Electrical question on VFR

[keeena]

Well, I was stranded for the first time ever by a motorcycle...and it was by my Honda no less. Now I have a peculiar electrical issue and want to see if anyone here has some thoughts (VFRWorld has been no help at this point).

The bike just died randomly while I was riding in 2nd gear. Couldn't restart or bump start while coasting (which was entertaining since I was on Hurricane Mt. road). Fuel pump doesn't prime and PCIII doesn't light-up when ignition & kill switch are on.

Battery good, Engine Cutoff Relay good, Fuel Pump relay good, TOS good, Kickstand switch good, Fuses are good (all relays function properly when pulled from bike and bench-tested). I have pulled PCIII out of the loop, no difference. Used another known-good battery: no difference (both batteries have 12.8v). No hacked wiring, PCIII is the only aftermarket electrical item.

Where I'm at now is this: One power line runs directly from battery to the Engine Stop Relay.

1. Key in Off position: voltage at relay on this line is = 12.8v
2. Key in On, cutoff switch in "kill" position: voltage drops to = ~6v
3. Key in On, cutoff switch in "run" position: voltage drops to = 2.75v

This voltage is supplied/connected to the FP Relay, which is why I'm assuming the FP doesn't start. When bike is switched on, FP relay gets 12v to turn on, but then passes the 2.75v to fuel pump (guessing FP needs 12v). I wouldn't think the voltage should drop like this, but haven't been able to confirm yet. I'm assuming other bikes would be similar...so does anyone know if the voltage should drop on this type of line?

At this point my only guess is that the ECU is fucked, since its tapped into the relay circuits and seems to be one of the few things untested. I can't test the ECU w/o a special test harness.

If you want to read the long story, check out my post on VFR World.

Anyone suggestions would be helpful at this point.

[mycirus]

You said PC3 was not lit when key was on. How is it wired? What is it getting its source from? You said you are getting the 12v off the batter, does it drop when you turn something on, is your headlight bright. Just trying to make a little sense in my mind about it.

Bruce

****Edit, just read it again. The relay sounds good. Sounds like when the power is applied something after the relay is dropping the voltage which tells me something may be grounding out.

[benVFR]

1) How old is your bike? Get Honda to fix it free if possible.

2) There is an electrical system recall coming out soon for a burnout in the wiring harness.. could be that. Currently there is a hold and the dealerships are not allowed to sell VFRs without replacing the wiring harness... sounds like after that is done they may or may not be sending the rest of us recall notices. Replacing the wiring harness is a total PITA so you obviously want to get someone else to do it if there is any possibility of doing so.

3) Do you have the service manual? There is a debugging procedure for diagnosing a problem like this, and there *is* a method to run some diagnostics without plugging the special tool into the ECU. I can maybe help you out with this if you don't have it, but not from work.

4) Could be R/R as was mentioned on VFR world.

5) Remove the PC3 for a start.. obvious weak point considering it was not put on at the factory and it does connect into the wiring harness at a critical point.

[keeena]

****Edit, just read it again. The relay sounds good. Sounds like when the power is applied something after the relay is dropping the voltage which tells me something may be grounding out.

Thats what I was guessing, but wasn't certain. What confuses me is how battery voltage can go down to 6 / 2.75v? I wasn't measuring at the battery, but it might as well have been. Electrical bugs are obnoxious.

1) How old is your bike? Get Honda to fix it free if possible.
...

2002 VFR, <4k miles.

I do have factory service manual and have followed the diagnosing steps. Unfortunately, a number of causes are "open circuit" issues...which can occur anywhere in the loom.

I'll be continuing diagnosing w/o PCIII. It is kinda helpful to see if/when the PCIII lights up...I think it helps show that the ECU is also not working (maybe due to that low voltage). I'm just stuck at a point where I'm not sure what to look at next, other than ECU troubleshooting from the manual (which may help by leading to a random shorted wire?). I'd be interested in knowing what ECU tests I can do w/o the test harness.

FYI - On the day in question I had just ridden the Mt. Washington Auto Road and was on Hurricane Mountain road when it died. So very possible for something to have been shaken loose. It didn't coincide w/ hitting a bump or anything though.

[mycirus]

Thats what I was guessing, but wasn't certain. What confuses me is how battery voltage can go down to 6 / 2.75v? I wasn't measuring at the battery, but it might as well have been. Electrical bugs are obnoxious.

Yes they are obnoxious. If there is a partial ground it can cause a voltage drop. A full ground could drop it to zero ad really throw you off. I would check the wiring, especially if there is a recall. Sounds like it could have melted somewhere. This is going to take you hours to find and no time to fix. Make sure nothing is pinched under the tank or anything.

Bruce

[keeena]

[benVFR]

Honda's electrical connectors on this bike are nearly nuclear proof and everything has moisture covers...

I bet it's more likely something is burned out rather then disconnected.

But the ECU would be easy to reseat... just take the right cowl off and it's right there.

[keeena]

Fixed the problem for the moment. The Fuse-B plastic was warped, but not blown. The plug 3" downstream was fused together and needed vice-grips to disconnect. It originally tested OK for continuity & voltage at rest. I ended up bypassing the torched stuff and bike started right up.

I guess this toasted Fuse-B is kinda common. Now trying to understand why this happens on stock bikes and how to fix it. Off to waste some time reading...

Thanks for the help guys.

[Royb]

Check this out

Safety Recall - VFRD

and this

Producing A Fix For The Blue Connector Ground - VFRD

and this

How To: Replace 30amp Fuse Wires - VFRD

Do a search here for tons of threads dealing with elerctrical problems on 1998 - 2006 VFRs (mostly under 6th generation)

VFRD (Powered by Invision Power Board)

Good luck!

[benVFR]

It's a design defect Keeena..

Honda's been a dick about admitting it AFAICT.

What I don't get is how I got lucky enough to dodge a bullet.

I put 10k on my first VFR and 17k on my second so far and have not had mine melt/burn yet.

[keeena]

It's a design defect Keeena.. Honda's been a dick about admitting it AFAICT.

Haha. Looks like Honda is now recalling the entire wiring harness on '02-05...just got the letter a few days ago. Hopefully it helps. I wonder if they'd say exactly what was wrong w/ the original.