This is my code. What is the name of the part I actually need to replace?

Gear position sensor?
Park/neutral position sensor?

My googlefu is not helping me figure out what to replace or even what it is called.

This site lists it as the PNP switch.
GM Trouble Codes - 2 digit codes
Is there only one code stored?

Yup, the paperclip secret handshake gives me a code 12 and then the 31.

Happened after punching it on an on ramp. Guess some old sensor gave out, I'm just having a hard time figuring out the part number what what I need to order.

A code does not tell you what to replace.....what it tells you is that there is a problem, somewhere, in the "whole" circuit, which means the wiring and the components the wiring connects....

This involves the PNP switch, or Park/neutral switch which located on top of the tranny, below the manual linkage......it could be that switch, the ECM, or any one of the circuits out of the switch to the ECM.....

See...that doesn't make me happy.

If I can't troubleshoot it or fix it myself, it doesn't get fixed.

Being broke sucks.

I would start by closely inspecting the connector & wiring to the PNP switch.
Remove the connector, have a look inside pins etc for oily deposits.
You could use some electrical contact cleaner/compressed air, re-connect/clear codes and see if that helps.

You can troubleshoot it yourself......but you need a multimeter, a wiring diagram, and the ability to read the diagram.........basically you will have to disconnect the battery(key out of ignition), and disconnect the harnesses to the ECM, and troubleshoot the circuits between the PNP and the ECM....

To do this, you will now have to insert the key(battery still disconnected), and go through all the shift points(ebrake should be on so car will not roll.....block wheels if necessary), and test each circuit at the ECM harness..........if all circuits test out, you need an ECM.....

But as Soft Ride stated, your first move is to do a visual inspection of the harness and the connectors....

Also, the PNP could be out of adjustment....a quick check would be to see if your reverse lights are on when the shifter is in R.....

Problem solved, gummed up connector. Cleaned up and no more DTC 31. Woo!


Day later: DTC 41. Dammit car! Stop breaking faster than I can fix you!

I think 41 may be a Cam Sensor Signal error. Being a 92 it may have thrown the magnet from the holder.

X2 as above
Look at the bright side, it is one down,one more to go!
Considering it now is ignition control related, how is the car running?