What does disconnecting the batterys do to the ECM?

[Tom W]

I have heard comments about this. I disconnected my batterys overnight to clear a check engine light and now it runs different. It seems to have the same power (maybe slightly more) but the engine noise is definately more. I have been fighting the dreaded drone at 2200 RPM and got rid of most of it but now it's back with a vengence, starts at 1800RPM when accelerating. Anybody got any ideas about this? Will it ever get back to where it was?

Thanks for any ideas. Tom

 

[Gizmo 007]

Read the "Dodge one up'd us again" thread. That aught to help you out.

 

[Vaughn MacKenzie]

I did the same thing to try and get mine to run better (rough idle). Had no effect whatsoever. Same power, sound, attitude. Wasn't worth the hassle doing it and resetting my clock and losing my trip odometer mileage (to compute MPG).



Vaughn

 

[jwilliams3]

Removing power supply from your ECM while the engine is shut off then reconnecting will have no effect on performance of your engine.



The ECM is like a calculator or VCR it works while power is supplied and does not lose or gain anything with a power loss.

 

[Paul Somers]

GM ECMs learn and I'm sure the Ram does also. The look up tables change as engine operating conditions change( different grade gas, pulling trailer etc ). After pulling my 10,000# 5th wheel it takes several miles of not pulling before it re-learns. On my previous GM the transmission didn't shift right for about the first 30 miles after pulling. Disconnecting the battery restores the tables to default.