V7C sudden oil pressure light failure

[icenian]

The oil pressure warning light on my V7C has failed suddenly, not coming on (even when it should, when the engine is not running).

It was fine until it went into the workshop for the routine 12 month service. On leaving, it flickered a little when the ignition was on before starting up (i.e. should have been on). I didn't think too much of it, as it has been a wee bit temperamental when wet before. Next day, it won't light up at all (apart from when I first turn the ignition on, when all the dash lights come on and the needles do that sweeping thing).

I'd be grateful if anyone could help me with 3 questions...


1 - Am I right in thinking the switch closes the circuit, so if there's a dirty connection or a break in the wire, the light won't come on?

2 - It's an oil pressure switch, so provided there's enough oil in the bike it should be fine to ride?
(I suppose in theory the oil level could be OK, but an oil pump failure could lead to low pressure, but that seems unlikely on a <3000 mile bike...)

3 - The oil level looks a bit high to me. There's no way that could affect the switch is there, when the engine isn't running?

Thanks!

tim

[john zibell]

Switch is normally closed to provide a ground path for the indicator. Now if it never comes on, it has probably stuck in the open position. Remove the wire from the sensor and contact a ground with it. Turn on the ignition and the oil pressure light should come on. If it doesn't, wiring, if it does replace the sensor. The oil pressure sensors are a high failure rate item and always have been.

[nutman]

Check that you have power to the bulb. The wire to the sensor is almost impossible to get to. You can put a test lead on a long screwdriver and reach into the valley and ground out the switch that way, but don't pull off the wire. Good luck

[icenian]

Thanks for the replies. Shorting the switch against the frame turns the light on, so the fault seems to be the switch.

I wonder why it failed at the service? It wouldn't have been touched. It usually takes a few seconds for the oil pressure to build up after the sump has been drained; I can't think why that would break the switch, but it's the only thing I can think of that could be connected to an oil change. Unless it's just coincidence.

[icenian]

Delayed follow up on this, as I didn't get to ride for about 2 weeks.

After riding the bike for another 20-30 miles, incl. starting up twice, the oil light started to flicker back into life. Another ~100 miles and a couple of start ups, and it seems to be back to working normally.

It was just messing with me, then...

[mudwasp]

We have A V7C and a V11 Scura, they both seem to like to play jokes on us-you gotta love a bike with a sense of humor that can heal itself

[cgalardi]

I went through three of these oil pressure sensors on my 2006 Breva 1100 and a few on my 1991 Alfa Romeo 164L and my 1986 Alfa Romeo Spider. Maybe an Italian thing!

[icenian]

wouldn't mind if it was easy to get at

it's a bit weird when to get access to the oil pressure switch, step 1 is remove the horn...

[cgalardi]

On my Breva 1100 it was located under the alternator. Is it similar on the V7C?

http://cwpg.blogspot.com/2009/06/replac ... ssure.html

[icenian]

On my Breva 1100 it was located under the alternator. Is it similar on the V7C?

I can't quite make it out from those pictures, but it looks as if it is between the cylinders? If so, it's a similar position.

There's a clear picture in the service manual, though it's in the engine removal/installation section (there's no picture in the section about the switch itself). Easy to find by searching the PDF for "oil pressure switch".