I have a Dodge Grand Caravan 2001 that was having running rough and the exhaust smelled like raw gas. I replaced some sensors and that didn't work so I decided to replace the ECU. I got a new ECU from FlagshipOne and put it in and now the car won't turn over at all. I put the old ECU back in and get the same result. What should I check now?

Also, the battery is not an issue. I charged it up and nothing changed.

Update: I waited a little bit and then tried starting the car again with the old ECU. It started up but still had the rough idle, etc... So I put the new ECU in, waited, but it still will not turn over with the new ECU. I can hear the fuel pump run and I can get the live sensor data with a OBDII tool but it still won't start.

  • So, when you put the original ECU back in, does "same result" mean same result as original ECU, or now the original ECU is not allowing it to turn over? Please edit your question to clarify. Welcome! Commented Jul 21, 2021 at 23:59
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    @MarkStewart I've since waited a bit and then tried to start the car again with the old ECU. Then it started. So I put the new ECU and no start. So I waited and tried again but it still won't turn over. Thanks! Commented Jul 23, 2021 at 4:08


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