Here's the story:

1995 Montero LS 3.0L V6. Vehicle died in my garage. Cranked but wouldn't start. The coils were fried, as was the ignition module(?).

My independent mechanic replaced those and the vehicle ran for about 100 miles, then died on the road. Towed home. Checked the coils and the ignition module again. Fried. Replaced them and replaced the ECU with a used unit. Vehicle started. Ran for 30 minutes and died during my mechanic's test drive.

My mechanic has no way to test signals upstream of the dead ECU so I had the Montero towed to a Mitsubishi dealer shop. A WEEK later, they tell me the ECU is toast and that a new ECU would be over $700. I had told them we knew the ECU was dead when I brought it in. I needed them to find out WHY the ECUs are getting fried. They said they can't tell me any more until they put a new ECU into it.

Huh?

Can anyone give me and my independent mechanic any insight on how to find out what's killing the ECU? The Mitsu dealer isn't telling us anything we didn't already know and they have had the vehicle for a week.

I love my '95 Montero and need it back on the road!

HELP!

A new ecu for 700$ is about right, however I would not let them put one in. If they do, it will fry again and they wont cover the 700$. I say hit a u pull it and grab another ecu or two. Swap it in and drive strait back to the dealer? Then see what they say? They need it running to diagnose, so get it running for them.

Check the ISC/IAC.

remove alternator and test it for excessive voltage. Remove and test idle control motor (known to fry ecu's). Test control relay by removing and testing for shorts. Does this motor have a single coil or coil pack? You can check wiring harness for shorts to ground.