Oil Pressure Gauge Failure

[mb21v05]

I have a 2005 Launch 21V and my oil pressure gauge is not working. When the boat is off the needle on the gauge rests at zero. When I crank the engine the needle drops down into the negative. The needle does not fluctuate when I engage the throttle. My engine is not showing any indications that the oil pump failed (no knocking, chattering, or whining). After running the engine I pulled the dipstick and opened the cap on the oil reservoir and both indicate the oil is circulating. All wires to the gauge are secure.

Unfortunately I am more than three hours from my nearest Supra dealer; therefore, I want to try fixing this one on my own.

Any recommendations?

[lively]

take wire off oil pressure sending unit .. ground to block with key on .. if the needle pegs out then you have a bad sender , if it does not , then the gauge is bad

[mb21v05]

take wire off oil pressure sending unit .. ground to block with key on .. if the needle pegs out then you have a bad sender , if it does not , then the gauge is bad

Thanks for the response! I am having trouble locating the sending unit to disconnect the cable. I thought it would be in the proximity of my oil filter. Can you give me any pointers???