1999 5.4 4WD ELECTRONIC NOISE COMING FROM TRANS AREA WHEN FIRST STARTING. ON OFF TYPE NOISE.

[DECOURCEY4]

When starting my expedition (168K) I get a noise midship from under the truck. It sounds like a solenoid or linear actuator trying to find its spot. When I shift it into reverse it seems to go away. Anyone have a clue? No codes and the trans shifts fine, fluid is not burnt. I did pull the transfer case fuse still does it.

 

[whtbronco]

If it's a solenoid there is likely a code associated with it so I suggest getting it scanned as the next step in troubleshooting. The only other option I have is to get under it while the noise is occurring to help isolate it some.

 

[DECOURCEY4]

If it's a solenoid there is likely a code associated with it so I suggest getting it scanned as the next step in troubleshooting. The only other option I have is to get under it while the noise is occurring to help isolate it some.

Thank you for the reply. No codes are present or pending. It sounds like it's in the trans, pass side. Noise changes when going into drive or reverse.

 

[whtbronco]

A high end scanner will read the transmissions codes, but it should also be able to show you the status of the solenoids. That might show you one that is switching status quickly. It will also show you pressure. I believe the accumulators are on the passenger side in the 4R70W and I suppose it's possible the piston could be moving rapidly, that would be odd to me though.

My original couple scanners would read the transmission codes on my vehicles. My $1000 scanner does and has saved me many thousands of dollars.

Here's an exploded view showing the accumulators, reverse is piston 7:




I don't see any way to figure this out without a high end scanner or someone with intimate knowledge of the 4R70W might have an idea.

 

[DECOURCEY4]

Thanks again for the lead! Helps a lot.

 

[mrmasa]

Thank you for the reply. No codes are present or pending. It sounds like it's in the trans, pass side. Noise changes when going into drive or reverse.

i once took the bottom pan of the transmission off, thinking i could drop and rebuild it in the lot outside my work. There were several motorized solenpid type things that do the shifting. and they can go bad. Day 3 i had towed to the shop to replace.