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I have a 2004 Chevy Astro van 2WD 4.3L with a 4L60E automatic transmission and something is seriously wrong, but I have yet to figure it out. I definitely need some help. I usually do all my own repairs and I am very mechanically inclined, but this has me stumped. I even consulted a friend who knows a lot more than me and he was puzzled and asked that I share with him what was wrong once it has been diagnosed. I would probably be willing to drop the big wad of cash down for parts for a remanufactured transmission if needed, or for a remanufactured rear end and new axles.... BUT the van is not worth spending $1,500 (or more) times TWO. I need to definitively be able diagnose the problem so that I can decide how much I'm going to have to invest to get it going again. I bought it used from a municipal police department that used it as a crime scene investigation vehicle and it has no hitch on it, so to the best of my knowledge it has never done any towing. Here is what happened and what I have checked thus far....
I pulled out of the driveway at work and after I had cleared the 2 lanes of oncoming traffic and was in the crossover in the median I let off of the accelerator and heard a slap, pop, or bang that sounded like it came from the right, rear corner. I instantly thought it might be trouble as it sounded like clapping/slapping two solid bricks together. I hoped it was just something I ran over. Then I pulled out and accelerated up to 55 mph. Then about a 1/2 mile down the road I heard what sounded like driving on a tire that was completely flat. I pulled off the road to check out my tires. I was surprised when they all looked fine. I realized something had to be wrong and I wanted to get my van to a better spot where I could investigate further. I put it in reverse to back up a few feet to better align me with the area I wanted to drive to, but the van would not move backwards. I wondered if something with my rear brakes had broken or locked up. I was able to move forward in D, but there was a good amount of resistance as the engine was struggling to move the van forward. There was a good clear spot nearby where I parked.
I thought somehow something had broken in the rear brakes and bound things up preventing the van from moving as normal. I jacked up the van and removed both of the rear wheels, removed the pads & rotors, then propped the calipers out of the way. I put the transmission in neutral. I replaced the rear wheels as it was easier to rotate the tires by hand than trying to rotate the lugs on the hubs by hand. The tires spun freely by hand, but after about 10 revolutions there was a clang noise and the tires stopped. I rotated the tire in the reverse direction and it no longer made the driveshaft move as it had been in the forward direction. Then the clang noise again and the tire stopped rotating in the reverse position. Both front wheels easily rotated when spun by hand, so the binding wasn't coming from the front
This made me think that it was possibly something going on in the rear end. I pulled the cover and I saw no obvious problems with the differential. I have the G80 rear end which I had never seen that type of rear end before. When I moved my tire forward by hand slowly there was no movement in the rear end, but when I put my foot on the tire and give it a spin the tire moved a lot and the rear end moves a little. I didn't see anything that looked worn or damaged in the rear end. I cleaned up the parts, cover, and magnet and put the cover on with a new gasket and replaced the fluid. While both the rear wheels were still off the ground I cranked the van. It was still in neutral, but both rear wheels were slowly rotating forward. Then I shifted into Drive and, with the engine idling, the wheels would pulse several rotations forward, then slow to almost a stop and then repeat the pulse & near stop. I couldn't understand why the surge and slow was taking place. Then, I drove it the 1/2 back to work to leave it in their parking lot. The van made all sorts of popping, grinding, and clanging noises. When I stopped I put the transmission in neutral, but it would not roll backwards. I tried reverse and the nose of the van dived down and the rear bucked up, but the van never traveled any distance in reverse. I pulled it forward a few feet into the nearest parking space. The van did throw a MIL code on the way back to work, which was a P0756 (PCM sensed an irregularity in shift solenoid B).
I thought that I might need to remove the driveshaft and see if the transmission would turn the output shaft while in reverse. Also, I could try to see if there were and weird noises, pulsing, or resistance to the output shift turning when in Drive. But, I wouldn't necessarily know for sure the tranny was good if it only misbehaved while under a load.
I had ordered a set of shop manuals about a week before all this happened, and they have now arrived but I wanted to see if anyone had any ideas about how to diagnose my problem before I resorted to the shop manuals. I get bogged down in them because there is soooo much information in them.
How can I definitely determine if the problem is my tranny, my rear end, or both?
Here is a video link on YouTube showing when I had the rear end cover removed:
Here is a video link showing when the rear end cover and fluid were replaced and both rear wheels were off the ground in Neutral and in Drive with the van running:
By TruckGuy 94
I have a 2011 GMC Sierra Denali with a park assist problem I’m hoping someone can help me solve. A couple months ago, I started getting a sporadic “park assist blocked” error. This is pretty common as the sensors are covered in snow in the winter. However, I then noticed the sensors began to work sporadically even if they were clear. A month or so after that, the message changed to “service park assist” and the system automatically disables itself. The button on the dash shows the system is off all the time and when I try to turn it back on, the orange light flashes for two seconds but then disables itself again. I’ve checked the fuse and unplugged the battery but have not been able to get it to reset. Does this seem like a sensor issue or a control module? Any ideas for next steps? Unfortunately since the system is disabled all the time I can’t check to see if one sensor is malfunctioning as I’ve read about on other forums.
Update: when I started my truck once this week it randomly worked for 10 seconds then disabled itself again and hasn’t worked since.
I know there are a few different forums on this topic, but they seem to have gone dead. The steering in my truck clicks and clunks especially at low speeds, and the truck wanders on the highway. I am constantly holding the wheel to the left or right to go straight. I have had the intermediate shaft replaced per the service bulletin. After it was replaced some of the noises were reduced, but not eliminated and the truck will still not track straight especially at highway speeds. It almost feels like a bad tie rod end or ball joint, but the dealership said everything is nice and tight, and I checked just for my sanity. I also added a steering stabilizer in hopes this would help. Is anyone else having these issues, and have you been able to get them fixed?
2020 Silverado LTZ with 6.6 DuPIT5809.pdframax
I have a lifetime warranty on my Truck, I am tired of the electric noise , “super quiet”. I want to throw some cat back exhaust on, resonator delete or a new flow master 40, something , with a 6inch tip, Welllll the dealer told me to call there warranty people and the warranty people said any modifications to that part of the vehicle WILL void the Lifetime Warranty, I already had a new tranny rebuilt and new driveline:differential seal installed also wheel bearings ALL UNDER LIFETIME WARRANTY, So it has been a huge help, So can I or can I not do a simple exhaust without voiding my lifetime warranty ??
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