My 91 xj is reading a total of 7 (3 valid?) codes. I want to know if someone could help me figure out what to replace first or where to start looking... Please help, my mileage has halved since this started.
To start out with, the check engine light is on full time, its running rich and has noticeably less power. The codes are displayed exactly as follows:
12 - Battery or computer recently disconnected-N/A
35 - Cooling fan relay circuit open or shorted
OR
35 - Idle switch motor fault - check connections
33 - Air conditioning clutch relay circuit open or shorted (NO A/C)
13 - MAP sensor or vacuum line may not be working
13 - MAP sensor or vacuum line may not be working
52 - Oxygen sensor stuck at rich position
55 - End of codes-N/A

I appreciate it a ton, thank you!
-Brian

 

Try this...

 

You could have water in your fuse block maybe? or a moist ecu or wet relay block? just a long shot.

 

Dielectric grease is a nonconductive grease. Because it is nonconductive it does not enhance the flow of electrical current. Electrical conductors should not be coated with dielectric grease prior to being mated. However, dielectric grease is often applied to electrical connectors, particularly ones which contain rubber gaskets, as a way to provide a nonconductive lubricant and sealer for the rubber portions of the connector.

 

I've used dielectric grease for decades and will continue to do so. It seals out dirt/dust, moisture thus preventing corrosion.

Electric contacts in connectors and switches are an interference fit and therefore the grease does not negatively affect the flow of current.

From Permatex:

 

 

With that many codes all at once, first thing you have to ask is did they appear all at once? You didn't submerge it did you? If you didn't and they all came on at once then the computer is probably shot. If that CEL has been on a long time and you just ignored it then follow Frank's advise.

 

Thanks for the suggestions. I'll check it out tomorrow.
No, I didn't submerge it but it leaks in places and has lots of moisture and condensation inside at times. I don't know how long each code has been being output or in which order they appeared either.