• Ciao Guest - You’ve landed at the ultimate Guzzi site. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER - Use the CONTACT above if you need help. New to the forum? For all new members, we require ONE post in the Introductions section at the bottom, in order to post in most of the other sections. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have, have likely been already answered. DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back in and reply within 24 hours, or your post will be deleted. Note there's decades of heavily experienced Guzzi professionals on this site, all whom happily give endless amounts of their VALUABLE time for free; BE COURTEOUS AND RESPECTFUL!
  • There is ZERO tolerance on personal attacks and ANY HYPERLINKS to PRODUCT(S) or other competing website(s), including personal pages, social media or other Forums. This ALSO INCLUDES ECU DIAGnostic software, questions and mapping. We work very hard to offer commercially supported products and to keep info relevant here. First offense is a note, second is a warning, third time will get you banned from the site. We don't have the time to chase repeat (and ignorant) offenders. This is NOT a social media platform; It's an ad-free, privately funded website, in small help with user donations. Be sure to see the GTM STORE link above; ALL product purchases help support the site, or you can upgrade your Forum profile or DONATE via the link above.
  • Be sure to see the GTM STORE link also above for our 700+ product inventory, including OEM parts and many of our 100% Made-in-SoCal-USA GTM products and engine kits. In SoCal? Click the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work, and don't miss our GT MotoCycles® (not) art on the BUILDS tab above. WE'RE HERE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED - DO NOT EMAIL AND ASK QUESTIONS OR ASK TO CALL YOU.
  • Like the new V100, GuzziTech is full throttle into the future! We're now running on an all-new server and we've updated our Forum software. The visual differences are obvious, but hopefully you'll notice the super-fast speed. If you notice any glitches or have any issues, please post on the Site Support section at the bottom. If you haven't yet, please upgrade your account which is covered in the Site Support section or via the DONATE tab above, which gives you full site access including the DOWNLOADS section. We really appreciate every $ and your support to keep this site ad-free. Create an account, sign in, upgrade your account, and enjoy. See you on the road in 2024.

2014 V7 ECU Dead short

DETRoadster

Tuned and Synch'ed
GT Contributor
Joined
Nov 5, 2018
Messages
72
Location
Seattle
Hi Fellas, hoping someone can give me some advice. On my last ride I was flying along the freeway at 70MPH, enjoying the sweet sweet sounds of my GTM 2 into 1 exhaust. Suddenly and without any warning the bike just died. No cough, no sputter, just flat shut off. Towed it home and begun the diagnosis. Here's what I've found:

The 5 amp fuse to the ECU is blown. Put another 5 amp in and it immediately blew, with the bike off (key not even in it). Consulted the wiring diagram and it looks like that fuse gets 12VDC from the voltage regulator. Checked that side of the fuse and sure enough there's continuity to battery +. The downstream side of the fuse goes to a pull-up resistor and to the ECU. This side of the fuse is shorted straight to chassis ground. Doh! Pulled the main ECU connector and the short to ground goes away. Soooooo, blown ECU with internal short to ground?
 
Hi Fellas, hoping someone can give me some advice. On my last ride I was flying along the freeway at 70MPH, enjoying the sweet sweet sounds of my GTM 2 into 1 exhaust. Suddenly and without any warning the bike just died. No cough, no sputter, just flat shut off. Towed it home and begun the diagnosis. Here's what I've found:

The 5 amp fuse to the ECU is blown. Put another 5 amp in and it immediately blew, with the bike off (key not even in it). Consulted the wiring diagram and it looks like that fuse gets 12VDC from the voltage regulator. Checked that side of the fuse and sure enough there's continuity to battery +. The downstream side of the fuse goes to a pull-up resistor and to the ECU. This side of the fuse is shorted straight to chassis ground. Doh! Pulled the main ECU connector and the short to ground goes away. Soooooo, blown ECU with internal short to ground?
Bummer. No on the ECU. They are surprisingly stable. You have a simple short somewhere in the harness. Trace the wires to/from the fuse. You can also start in the ignition switch. That has proven to be a weak link. Post on what you find.
 
