1995 Grand Cherokee, Battery Terminals shorted together, pulled IOD fuse, no short. With fuse pulled, the ohm meter goes from dead short and immediately begins to climb in resistance like it's building capacitance. At this point I can hook up the battery and start the car with some of the accessories missing of course. This condition destroyed a brand new battery and blew the 60 amp alternator fuse. Alternator checked good after this happened. I also have no charging voltage, which is from the voltage regulator in the PCM which was probably destroyed with the infinite current draw condition. I then pulled the plugs on the PCM, TCM and alarm module, no effect. All other fuses and relays pulled one by one, also no effect on the short condition. I'm down to pulling the individual modules serviced by the IOD circuit but thought I'd see if there was a more efficient methodology. Any ideas?

 

The capactiance you're reading might be from the capacitors in the PCM being charged by the small amount of current your ohm meter is putting into the circuit. I'd inspect the regulator and capacitors on the PCM to see if they're defective. I'd also reflow the connector joints while you have it all apart as well. Not sure what else to suggest. Where are you taking your reading from by the way?

 

The PCM is unplugged and I'm reading across the battery terminals with the IOD fuse installed (dead short). With the IOD fuse removed, and the PCM and TCM still unplugged, the resistance goes from dead short and begins to build above 100K ohms. I guess I'll start unplugging everything associated with the IOD circuit.

 

 

prcherokee,

I can't do a parasitic draw test because if I hook up my ammeter with the battery leads shorted, I'll likely blow the meter (no load condition, infinite current). Thanks anyway, I appreciate any and all feed back.

 

When you connect the meter to the battery leads,you are reading the resistance of every component on car (bulbs,motors,radio and so on)an all the resistance of the wires.Watch the video.besides the worst that can happen is that you blow the fuse on the meter.
Do not be afraid is a 12V system no a nuclear reactor.