Oil & Temp lite come on above 3,000 rpm under load. 1988 200hp.

[Fishermanx44]

I hope some one has run into this before. I went to my local Yamaha dealer, & he suggested a new computer, & my experience is a computer never fix's it. a little info, this is the port engine of a pair. I have swapped oil pumps, tanks, senders, & hoses from engine to engine. with no change. I also thought it might be a minor over heat condition ( I can't find owners manual on line) checked pop off valve, removed thermostats & put new water pump in. inside of block is clean. when lights come on I can stop and put both hands on thermostat housing's I haven't put a infrared thermometer to it yet, but my guess is 140-150. I have also tried triggering lights. by opening & grounding temp sensors & oil level sensor. only the red light illuminates and alarm horn sounds

[boscoe99]

Oil and temp light on at the same time indicates a low voltage situation.

[Fishermanx44]

Thank you for your response

I am assuming your pointing to a ground or corroded connection. I have visually checked the wiring & ground connections, some with ohms meter. can you point me to the circuit in question. I have no wiring diagram. If you knew where I could find such information I would be extremely grateful.