FJ1100 ignition fuse keeps blowing

[SausageNips]

I have an 85 FJ1100 won't start anymore.  I pulled it out of the garage this morning and fired it up.  It idled for about 3 minutes, then shut off.  The neutral light illuminates, and when i try to start it, the oil light comes on.

- the oil level is good
- i checked the cut-off switch to make sure that was opening and closing correctly
- the battery is fully charged and showing about 13.3V

I was looking in the Haynes manual to find the starting circuit cut-off relay, but the only relay I ofund by the front fairings was one for the signalling on the left hand side.  I checked the 3 fuses and the 15 A ignition fuse was blown.  I replaced it and it immediately blew again.

At this point, I'm not sure where to go from here.  A previous owner added the Dynatek Dyna 2000 digital ignition module, so I'm not sure how much that changes things in the troubleshooting process.

Any advice would be greatly appreciated - thank you!

[FJmonkey]

A blown fuse indicates that somewhere in the circuit too much current is passing through. A dead short is very common. Do you have a multi meter or test light for testing shorts in a circuit? If not, get one, or your discovery efforts will be like chasing smoke. If not then at least find the wires and physically trace their paths to see if can find any visible damage.

[SausageNips]

I have a fluke 87, but I haven't been able to spot any obvious physical damage to the wires.  Where would you recommend that I trace back from, the fuse block?

[FJmonkey]

I have a fluke 87, but I haven't been able to spot any obvious physical damage to the wires.  Where would you recommend that I trace back from, the fuse block?

See if the wires to/from the fuse box (of the blow fuse) have continuity to a frame ground. If you have a dead short then you start at one end and test along the way till you get to the other end.

[Pat Conlon]

I assume you checked that your run/stop switch is in the "run" position

The key in your description is: "when I try to start it, the oil light comes on".

You have a Owner's Handbook, correct? If not see my signature line and down load one for free.
In the Owner's Handbook, it describes a procedure where you can check the oil level light.
You turn the key on, click the handlebar run/stop switch to the off position, then press the starter button.
The oil level light should illuminate. Of course the bike won't start, but the oil level light should illuminate and in your case it does..

Based on this, I would check your run/stop switch and circuit first. The power to your ignition box is fed by this circuit. If this circuit (or the switch itself) has problems, your bike will not run.

Lastly, in the Owners Handbook is a color coded single line wiring schematic for your specific model FJ.
You really need this schematic to help you trace down pesky electrical problems.

Hope this helps.  Pat

[fj1289]

Under what conditions does the ignition fuse blow immediately?  Key off or on?  Kill switch off or on? 

It definitely sounds like a short. 

Take a good look at the wires in the wiring harness - look for signs of over heating. 

Here is the PDF of the install instructions:  http://www.dynaonline.com/skins/downloads/instruct/ddk7-1.pdf

Page 2 has the wiring instructions for a "stock" install.  Double check the PO's work.  You may have a wire chaffed through and grounding out on the frame or tank. 

Page 5 has some troubleshooting instructions. 

If, for example the fuse blows when the key is on and then you turn the kill switch on - you can see if the lights on the module flicker for a moment to see if it's getting power or if the problem is before there possibly.  You can also try holding onto the wires for the system and see if any get hot when the fuse blows - that would be the problem child.  You can also try unplugging the module and see if the fuse still blows.  You just have to try to think through the issue to find clues where to look for the problem to help narrow it down from the entire harness....

[fj johnnie]

 Another member of this forum who I imagine will weigh in soon had this problem as well. Apparently the signal lights run on the same circuit , and one of his signal wires had chafed the insulation and shorted to the frame.

[Zwartie]

I have no idea what you're talking about!

Oh, wait...http://www.fjowners.com/index.php?topic=2662.msg21063#msg21063

Zwartie

Another member of this forum who I imagine will weigh in soon had this problem as well. Apparently the signal lights run on the same circuit , and one of his signal wires had chafed the insulation and shorted to the frame.

[SausageNips]

It looks like I found it - It appears the Dyna 2000 had an internal short.  I spoke with their tech support and they want me to mail it off for evaluation and replacement.  They were incredibly friendly and helpful and, worst case scenario, I'm out $150 for a new unit (they will sell it to me at cost).

Thanks again to everyone for the helpful advice!