Bummer. No on the ECU. They are surprisingly stable. You have a simple short somewhere in the harness. Trace the wires to/from the fuse. You can also start in the ignition switch. That has proven to be a weak link. Post on what you find.
Thanks Todd! I'll ring it out with the multimeter and see what I get.
 
OK, so the suspect wires from the fuse disappear into the harness and emerge at the ECU connector. Somewhere in between is the short. Any suggestions, aside from pulling the entire harness, unwraping, and inspecting? Is it kosher to clip the offending circuit by the fuse and again by the ECU connector and simply connect with a new wire?
 
OK, so the suspect wires from the fuse disappear into the harness and emerge at the ECU connector. Somewhere in between is the short. Any suggestions, aside from pulling the entire harness, unwraping, and inspecting? Is it kosher to clip the offending circuit by the fuse and again by the ECU connector and simply connect with a new wire?
Consult the wiring diagram for your answer. Without looking, I would say a bypass is not advised. You’ll want to find the issue else you might have an even worse result if you don’t.
 
Consult the wiring diagram for your answer. Without looking, I would say a bypass is not advised. You’ll want to find the issue else you might have an even worse result if you don’t.
Ugh, harness extraction. Lame! LOL. Thanks for the advice (even if it's not what I want to hear. :D)
 
Why is it so dang hard to get proper wiring info on these bikes???!!! I have a 2013 V7 schematic from Carl Allison that contradicts the 2013 V7 service manual, and neither of which match up with my actual bike with is a 2014. There seems to be zero 2014 specific info out there. This is NUTS!
 
The 5 amp fuse to the ECU is blown. Put another 5 amp in and it immediately blew, with the bike off (key not even in it). Consulted the wiring diagram and it looks like that fuse gets 12VDC from the voltage regulator. Checked that side of the fuse and sure enough there's continuity to battery +. The downstream side of the fuse goes to a pull-up resistor and to the ECU. This side of the fuse is shorted straight to chassis ground. Doh! Pulled the main ECU connector and the short to ground goes away. Soooooo, blown ECU with internal short to ground?

Are you now saying that there is a short in the harness with the ECU disconnected?
 
OK, made some progress but still no diagnosis.

Heres the fuse that keeps blowing. It's the 5 amp fuse that the service manual says powers the ECU.
IMG-5623.jpg


I took the entire main wiring harness out of the bike. Like totally out.


I then connected ONLY the ECU connector, battery + and battery -. The 5 amp fuse blew.

I then checked the connection between that 5 amp fuse that blows and pin 1 of the ECU connector where that wire terminates. There was continuity between the two, 0 ohms, and no short to either power or ground in that wire.



So are far as I can tell the connection between that fuse that keeps blowing and the ECU has no short, no break, no extra resistance. I think the harness is OK. So Again I'm leaning towards the ECU being bad.
 
Last edited:
I'm getting confused. If the fuse is blowing when the ECU is not connected, then the ECU cannot be blamed.

What's the pin number on the ECU connector your multimeter is connected to as shown in your photo? The wire colour code would be good too.
 
I'm getting confused. If the fuse is blowing when the ECU is not connected, then the ECU cannot be blamed.

What's the pin number on the ECU connector your multimeter is connected to as shown in your photo? The wire colour code would be good too.

Sorry for the confusion. The fuse only blows when the ECU plug is connected. I removed the entire harness so that I could rule out any other connector or component as the culprit. With only the ECU, Battery +, and Battery - connected on the main harness, that fuse blows.

Wire color is orange with a green stripe. Not 100% sure on the ECU pin number as the plug itself is not numbered and my 2013 service manual shows an ECU pin that's definitely different from what is actually present on my 2014.

