I have searched around and see that there seems to be a fair amount of problems with the oil pressure gauge on my style of truck but nothing that sounds similar to my problem. Sometimes when I turn my key to the ON position (not running) the oil presuure gauge will go up to the top of the NORMAL range then when I start the truck it will drop to zero for a little then come up to the top of the operating range again and stay put. I will drive for a while and it will drop to zero for a few minutes than come back up. I though at first it was a bad connection on the sending unit so I checked that and cleaned it, still acts up. Any ideas?

 

When my sending unit went bad, it just stayed in one place. I'm not sure how to check it, but it might be a good idea to check and be sure your oil pump is not going out.

 

What leads me to beleive that it is an electical or sending unit issue is when I turn the key to ON the gauge will stay at the top of the operation range and stay there untill I start the truck.

 

OK I took out the dash cluster to make sure there couldnt be a bad connection there. Double checked the connection on the sending unit and put some dielectric grease on it. Just like before, half the time if I turn the key to the ON position (engine not running) the gauge will go to the top of the operating range and stay there even after I start the engine and will not move at all. The other half of the time the gauge will not budge when I turn the key and will stay at zero after I start the engine. I although I have not put an oil pressure gauge on it Im sure this is some kind of an elecrical issue. Why would it show pressure without the engine running?

 

I'm pretty sure there is a PCM reflash for this problem. I don't know about the going to high, but the momentary drop to 0.