ECM failure

Hello everyone!

I am new here and wanted to share your thoughts on an ECM failure. I just started the resurrection of an abused 2006 VFR800 CA model. I got it with a no-start issue which was because there was no power to the coils. It turns out the previous owner removed the 30-amp fuse from the starting circuit and disconnected the main harness... for good reason...

I repaired the starting circuit and ran continuity checks to verify everything was wired correctly. as soon as I plugged in the ECM and powered on the bike and tried cranking the engine, I got all the blue smoke. It melted the black/white wire from the ECM all the way to the end of the harness. It was obviously a dead short. I traced the fault back to the ECM where a ground pin was shorted to the black/white wire. The bike came with a "spare" harness but the black/white wire was melted on it too, so it has happened before on this bike. My initial is that the ECM is toast, but I wanted to make sure I wasn't missing something before I start throwing new parts at it.

 

lets get chief inspector GRUM, elecktrikal expert #1, in on this case.

 

Haha you're a funny fella Squirrelman, I keep tellin ya. I'm no expert.

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If those shorts Only appear on the ECM itself and Not on the wiring harness then no doubt the ECM is shorted. As to why the Black/White wire melted instead of blowing Main Fuse B 30amp is a mystery! I know of ECMs shorting like this due to overvoltage from a faulty R/R, output of over 17v and that situation definitely takes out Main Fuse B.

 

keeping running enough honda bikes over enough years tends to make one either a minor electrical expert or a miserable pedestrian.

 

I did some more investigating and the red connector on the starter relay was cooking too. The connector for the main 30-amp fuse on the R/Y to R/W was missing so I made my own. Could my homemade connector have caused all this, or do you think it was the power-to-ground short in the ECM? Either way, I'm needing an ECM and probably a harness too. The bike has never run since I started playing with it, I was first just trying to get 12V at the coil so I didn't check the R/R yet. However, it looks like the bike has battle scars from previous R/R issues.

 

Might be worth confirming you have a 30amp Fuse fitted for Main Fuse B. No possible way your fuse wiring replacement has anything to do with the issue unless of course you had a greater than 30amp fuse fitted.

The Starter Relay fuse is Main Fuse A = Supplies all other services except EFI
Main Fuse B = All the EFI stuff. along with short circuit protection for the R/R.

Have you confirmed the ECM is a dead short to Ground or a partial short? I'm sure if it was a dead short it would have taken out Main Fuse B before frying your wiring! A partial short might take the current level close to the 30amp fuse without blowing however this could allow the wire to become excessively hot as in your situation. What is the state of the main ECM Green Ground wire?

The Red 4P connector having the Red Wire for Main Fuse A is a common failure point, high resistance joint can occur from poor contact, or moisture, or extra load by added accessories etc. The white frosty stuff around your red 4P connector looks like moisture ingress. You can greatly improve this with better tinned type spade connectors, some OxGard applied to the terminal AND taking advantage of the spare unused connector for the Fuse and splicing that into the Red wire. See attached with added Red wire splice.

 

I should go and test that the ECM is a dead short with the harness attached. I just checked continuity across all the ECM pins since I couldn't think of another way to short-out the B/W wire right after I traced all of the B/W wires and the green ground wires. It is definitely a 30-amp fuse, and the main green ECM wire looks perfect. I traced the green ECM wire all the way back to the grounding block and there was no damage there. I split open the harness to inspect it all and the damage was limited to the B/W ECM wire.

There is one other thing I noticed... A previous owner messed with the B/W and Green wires on the Diagnostic Link Connector with exposed solder joints (now covered in the pic) they could have touched. They don't look like they did but just thinking what else would have caused this fault. I inherited another harness with this bike and it had the exact same issue. I wish I would have checked first before powering it up...

I understand splitting the load across two terminals. I will do that if I repair this harness or on the next one.

On the bright side, I now have time to finish repairing and repainting the dented and bashed tank (which was nice until I dropped it, and it took a tumble across my driveway...) Those cheap dent puller kits on Amazon actually work!

 

I am back on this project again after taking a break for a while. I am still having a no spark issue at the plug. Since last time, I have replaced the wire harness, ECM, IPG, and Cam Sensor. I also checked to make sure I get a ground at the ECM with the side-stand switch and the clutch switch up and pulled in, which I do. I get 12V at the coil and have good grounds to the coils. The bank angle sensor and engine stop relay both function correctly too and all fuses are good. Is there some other ECM logic that prevents the coil from firing? The bike cranks fine and has a really good battery. I do not have any of the fuel system components connected, I wanted to make sure I had spark first. I am assuming the coils are good at this point. I haven't got any spark at any coil so far. I could be missing something obvious, so feel free to point it out!

 

I also have an ECM code 19 so that would be an IPG issue. I guess that's where I need to focus now.

 

I have replaced the IPG and still no spark. I used an oscilloscope to make sure I was getting a signal out of the IPG while cranking and I get a distinct signal so as far as I can tell it is working. All of the clutch, side stand, and fuel cut relays work just fine. I am now wondering if the coils are faulty unless I am doing something wrong by checking for spark the old-fashioned way with the coil and plug outside of the bike. Any other ideas would be appriciated!

 

Fixed!! After all this time it was just a loose W/Y wire in the black connector to the ECM. It was pushing away just a little every time I plugged it in. That is why when I back-probed it, I was getting a signal. It was my first time hearing it run since I picked it up, it's an awesome sound. Now I just need to finish everything else.

 

Good find, DTC 19 wasn't lying, it's a fatal error, equals dead engine.
The W/Y wire pushed back problem is possibly caused by a damaged pin locater, were you able to confirm this and rectify?

ASAP confirm your charging voltage is good as there's a high probability excessive voltage shorted your original ECM.

Well done and good luck with the bike.

 

It is definitely a damaged pin locator. That is my next fix for sure. I changed over to a mosfet reg/rec and pulled it out of the harness so that the ECM and harness can never see more than battery voltage now. There was evidence of overcharging in the past so that was probably the cause of the original fried/shorted ECM.

 

Well done!

Thank you for sharing the findings.
I hope to never run into that problem. Glad you have it sorted.

Now you can post some photos of your finished project in the wild.

 

It's alive and I get a steady 14.2V so the charging system is solid.

 

Excellent, good job.