Looking at the harness, it's this pin:

 
Yeah, it's not looking good. Perhaps you can convince a dealer to try your ECU on a similar model. This would confirm it for sure.

Have you priced the replacement?
Ha ha ha ha! What dealer? My local dealer pulled up shop and disappeared last year. I'm on my own.

Yeah, I'm like 99.9% certain it's the ECU. Maybe Todd will chime in with some sweet wisdom and convince me otherwise, but I agree, it's not looking good.

Here's the last thing I tried.

1) Verified the Orange and green wire coming off the 5 Amp fuse that keeps blowing is battery + to the ECU on Pin 9 per the wiring diagram.

2) Connected harness to power and ground

3) Measured battery voltage at pin 9 of the ECU connector

4) Verified the fuse is not blowing



So in short (no pun intended) I have battery + going to pin 9 of the ECU as it should. As soon as I plug the ECU in the fuse blows. I'm open to this not being the ECU but as you said, it's really not looking good.

Anyone got a used ECU they want to part with?
 
...and the kiss of death....

Pin 9 (12VDC in to the ECU) is shorted directly to the chassis of the ECU. It's toast. Wish I would of thought to check that before I yanked the entire harness. LOL.

Found a brand new ECU on E-Bay for $149! Woo hoo! Should be arriving about the same time I get that harness wrangled back in.

 
...and the kiss of death....
Pin 9 (12VDC in to the ECU) is shorted directly to the chassis of the ECU. It's toast. Wish I would of thought to check that before I yanked the entire harness. LOL.
Found a brand new ECU on E-Bay for $149! Woo hoo! Should be arriving about the same time I get that harness wrangled back in.
Huh. First time for everything. I’ve only had to replace one ECU to date due to (I believe) massive voltage delivery from the faulty regulators on the ‘13-15 models. So this randomly happened while riding you stated, correct? Battery terminals were tight, battery was in good operation?
I would check your standing and running voltage when you reassemble
Thanks for posting your findings! Now we’ll know what to look for.
 
Oooo! I've moved up to "pin" status! Cool!

Thanks for the feedback Todd. Agreed, I've found the failure but I've not found the cause. That's what concerns me. Will I plug in my brand new ECU only to smoke it the moment I turn the bike over? You can bet I'll be monitoring the regulator output closely.

Yeah, I was cruising along at 75 MPH, minding my own business, for about 20 miles when it suddenly barfed. The regulator has been upgraded to a new style unit that I bought from you last year after the OEM unit took out my crank sensor. So maybe the old unit cranking out 15+ volts had damaged the ECU but not destroyed it? Maybe the new unit it also outputting too high of a voltage at sustained 75 MPH running? hard to say. I'll order up a cheep-o digital volt meter and rubber band to my handlebar so I can monitor on my first few rides after I get back up and running. I'll report back once the new ECU is installed!
 
So maybe the old unit cranking out 15+ volts had damaged the ECU but not destroyed it?
It may have damaged it, but the short is an odd one. I'll ask around to my dealer friends to see if they've seen this. The one I replaced had running issues only in a specific rev range, it never caused the bike to quit completely like your short. Kudos to you for digging (deep) into it to resolve the issue.
Maybe the new unit it also outputting too high of a voltage at sustained 75 MPH running? hard to say. I'll order up a cheep-o digital volt meter and rubber band to my handlebar so I can monitor on my first few rides after I get back up and running. I'll report back once the new ECU is installed!
No on the new MOSFET VR. Highly unlikely if it is causing any issues there, but do monitor it and report back if you would.
 
It may have damaged it, but the short is an odd one. I'll ask around to my dealer friends to see if they've seen this.

Thanks Todd! Let them know that ECU Pin 9 (12VDC input) is directly shorted to the ECU housing AND to ECU Pins 7 and 23 (ECU Ground). Super interested to hear if they've seen this.
 
Back
Top