boost_jnky
New Member
Hello everyone. I'm new to this board. I am having a transmission problem with my Denali. The truck has 153k miles. It is a carryover model with the 5.7L engine. The transmission just recently went out with no warning due to a front pump failure. Thanks to my father I am a maintenance nut with my vehicles. I bought the truck with 144k on it and within weeks did a full tune up, had the front end rebuilt, new tires, brake inspection, and other misc interior items replaced. I am more of an import guy and bought this truck because I have always wanted one.
The problem:
My girlfriend brought the truck home one night and said that it was making a noise and wouldn't go over 30mph. I went outside and cranked the truck only to find no problem after driving it around the neighborhood. The next morning on my way to work I heard a loud whining. I pulled over and checked the power steering fluid. That is what the noise sounded like was a p.s. pump with low fluid. It was fine. I cranked the truck back up and the noise was gone. One mile up the road the trans missed 3rd gear altogether and the engine revved like in neutral. I started to pull over but was in traffic so I coasted to a stop. Now the noise was very load and coming from down low....not the power steering definitely. I managed to get the truck a mile up the road and park it at a family members house. It was now official that the transmission had bit the dust.
Fast forward:
I managed to get a used transmission from a reputable auto recycler....not a junkyard...with 90k on it from a 98 Silverado 4x4 with a 6 month warranty. With the help of a very good friend we instaled the transmission along with a new filter, front pump seal and transfer case seal. After checking all the fluids we proceeded to test drive the truck. All was great until it was supposed to go into 3rd and instead went into a free rev. We did some research on the internet and even on here. We found out that the 2-3 shift solenoid or the 3-4 clutches were most likely the culprit. I work for an auto parts supply, so I Talked to numerous shops that I deal with everyday and told them the issue. They pretty much all said the same things...but mainly the 3-4 clutches was the most common answer. I investigated further with the help of my friend. We were determined to get more answers. We found out that if you pull fuse #20 it will pull powers from the trans and make it go into manual mode and you will only have 3rd gear. This goes for all 4L60E transmissions. We tried that. It started out in 3rd gear just fine. That is the only gear it had and it did not slip one bit under light load or heavy accelration. When we put the fuse back in it has a "Service Engine" light due to the fuse pull but no 2-3 shift at all.
We determined that it had to be something electronic keeping the transmission from completing the 2-3 shift. After thinking about it for a bit, we checked the larged connector on the side of the trans to make sure that the pins are not bent. They were all fine. so we pulled the pan down and compared the solenoids from both transmissions. They were identical. I thought, since my transmission shifted fine before the front pump failed , then my electronic components are fine. We proceeded to pull every solenoid down, clean them, check them, and swap them from the old transmission to the new-used transmission. We installed them, re-installed the pan and gasket, filled with fluid, and test drove. With the fuse in we still had no 2-3 shift. We pulled the fuse and only had 3rd gear.
This is as far as I have gotten. I hope I have given enough detail to help you help me. I am stuck so any help will be greatly appreciated.
Thank you for your time.
The problem:
My girlfriend brought the truck home one night and said that it was making a noise and wouldn't go over 30mph. I went outside and cranked the truck only to find no problem after driving it around the neighborhood. The next morning on my way to work I heard a loud whining. I pulled over and checked the power steering fluid. That is what the noise sounded like was a p.s. pump with low fluid. It was fine. I cranked the truck back up and the noise was gone. One mile up the road the trans missed 3rd gear altogether and the engine revved like in neutral. I started to pull over but was in traffic so I coasted to a stop. Now the noise was very load and coming from down low....not the power steering definitely. I managed to get the truck a mile up the road and park it at a family members house. It was now official that the transmission had bit the dust.
Fast forward:
I managed to get a used transmission from a reputable auto recycler....not a junkyard...with 90k on it from a 98 Silverado 4x4 with a 6 month warranty. With the help of a very good friend we instaled the transmission along with a new filter, front pump seal and transfer case seal. After checking all the fluids we proceeded to test drive the truck. All was great until it was supposed to go into 3rd and instead went into a free rev. We did some research on the internet and even on here. We found out that the 2-3 shift solenoid or the 3-4 clutches were most likely the culprit. I work for an auto parts supply, so I Talked to numerous shops that I deal with everyday and told them the issue. They pretty much all said the same things...but mainly the 3-4 clutches was the most common answer. I investigated further with the help of my friend. We were determined to get more answers. We found out that if you pull fuse #20 it will pull powers from the trans and make it go into manual mode and you will only have 3rd gear. This goes for all 4L60E transmissions. We tried that. It started out in 3rd gear just fine. That is the only gear it had and it did not slip one bit under light load or heavy accelration. When we put the fuse back in it has a "Service Engine" light due to the fuse pull but no 2-3 shift at all.
We determined that it had to be something electronic keeping the transmission from completing the 2-3 shift. After thinking about it for a bit, we checked the larged connector on the side of the trans to make sure that the pins are not bent. They were all fine. so we pulled the pan down and compared the solenoids from both transmissions. They were identical. I thought, since my transmission shifted fine before the front pump failed , then my electronic components are fine. We proceeded to pull every solenoid down, clean them, check them, and swap them from the old transmission to the new-used transmission. We installed them, re-installed the pan and gasket, filled with fluid, and test drove. With the fuse in we still had no 2-3 shift. We pulled the fuse and only had 3rd gear.
This is as far as I have gotten. I hope I have given enough detail to help you help me. I am stuck so any help will be greatly appreciated.
Thank you for your time.
