[KathyP]

Hi. I've got a 2002 1500 5.7 automatic, 168K miles, original owner. Lately it started running rough when in gear. Vibrating a bit. When I shift it into neutral, like going down a hill, the roughness stops. My husband says it's probably transmission problem. The check engine light is on, but when I took it to AutoZone, the code is for a fan relay. The transmission fluid hasn't been changed in several years. Any idea if it is a transmission problem? I'm sure it's overdue to get the fluid changed out, which I will do. Any other ideas? Thanks.

Kathy

 

[bigdaddyII]

Hi Kathy, welcome. Either your truck is a 2002 5.9 liter or a 2003 5.7 liter. The 5.7 hemi wasnt offered in 2002.

When was your last tune up done? I doubt you issue is a transmission problem, based on the information you gave I would guess it could be a vacuum leak, dirty sensor (MAF, TPS, etc) or the throttle body and/or EGR valve needing cleaned. The reason it smoothes out when you put it in neutral is because even though the engine may not be doing any work (coasting down a hill), being in gear puts a load on it and when you shift into neutral it takes the load off of the engine.

 

[KathyP]

Thanks for the info, BigDaddyII. I will keep in mind. Further explanation from husband: He says it rumbles at about 45 MPH, as in when shifting when in 4th gear. He said something about 'bands.' He still thinks tranny. I hope not.

Make any sense? BTW, my truck is the small V8.

 

[bigdaddyII]

In 2002 the "small" v-8 would be the 4.7 liter, with the 5.9 liter 360 offered as the larger option. The 5.9 liter had the 46RE transmission behind it, which did have adjustable band that are supposed to be adjusted at every transmission fluid/filter change. However, if you do have the 4.7 (going by the smaller V-8 comment in your previous post), this engine has a 45RFE transmission behind it which only requires fluid/ filter changes and no adjustment.

Could you find out specifically which engine you have in your truck? Its really difficult trying diagnose something if you dont know exactly what you are dealing with. There are vast differences between the 5.7 hemi, 4.7 liter, and 5.9 liter, especially regarding drivetrain in the 2002 model year.

 

[KathyP]

BigDaddyII - Sorry for the confusion on my part. It's definitely a 4.7 liter engine. Rumbling at and above 45 mph. not when moving in neutral, however. Thank you.

 

[bigdaddyII]

Okay, the 4.7 liter has a 45RFE transmission behind it. This transmission does not require any band adjustment. I have serviced the fluid/ filters on my 02 4.7 liter 3 times and didnt even see a way to adjust anything.

What do you mean by "rumble"? If it sounds like it has mud tires on it at speeds of 30 and above a wheel hub may be going bad and needing to be replaced. Universal joints will make the same noise as well.

The original problem you posted about still sounds to me like it needs a good tune up and the throttle body cleaned.