1993 dodge ram van 350

I checked the codes using the ignition on/off procedure and here's what I got:

12
23
33

Using "http://dodgeram.info/Engine-Gas/OBDI/pcm_fault_code.htm" I learned that 23 was the intake temp. sensor, so I replaced it. Problem is, *this van doesn't have AC*, so how can the PCM throw code 33? Do I have the wrong PCM code listing? How do I reset the PCM? I tried disconnecting the negative batt. terminal, but the codes were still in there, then I read that someone had to disconnect both terminals and turn on the headlights or something to reset their PCM.
Thanks in advance.

 

I'm not certain for the older vans to reset the ECM/PCM unit, but I've read where the BOTH battery cables had to be off for at least 10 mins. This drains the capacitance in the electrical system.

The Haynes Repair Manual #30065 states that 1998 to present, codes can only be removed via a scan tool. 1997 and earlier can do the battery drain.

 

Not sure what the problem is, I unplugged both batt. cables, turned the healights switch on, and let it set for 40 mins. Plugged the batt. back in, turned off headlights, did the ignition switch trick, and the codes are still there. Anybody know if pulling the fuse for the PCM would work? Which fuse is it? Getting seriously tired of seeing the Check Engine light on for no reason...
Thanks