Any reason a bad ecm/ecu code would come and go?

[cclayton]

I looked at a 2007 ram 1500 4.7 4x4 6 speed manual at a dealership today. It had only 59,000 miles. The dealer was kind enough to let me know that a light on the dash had been coming up throughout the last couple days and upon plugging in the scanner it came up with bad ecm or ecu (I can't remember which). I took it on the test drive and didn't ever see a light on and the engine seemed to run good, surprisingly having plenty of power being a smaller 4.7. Any ideas why a code like that would pop up and come and go? It's been raining crazy here in Iowa lately.

 

[MikeT]

Possibly a corroded or loose ground. Those kinds of things can reek havoc in a vehicle and they may be difficult to find. Fixing isn't bad once found. Good Luck.

Mike

 

[17CrewCab1500]

My wife has a 2006 Dodge Durango with the 4.7. Really good motor. In fact, she has over 255K miles on it.

Recently she had light come on and go off maybe a week later. The code I got was random cylinder misfire.

A buddy of mine knows I take care of it and change the plugs at 30K religiously.

So he said replace the ECU. I bought one just last week from carcomputerexchange.com and had it shipped in 2 days.

It took me an hour to do, very easy. Youtube has some great videos on it.

Haven't had any issues since and it does seem to run alot better.

So, it's possible.. with the ECU and coming/going.

 

[JohnnyMac]

Certainly could be a bad ECU like @17CrewCab1500 says, but before you pull the trigger on a new one, I'd do what @MikeT suggests by chasing down your grounds and also check the battery itself. These Rams get real wonky (technical term) when the voltage levels aren't nice and strong. An easy check is to put your volt-meter on the battery and have someone turn it over. If the voltage drops below 10.5 volts while cranking then most likely the battery is old and tired. On a side note, a bad starter could cause this same symptom, but if it's turning over fairly easily your starter is probably fine.

Good luck and please let us know what you find.

 

[MADDOG]

In addition to the grounds and battery, check your main harness PCM connector for damage (cracks), water or corrosion inside the connector at the harness end and the PCM end and make sure the connector is secure.