First time she died in 13 years...

[gyrfalcon]

Well something interesting was found today...

Last night I wrote an inquiry on Grok AI....

i have a 1989 Fj1200, i was on a trip and noticed my tachometer was at zero. then i started getting rough engine performance and the bike died 5 minutes later. I have 12.8 volts at the battery, i have voltage at all 4 fuses, i have voltage on both sides of the ignition connector, I have voltage on both wires going to the alternator with the key on, the fuel pump runs when i turn the key on and the starter will start the engine normally, The headlight and high beaam are working the instrument lights and front marker lights are working what is not working is the nuetral light the tachometer the front signal lights the horn the clock the rear tail lights the rear brake light the rear signals.. what is causing this electrical trouble
Most likely cause: A blown or faulty "Signals" or accessory/ignition fuse (or a break in the shared power feed wire, often brown), combined with a possible poor ground or connection issue downstream.⁠Fjowners
Your symptoms show a split in the electrical system:

    Working circuits (headlight/high beam, instrument lights, front markers, fuel pump on key-on, starter, voltage at battery/fuses/ignition switch/alternator wires) → Main power, headlight circuit, and starting/ignition power are intact.⁠Justanswer
    Non-working circuits (tach, neutral light, front signals, horn, clock, rear tail/brake lights, rear signals) → These typically share a common fused power feed (often called the "Signals" fuse or similar accessory circuit on FJ1200s) and a brown power wire that branches to the dash/instruments and rear lighting.⁠Vmaxforum

The rough running and sudden death suggest the issue may have started with an intermittent connection or overload that affected ignition/tach signal temporarily (tach gets a pulse from one of the coils). Once power was lost to key accessories, the bike became unrideable.⁠Fjowners
Quick Checks (in order)

    Double-check all fuses, especially the smaller ones in the fuse box (often under the seat or near the battery/cockpit). Look for a "Signals", "Accessory", "Ignition", or similar 10-15A fuse. Even if you see voltage at the fuses, pull and visually inspect/replace them — corrosion or internal failure is common.⁠Fjowners
    Test for power at the affected components:
        Use a multimeter or test light on the brown power wire at the instrument cluster or rear light harness (key on).
        No power there but good at the fuse = broken/chafed brown wire somewhere in the loom (very common on these bikes, especially where it exits the dash or runs under the tank/seat).⁠Vmaxforum
        Check continuity on that wire.
    Grounds — Clean and tighten all major ground points (battery negative, engine/frame grounds, rear light grounds). Poor grounds can cause exactly this kind of partial failure.⁠Fjrowners
    Ignition switch connector — These often overheat/melt/corode on FJ models, causing intermittent or partial power loss. Wiggle it and inspect for heat damage.⁠Fjowners
    Tach-specific — Grey wire from the #2/3 coil for the signal. But since other dash items are out, it's probably the shared power feed.⁠Fjowners

Other Possibilities

    Wiring harness damage (chafing/rubbing, especially on a trip with vibration) — Common culprit for sudden issues.
    Flasher/turn signal relay failure affecting related circuits.
    Less likely: Bad rectifier/regulator or stator (but you have battery voltage and lights working).

Start with fuses + brown wire continuity + grounds. These bikes are known for harness issues and corroded connections after 35+ years. A Haynes or factory service manual with the wiring diagram will help pinpoint the exact fuse and wire colors.⁠Fjowners
If you find the bad fuse or wire, fix the root cause (e.g., repair chafing) to prevent recurrence. Let me know what you find on the voltage tests at the dash/rear lights!


Starting with the first QUICK CHECK.. I pulled the fuses and the very first one I pulled, the 15amp beside the 30 amp was blown.  I had checked all four of them for continuity with the MM (in the box) and they were good. After putting a new spare in all the missing electrics started working. I have not checked the tach yet because the tank is still off but it got a new RPM petcock and filter anyway. I guess the reason for blowing the fuse remains unknown but I will probably put it back together with some silicone tape on the 2 connectors for now and see if the alternator is back or not. Probably a good idea to not stray too far from the garage and see if I blow that 15 amp again..  and make sure I am carrying a spare.

No idea how long those fuses last or have been in the bike but I know I've never changed one before today.

I guess I will know soon enough if that fuse blows again and or if the tach is working or not..

Thanks