:-c: :-c: My low pressure light illuminated during my commute... Oil level is okay, sight glass does not change on starting bike. I know that the main seal does need replaced but is not critical just yet ( that will change probably soon). My question is will the seal have an effect on the oil pressure?

The rear seal will have no effect at all on the oil pressure however the fact that it came on to me means there is a problem that needs attention. BMW will say that the light coming on at idle with a hot engine is nothing to be concerned about but if you are spending a lot of the commute at idle and hot in traffic then there is a potential problem of bearing damage due to excessive wear.
Did the light come on only for a moment or did it stay on and when you said stayed the same do you mean while the engine was running and if that is so don't run it till you find the problem which would very likely be the pump itself.

might be worth pulling the oil filter and confirming that it is sealed properly to the base .....im thinking if it was loose could be a reason why pressure is low ...as its a full pass through filter system .

also check that the cabling to the oil pressure switch is good and has no corrosion ...or badly crimped cables to connector ...which could be giving a false indication to the system

just some thoughts  as it appears that not many of us have seen similar issues ....other than getting the wrong connections to the water temp sensor and the oil pressure switch ...right at the same location under the pump and easily confused ....
tip put some coloured heatshrink around one of the wires to identify it ....and write it down somewhere on the bike (tool lid ?)

good luck

charlie99 wrote:....
also check that the cabling to the oil pressure switch is good and has no corrosion ...or badly crimped cables to connector ...which could be giving a false indication to the system
.....

Good idea and worth checking first. Just remove the wire from the sensor and if the light still illuminates when you turn the ignition on then you have a short.

The bike is new to me (my first bike ) what a fantastic bike!! Anyhow in need of an  oil change, so I drained it over night. Looked like around 5 pints! Oil looked newer, I guess it had been sitting for a few years.

I'll change out the filter/oil and diagnose the wiring as suggested. Fingers and toes crossed the light will go out 

You can test the oil pressure circuit by pulling the wire off of the oil sensor and grounding it. That should make the oil warning light come on. (That's what the sensor does when oil pressure is low.)

Have you washed or ridden the bike in rain lately?  Is the oil light an LED?

Shortly after I got my K75 I nearly soiled myself when the oil light came on in the first rain storm I rode in.  Water getting under the cap combined with dirt/salt created a leakage path to ground to light up the oil light.

A good cleaning and a smear of dielectric grease did the trick.

I would also check the wire where it travels through the ignition sensor cover for worn insulation.

duck wrote:You can test the oil pressure circuit by pulling the wire off of the oil sensor and grounding it. That should make the oil warning light come on. (That's what the sensor does when oil pressure is low.)

Thanks for the suggestions, an update... I changed oil filter and new cover seals, cleaned and recrimped a loose terminal and the warning light turned off for a time. HOWEVER the light is back on 

I checked the circuit this morning with the wire off the sensor (light went out) however when grounded on the pump cover the light did not come on. Puzzled I reconnected it to the sensor and the light remained off. It remained off for 10 miles on my way to work but lit up again. I will add there is an oil weep at 6 o'clock on the pump cover and a small small drip at the pressure sensor plug. Is low oil pressure the obvious answer? short circuit? faulty sensor? The oil sight glass empties immediately when I start the bike if it's any clue.

Any input is very much appreciated! Thanks Gents...

Don't waste anymore of your time.  Pop for a new oil pressure sender.

http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51743&rnd=04282014

Look under water/oil pump in the engine section.  20 Bucks plus shipping.  Use the discount code "NovemberVIP" at checkout and get 3 bucks knocked off.  If you need anything else get it now.  The more you buy, the more you will save with the November 15% discount.

You might have a leaky seal, but I seriously doubt it will leak enough to drop the pressure to trigger the idiot light.