01 Rio - blows ECM fuse

[alexrichardson]

All,
working on my son's 01 Rio. Symptoms so far:

Car died while driving - son found blown ECM fuse and tried replacing it. Eventually went from the stock 10A to a 15A and got car to start. 15A fuse blew as soon as he put it in gear.

I replaced the ECM with one from a junkyard. Car started and ran long enough to drive it down the driveway before 10A fuse blew and car died.

Now, with a 10A fuse and they ignition key 'on' but not trying to start engine, I hear a buzzing noise from under the hood. As near as I can tell from looking at the diagrams from the kiatechinfo.com site, it's the ISC solenoid valve. When I remove the connector from it, the buzzing stops.

Does anyone have any other ideas or similar experiences before I go buy another part hoping it will fix it?

thanks.

[alexrichardson]

In a nutshell, it was a worn spot in the wiring under the hood causing an intermittent short.

Longer version – I tried replacing the ISC / IAC (same part, different names) with no change. What I did notice during the continuing troubleshooting was that the fuse actually blew when the engine rocked forward on the mounts after putting it in a forward gear. Tracing the wiring, my son found a worn spot in the harness where the transmission housing was shorting a line leading to the alternator. We fixed and rewrapped both the green/white ECM line and a white/red line feeding the instrument panel which had been worn almost completely though. This solved both the ECM fuse issue and seems to have cleared up an intermittent flickering Check Engine and Parking Brake indicator light problem we’ve had since we bought the car.

Based on the design, I doubt we’re the only people to have this issue. Hopefully this info will help someone else in the future.

-alex