Motorcycle Forum banner

Can Low Oil Sensor Block Ignition?

6.1K views 10 replies 8 participants last post by  stexch  
#1 ·
'98 Yamaha Virago XV1100K has two issues:

1. It always starts right off when cold. If you shut it off and try to restart without waiting 2 hours, it will click once each time you hit the switch, but won't restart until at least two hours have passed.

2. The low oil level light comes on and goes back off at random times, even though I know it's full of oil.

My question is whether or not it is the low level indicator that is preventing ignition. If this is the case, is the indicator sensor itself the only part that needs checked, or is there a relay somewhere as well?
 
#2 ·
The clicking noise is likely a low/weak battery or a bad connection.

I would double-check to see if that light is a "low level" or "low oil pressure" light. The low oil pressure light is much more common. I can't say that I've ever seen a low oil level light on a motorcycle, although it's not impossible I guess. It can be signalling that the engine is not being properly lubricated which could lead to expensive problems in short order.
 
#3 ·
Per owner's manual p. 5-2, it is an oil level indicator light.

My question is whether there is an ignition defeat tied to the level indicator. If so, it may be impractical to repair (if we have to separate the cases), in which case we may bypass the circuit.
 
#4 ·
Regarding your suggestion about it being a bad battery or a bad connection, one would think that this would cause a consistent failure, rather than only be on warm restarts. My mechanic is somewhat handicapped in that this is 9.6V and all his test equipment is for 12V.
 
#5 ·
Some engines do have a low-oil shutdown, and the sensor switch can get crudded up and malfunction. To check it you'll need to know if it's a normally open (NO) or normally closed (NC) switch, but NC are more common from what I have seen. Usually a NC switch will open when the oil level gets low allowing current to pass through the warning light, (thus lighting it,) and also allow the current that would normally run through the ignition system to bypass it and ground to the engine case, thus shutting off the ignition. Once you know which type of switch you have just measure for current to the switch when the bike won't start and you'll know if the switch is working when it should.

As an alternative you can remove the switch from the case, clean it off real good, and stick it back in and see if that works. :) In addition, there's probably a way to bench test the switch, but you'll have to find out specifics for your particular bike.
 
#6 ·
know it all response to indicator shutdown syndrome...

motorcycles have all kinds of shutdown devices on them. The oil indicator is usually not one of them. The sensor itself may be defecting.
Call the secret service and see if they have a defecting oil sensor...

FOOD FOR THOUGHT? If there is a problem, it can usually be traced to other problems. And if the problem is not effecting other things, it is usually somewhere in the same circuit as the problem you are experiencing.

I would 1. pull the oil sensor, give it a good bath, and try it again. 2. check all the wiring loom connectors for wires that are frayed at the connector. fix anything you find. Sounds like you have a wire that is frayed out and only has a few strands connected. The resistance needed to operate is good when the wire is cold, so look in areas that get hot. 3. shoot any gremlins or gnomes in there.
 
#7 · (Edited)
For some crazy reason Yamaha uses oil level sensors instead of oil pressure.
The sensor has no effect on the Ign or starting system and is only connected to the idiot light.
With age the sensor becomes less responsive making the light come on when the oil level is OK.

Hard starting when warm? I guess an electrical connection could be heating up and failing under load.
 
#10 ·
Time to go back to your battery connections. Do not just look at them and wiggle or tighten them. Instead remove each connection and clean the electrodes, then reattach and snug the connection. Warning over tightening is very easy with typical lead posts. You may find that the connecting cable feels way too easy to bend which would mean internal damage to the cable.
I ride a Victory and they are notorious for loose connections that look good to the naked eye. A loose or degraded connection can give all kinds of strange symptoms.