I have a Keda 17 multimeter. It is a basic auto ranging multimeter. When set on ohms, it reads 363.0 ohms for open circuit and all resistors read much less than their marked value (10k reads 321 and 10 ohm reads 2.8

Can anyone help me fix it?

 

I can not find any information on the internet about that meter. Does it have banana sockets for the input leads? Does it have a separate input for ohms or does it use the same input as for DC volts?
On Ohms function, multimeters supply a constant current to the positive input terminal and the meter measures the DC voltage across the resistor being tested. From your description of the problem, it would appear that something is partially shorting the input terminals. There may be an over-voltage protection circuit across them which has failed.
That's about all I can suggest without knowing more about that particular meter.
Regards,
Keith.

 

Thanks Keith. Here is more information:

 

Without a circuit diagram, I can only make guesses. Start by measuring the resistance between com and volts input terminals when the meter is in a DC volts range. The resistance should be really high. If it is not, check the resistance of the green thing just above F2. It looks like some kind of surge protector. If it measures the same resistance as across the terminals, I would suspect it.
Check all the diodes you can see. One may have low reverse resistance. That is about all I can suggest for now. Good luck.
Keith

 

Many multimeters have a battery that they use to measure resistance. If the battery is near dead you can expect this behavior.