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Discussion Starter #1
What causes the ECU to go bad?
I have a 2007 Jeep Commander Limited 4.7L.
I bought it used a month ago. It was running rough when I test drove it. The dealer checked it out and said that it was the ECU. They replaced it and I drove it for two weeks. One night it would not start. I had it towed back to the dealer and the mechanic said that it was the ECU again. the coils were not getting the signal from the ECU. So they are waiting for a new one to replace it.
My question is ( which the mechanic couldn't answer ) what caused the ECU to fail?
 

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What causes the ECU to go bad?
I have a 2007 Jeep Commander Limited 4.7L.
I bought it used a month ago. It was running rough when I test drove it. The dealer checked it out and said that it was the ECU. They replaced it and I drove it for two weeks. One night it would not start. I had it towed back to the dealer and the mechanic said that it was the ECU again. the coils were not getting the signal from the ECU. So they are waiting for a new one to replace it.
My question is ( which the mechanic couldn't answer ) what caused the ECU to fail?
BLEE8282;

First off welcome to the forum;

As to your question about the ECU - I don't know what would possibly cause it to go bad.

However that might not be the question you should be asking.

You have to keep in mind that the newest Commander is 7 going on 8 years old now which means Commander parts have been out of production that long - your 2007 is 10 years old.

My point is that a lot of Commander parts you get from Chrysler these days are rebuilt or reconditioned parts because of how long the XK has been out of production.

So the question I would be asking your dealership is are they getting you NEW ECU's?

Or are they getting re-conditioned ECU's?

IF all they can get is re-conditioned ECU's now, and that's what they put in your XK when you had it replaced, I'd say there is a pretty good chance that's why it went bad so quickly, probably a bad or incomplete reconditioning job on that particular part.
 

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What causes the ECU to go bad?
I have a 2007 Jeep Commander Limited 4.7L.
I bought it used a month ago. It was running rough when I test drove it. The dealer checked it out and said that it was the ECU. They replaced it and I drove it for two weeks. One night it would not start. I had it towed back to the dealer and the mechanic said that it was the ECU again. the coils were not getting the signal from the ECU. So they are waiting for a new one to replace it.
My question is ( which the mechanic couldn't answer ) what caused the ECU to fail?
If the coil outputs keep burning up, I'd look at the coils as the problem.

When ECU outputs fail, it's often the part that's connected to them that causes the failure.

For example, a shorted or failing coil can overload the driver circuits in the ECU and kill that section inside the ECU.

If the mechanic couldn't explain that, I'd seriously look for another dealership/shop.

And if the coil outputs are dead on the ECU, I'd have all the coil packs tested, and if you find any bad ones, I'd probably replace all of them at the same time. The "good" ones are the same age and aren't far behind.

If the coil outputs were the issue on the previous ECU, and the coil packs weren't checked before the "new" ECU was tossed in there, I'd expect the dealership to fix their oversight and replace the ECU (warranty or service policy, their choice), after they test all the coil packs. I wouldn't expect them to pay for the replacement coil packs, but I would expect that they'd pay for the tow and do something (discount, courtesy car, whatever) for the inconvenience their incomplete diagnosis caused you.
 

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Discussion Starter #4
Thank you guys for your help.
I will ask if the unit was "New" or reconditioned.
The first ECU allowed the engine to run. It just had a rough idle and sputtered when put into gear.
With the replacement ECU the Commander would not start at all.
I will call them and have them test the coil packs.
Since it had low miles for its age I thought I would gotten a better running vehicle. It has 100,200 miles.
 

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Many ECU failures can be attributed to bad solder joints (cold) where the ECU connectors are soldered to the internal circuit board. The solder connections due to vibration etc. can eventually crack and cause intermittent connections etc. and strange misfires or weird engine behavior. I have repaired several bad ECU's by re-soldering the circuit board connections. Sometimes just flexing the connections on an ECU can get you going again and perhaps get you home.
 

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Discussion Starter #6
Question?
Will a ECU / Computer from a 2006 4.7L Commander Limited have to be flashed if its going into my 2007 4.7L Commander Limited?
 

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Yes, at the very least, VIN and milage should be flashed over. If you just drop that ECU in there and try to start, the ECU will perform a VIN check with other parts, fail, and just won't start.
 
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