Chrysler Repair: 94 Chrysler Concorde 3.3 electrical problems, chrysler concorde, oxygen sensors

Question
Hi Roland ,
The car was running fine, then would turnover but not start.  Initially the "Check engine" and other dash lights would not come on when turning the ignition on so I could not get the diagnostic code. I began testing the ignition switch. I pulled fuses 19 (air bag- tested at 12v) and 20 (radiator fan tested at less than 12v) when I turned the key to check voltage my dash lights came on and the car started. If I tried to put the air bag fuse in while the car was running it would continue to run and the air bag light would go off. But the car would not restart until I pulled the fuse. If I tried to put fuse 20 in the car would die immediately.  With the fuses out I was able to get the following reading.  12 33 35 35 31 32 55. I checked grounds and wiring connections and now I’m getting a 77 code as well as the others.  I have a book so I know the codes are AC, Fan, EVAP, EGR, and speed control.  As long as I don't put the fuses in, the car runs but the "Check engine" AND "Air bag" light stays on. Do I have a computer problem, ignition switch, or is it more likely a wiring problem?

Answer
Hi Brian,
Those two fuses, 19 (air bag) and 20 (A/C clutch, both fan relays, evap, manifold, egr solenoids, oxygen sensors), are both powered by a section of the ignition switch that also runs the ASD relay (fuse 18) and the body computer/message center (fuse 17). It appears to me that some item being powered by fuse 20 is overdrawing the circuit but not blowing the fuse. So I would measure the ohms that fuse 20 is looking at and then try unplugging those several items one at a time to find out which one it doing the excessive current drawdown which would be revealed by a jump in the ohm reading when it was unplugged. It may be problem with excessive resistance to current flow in the ignition switch section (A1 to A21) but that is the second line of approach. I doubt it is the computer itself, or the body computer. It could be a short in the wiring to one of the items on fuse 20 if not the item itself.
Please let me know what you learn. Thanks for the detailed history.
Roland