Took a trip yesterday ('bout 150 miles) and all was fine. Came home parked her, then went out later. When I first left the house all was fine, then came to a stop sign, while waiting for traffic the truck bucked a little bit, and when I took off was low on power. After several more stop signs, notices it was taking off in 2nd gear. Would take off in 1st gear if I manually shifted it. Upon arrival to my destination pulled the codes and got a P0500.

A few searches on here, it appears the p0500 is related to the vehicle speed sensor (is this the one in the rearend?) and that perhaps due to this the tranny is in limp mode (although I never exceeded 40mph I swear it was locking up in 3rd but I haven't gone fast enough to see if OD kicks in).

Last thing I did to the truck was the Vulcan kit and its been running great since then.

Should I stop by the local parts place and get a vehicle speed sensor? Just looking for confirmation on my thought process here. Any input is appreciated.

 

Maybe my code isn't related? Further research shows the P0500 code may set with a wheel spin I have done this a few times testing the "traction" on my new tires. This makes sense as my speedo is working just fine.

Guess I'll clear the code and see if it returns for now. Guess I must go do a real test drive to see if I'm in full limp mode with no OD, then re-read all the threads on 47re limp mode.

 

Okay, cleared the P0500 code and took her for a drive. After further driving, it is taking off in 3rd gear, not 2nd. If I downshift to "2" she takes off in 2nd, if I downshift to 1, she takes off in 1st.

If I downshift to 1 and take off and put her in "d" she seems to skip by 2nd and go straight to 3rd.

OD and lockup are working fine. I've checked under hood fuses with ohm meter, fine. Swapped "trans" relay with wiper motor relay, and no change in symptoms.

Trans fluid is pretty red, no smell, and full. Also, the P0500 didn't come back after about 10 miles of driving and testing.

So it appears the code was unrelated, and I'm now at:

A tranny that wont upshift automatically. It will downshift from 3rd to 2nd if I get on it.

Oh, and if anyone is interested, batteries test great, charging seems fine, and the terminals are clean and shiny.

Unfortunately it looks like I may have a trans issue as I think I've ruled everything else out. Again, any input is appreciated.

 

I would believe that the P0500 was unrelated, especially if you haven't noticed your speedometer not working. The transmission, having its own output speed sensor, is not usually affected by a lack of VSS signal.

The starting in 2nd or 3rd gear is a common complaint, and while I prefer to diagnose them with a scanner, the root cause has always been a failed governor pressure solenoid or governor pressure transducer. These two components live on the side of the trans. valve body, can be replaced after removing the trans. pan, and are relatively inexpensive. I usually change the two together on a problem vehicle.

 

Would a DRB scanner give the answer? I do have a friend with the high $$ scanner.

Alternately it is about time for a fluid/filter change anyway (I'm at 55k), should I take her in for this and just suggest changing these components?

 

PM scottsjeeprolet and see when you can use his lift. We can all come by and learn something.
We can drop the pan , and replace the governor pressure solenoid and the governor pressure transducer, then see what happens.
We are always up for a new challenge.....

 

I may do that. I know someone with the fancy scanner that I may stop by today and get a diagnosis, but I'm sure torquefan is right after more research, I just couldn't figure out a good search term yesterday to find the problem. After using those parts terms, all symptoms seem the same as other folks'.

 

Governor Pressure Sensor and Govornor Pressure Solonoid.

Just had mine replaced on Thursday after living with that very problem for 3 weeks.

Dealership wouldn't take my word for it it was those two parts,
it had to throw the codes before they'd believe me.


phox

 

Good call, guys.

 

Just an update, the governor pressure solenoid and transducer fixed the issue. Went over Scottsjeeprolet's house yesterday and he graciously assisted with his garage and lift, and we changed out the parts. While the pan was dropped we adjusted the bands, changed the filter, and buttoned her all back up. Took her out for a road test, and viola, all fixed!

Pretty easy job (except for the mess of dropping the pan). Since we had just met we spent a lot time just chatting and it still only took us a couple hours.

So thanks to all for their input, you were all spot on, and again thanks to Scott for his assistance!