add a USA version of the T3 to the pile of diagrams. I'm going to have to go through all of the diagrams at some point as I shift from Canvas on the Macintrash to Canvas under Windows/VMWare on my newest Macintrash. Mostly, it's font issues but version 12 is very much different than the version 3.56 I prefer to use.

 

[moto]

Looks like I'll have to add a USA version of the T3 to the pile of diagrams.

Great! I was always puzzled by its absence.

I'll refrain from asking why "Macintrash," and esp. why Windows on a new "Macintrash." :shock: