Headlight inop (ecu?)

[sleepymas]

My headlight stopped working the other night on a ride home. i have checked circuts and found that i can jump the relay and they work just like they should. so i found that the relay is not being commanded on by the ecu. i can ground the control circut of the ecu and the lights come on like normal. does anyone know or know where i can get a decent circut description for the lights. i need to know if the ecu automatically turns them on with key on, or if the ecu needs an input to turn light on. really dont want to blow money on an ecu just for a headlight... i will probably just make a jumper switch to ground that wire instead, but before i ghetto rig it i want to be sure that the ecu is the problem.

 

[ChevyFazer]

Odd to say the least... Are you sure it's. Or the relay since you can jump it out and they work? If the ecu had something to do with it I would think that all of your running lamps would be out as well, since all the ecu does for the lights is say yup the bikes runnin, fire up the lights

 

[sleepymas]

You are right all it does is say yeah lights are on, but it does this by grounding the yellow and black wire. this wire runs up to the control side of the relay and completes the circut so the contacts will be shut and power can flow through the large wires to the lights. I jump the yellow and black wire to ground everything works fine. so i know the issue is on the output side of the computer, it is not that strange to have output circut of a computer fail, just want to make sure i am not missing anything on input side. if it helps any i am a master auto tech, and in our manuals they give circut description and tells what the inputs are, but i notice in the motorcycle manual it does not. To add insult to injury they do not even show ecm as a possible reason for lights to fail. i have tested all switches relays and continuity of all wires, and have come down to a simple jump of control circut wire to ground will fix. my solution will be to just add my own control wire that grounds when key is turned on, cause i have no plans to shell out the money for a computer.

edit: relay is installed, i am jumping the wire down by the ecm, i just shaved some insulation off the wire and jump it to ground, the rest of the circut is fully intact.

 

[Motogiro]

Correct the relay does not activate until the engine is started. The relay remains keyed after the engine is started and even stays on after you hit the kill switch as long as the key is still on. I will get you a schematic.... The ECU controls ground path of the headlamp relay.

 

[Motogiro]

There may be other conditions logically that must be met for the ECU to go low for the relay but as you've said there's no data.
Additionally: Do not force a low on that wire while it is still hooked to the ECU. You could short a junction in the ECU while that output is held high by the ECU.

 

[Motogiro]

Odd to say the least... Are you sure it's. Or the relay since you can jump it out and they work? If the ecu had something to do with it I would think that all of your running lamps would be out as well, since all the ecu does for the lights is say yup the bikes runnin, fire up the lights

The headlamp relay is separate from the running lights. The engine must run for the ECU to activate the headlamps. When you turn the key on the headlamps are off but the running lights are on.

On my SV all lights come on the key and during starter operation the headlamps only are turned off by an unloader relay. I do like the power management for the FZ6.

Now how does the ECU know the engine is running? RPM? Stator/ regulator/rectifier output?

 

[ChevyFazer]

The headlamp relay is separate from the running lights. The engine must run for the ECU to activate the headlamps. When you turn the key on the headlamps are off but the running lights are on.


Now how does the ECU know the engine is running? RPM? Stator/ regulator/rectifier output?

That's good to know, when I first got my bike all the lights on the front end were spliced into the head light circuit, and when I say spliced I mean striped back spun together and taped up....so I dug into it trying to do it the "right" way i put it back, to the best I could remember, how my Suzuki was. So nothing comes on until my bike is running, and everything stays on until I turn the key off. That schematic could have come in handy at the time lol. I don't plan on going back into it though, I put "western union" splices on everything solider it up and heat shrinked it. It works fine and I live by the if it ain't broke don't fix it moto lol