4L60e Won't Stay in OD or Downshift from 3rd While Moving
01-18-2017, 10:56 PM
#1
4L60e Won't Stay in OD or Downshift from 3rd While Moving
Hey guys, I got a 2003 Silverado RCSB Z71. I bought it a few months ago, had 190,xxx miles on the clock, I put maybe 4k miles on it since. Runs like a top. I do some towing, but it's been almost a month since the last time.
Today on my 10 mile drive to work I noticed it not shifting into overdrive or downshifting automatically down into 2nd when passing or even WOT. It will downshift if I manually select with the gear shifter. It seems to shift normally 1-2 & 2-3. It also returns to 1st gear at stops. No SES lights....
When I got to work I pulled out my Harbor Freight scanner and checked for stored or pending codes.....none. I also checked the transmission fluid level and color. Both are spot on, it fact the transmission fluid looks brand new. Before I bought the truck I crawled under it looking for leaks, etc and noticed tool marks on the bellhousing bolts, so it probably means the transmission has been rebuild somewhat recently.
After work I noticed it will shift into overdrive while coasting downhill without any throttle, but the instant I barely touch the throttle.....no load whatsoever.....it downshifts to 3rd.
I recently moved to the area and don't know anyone with a higher end scan tool to see if if the PCM is actually commanding the shift or not.
Any other ideas? My first thought was shift solenoid, but that's usually means a code or two popping up. Plus usually I thought you lose 1st gear too with a bad solenoid.
Any help is thanked in advance.
Today on my 10 mile drive to work I noticed it not shifting into overdrive or downshifting automatically down into 2nd when passing or even WOT. It will downshift if I manually select with the gear shifter. It seems to shift normally 1-2 & 2-3. It also returns to 1st gear at stops. No SES lights....
When I got to work I pulled out my Harbor Freight scanner and checked for stored or pending codes.....none. I also checked the transmission fluid level and color. Both are spot on, it fact the transmission fluid looks brand new. Before I bought the truck I crawled under it looking for leaks, etc and noticed tool marks on the bellhousing bolts, so it probably means the transmission has been rebuild somewhat recently.
After work I noticed it will shift into overdrive while coasting downhill without any throttle, but the instant I barely touch the throttle.....no load whatsoever.....it downshifts to 3rd.
I recently moved to the area and don't know anyone with a higher end scan tool to see if if the PCM is actually commanding the shift or not.
Any other ideas? My first thought was shift solenoid, but that's usually means a code or two popping up. Plus usually I thought you lose 1st gear too with a bad solenoid.
Any help is thanked in advance.
