O.K, I'll have to describe this the best way I can. I have a 2007 1500 Hemi, 103,000 miles. I've been getting this very sparatic clunk sound from engine. Driving not under a load, kind of when just coasting along. Almost only happens when the truck kind of wants to be in the next gear due to the speed your traveling, but doesnt shift up because your not giving it enough gas to shift, if that makes sense. Does not make the sound when I punch it or in the higher rmp's. It will only clunk once or twice. But two times recently it clunked about 10 times in a row, as soon as I ook my foot off the gas it stopped. I maybe was thinking it had something to do with the mds? Because that is when it would happen, when your going along 25-30 mph with no load on motor, when the mds would be on. Today I as driving and it clunked again, about two clunks per second. Today it lasted the longest about 30 clunks, this time when it was doing it I hit the button and went into tow mode turning off the mds and the sound immediately stopped. update: Today when I drove the sound happened again. Doing about 25 mph, this time I accelerated when I heard it and it stopped immediately.

 

it might have something to do with the solenoids for the MDS.

 

My check engine light came on about two weeks ago stayed on for 2 or 3 days then went off. Would a soleniods throw a code out?

 

Yes the solenoid will throw a code if there is an issue. The one code I'm aware of is P3400.

On my truck I got this code, because the engine was over due for an oil change. MDS needs good oil to function properly.