Hondata

I can check each wire end-to-end for a good connection, but to verify wire routing I have to have a wiring diagram for the harness. There has to be a wiring diagram, the manufacturer has to have one and I'd bet Hondata has one (since they require the adapter harness for my Hondata application).

My dealer is going to send a new harness and contact the manufacturer for a diagram. If the new harness doesn't work, by process of elimination, the problem is the ECU

The OBDI wiring diagrams are here:
http://www.hondata.com/techwiringgsr.html

We don't have the OBDIIb diagrams on the web. However, here are the pins which you might need to look at:

MIL A13 (OBDI) A18 (OBDIIb)
ACS B5 (OBDI) A27 (OBDIIb)
ACC A15 (OBDI) A17 (OBDIIb)

excellent, thank-you, that saves me the work of digging into the wiring diagrams. I'll check the connections you listed.

Thank-you Hondata, I stand corrected.

I got a new harness and the problem went away. So anyone else with CEL when A/C is on problem... it's your OBD11 to OBD1 conversion harness.

The harness manufacturer is investigating the defective harness