No oil pressure and 7 codes

So i have a 1999 2dr 5speed w/ a re 5.5" lift and 33s. I recently took my interior apart to install a sound system, Ceiling mounted amp and real nice stuff. but that has no been completed. in the time have have been driving the car around while its apart i have been getting a grinding nasty sandy noise coming from i think my ac compressor or maybe another pulley. So thats been for about a week or two. last night only made it a few blocks and notices the check gauges light came on and had little or no oil pressure. i drove home and pluged it into a comp and got these 7 codes

Oh! one more thing....for some time know i have had a known problem and 2 codes.....i pulled down the t case without disconnecting a wire and caused a short i couldn't find. i had no speed showing in the car and it would shut off when i went to N and stopped sometimes. the codes i believe from that were p0500 and p0138 the rest is new

p0141 Category Powertrain
Definition O2 Sensor Heater Circuit Bank 1 Sensor 2

p1388 Jeep: Auto shutdown relay control circuit

p1282 Jeep: Fuel Pump Relay control circuit

p0500Category Powertrain
Definition Vehicle Speed Sensor "A"

p0138 Category Powertrain
Definition O2 Sensor Circuit High Voltage Bank 1 Sensor 2

p0351Category Powertrain
Definition Ignition Coil "A" Primary/Secondary Circuit

p0320Category Powertrain
Definition Ignition/Distributor Engine Speed Input Circuit

this forum has always helped me out and this time i dont know where to start so i really need the help? thanks

anybody?

Your main concern should be the CHECK GAUGES / OIL PRESSURE fault you saw as it could be the most critical to the life of your engine.

What is the oil pressure reading now? Both at idle and on the highway?

Spec is as follows:

*Not less than 13 psi at hot idle
*Between 37-75 psi over 1600 rpms

If there is ANY question, you should get a hold of a "mechanical" oil pressure gauge and temporarily install it where the oil pressure sending unit resides. Compare your readings to what you see on the dash gauge. Then you'll know if you have a real problem or not. A mechanical gauge can be rented for a few bucks at many parts stores. I'd highly recommend this.

well i cant find an oil presure gauge for rent and the cheapest is $45 (long island) anything else i can do till then?

so lets say i have low oil pressure. the check gauge light comes on before the truck gets warmed up and it seems it cant keep any pressure. i dont know what to look at oil pump? on top of that the codes i got make everything seem worse although the truck runs. should i look at the oil pump?

Got Harbor Freight?

http://www.harborfreight.com/catalogsearch/result?category=&q=oil+pressure+tester

so today i changed the oil pressure switch and that was it. i was told that the way the engine is in the 4.0 i would have heard a lot of noise if i wasn't getting oil.