oil pressure question

[oldfatman7]

Hello,
I have a question for anyone who might be able to help.
I have a 94 e320 that I am having problems with the wireing harness.
My local shop had to replace a/c parts under the dash and since I am having issues.
They have had to tape some wires and I know about the bad wireing.
I am going to have to replace the harness soon.
The problem I am having now is my wife is 200 miles away and just called and said the oil pressure dropped to 0 .
I changed the oil last week and she got out and checked the level and it is fine and the engine is running smooth..
The question is do you think this could be a wireing issue or is there a chance the oil pump went out.
Any help would be great.
Thanks Dan