An older thread (Best model year for XJ? by MINI XJ) states in post #18 that California Renix Xj's post 1988 had OBD1. Can anyone verify this and explain how it works? My 89 has no check engine light to my knowledge.

Look under the dash for a odb1 port.

That't OBDII. OBDI is under the hood hanging from the PCM. I don't know anything about renix-era jeeps but I have a hard time believing an 89 is OBD1.

Never.

Diagnostic ports are located on passenger side fender wheel in engine compartment by the bank of relays. 2 yellow caps cover ports.

Short answer, live data only, can't store or produce codes.

Good video of scanning a Renix: