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Chevy Silverado and GMC Sierra Transmission Problems

503 messages,  Last post on Nov 10, 2009 at 5:28 PM

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What is this discussion about? Chevrolet Silverado 1500, Chevrolet Silverado 2500, Chevrolet Silverado 3500, GMC Sierra 1500, GMC Sierra 2500, GMC Sierra 3500, Transmission, Truck

#74 of 503 Chevy Silverado 1500 4.8 Transmission fix by catfish2 Apr 25, 2007 (5:47 am)
I posted here a while back about my Transmission bucking at between 55 and 65 mph, when ever I hit a small grade. It was the Torque Converter clutch pack. I did a total rebuilt swap. I then drove the truck to Florida and Back from Maryland. Top MPG was 20.2. Most though was 18 - 19 mpg. I was loaded down with drinking water and sodas and had the pedal to the metal. 75 mph most of the way. Averaged 66.4 mph. I think thats pretty good for a full size extended cab truck. It cost 2,250 at the dealer. Oh by the way, I have 195,000 miles on that truck and the fix came with a 5 year warranty. Thanks Jeff (Service Mngr.) from JBA Chevrolet, Glen Burnie, Maryland. You dah man. Replies to this message: lroshau (Oct 05, 2007 5:50 am) bumperdude (Oct 06, 2007 11:26 am)
#75 of 503 1990 GMC 1 ton, Clutch or Tranny problem? Fuel pump stays on.... by litalow79 Apr 04, 2007 (4:57 pm)
#76 of 503 1990 GMC 1 ton, Clutch or Tranny problem? Fuel pump stays on.... by litalow79 Jan 09, 2007 (5:00 pm)
Hello, I have a 1990 GMC 1 ton truck, 454 ex-cab 4x4. We recently had a new-rebuilt motor installed and has MAYBE 300 miles on it. It had a new clutch installed as well... Now when I shift into 2nd gear it makes a slipping-whining noise, I dont know if I have a clutch problem or a tranny problem. The truck is low geared, so I mostly start out in 2nd gear. I have not noticed any problem in any other gears. The second problem is that the fuel pump will not always shut off when the truck is shut off and runs the battery down if I dont dis-connect it each night. Any help would be appreciated, thanks R.R. Replies to this message: knofler (Apr 04, 2007 4:57 pm)
#77 of 503 Re: 1990 GMC 1 ton, Clutch or Tranny problem? Fuel pump stays on.... [litalow79] by knofler Apr 04, 2007 (4:57 pm)
Replying to: litalow79 (Jan 09, 2007 5:00 pm) Have you tried replacing the fuel pump relay? It shouldn't cost more than like $12 for that model truck. If that's hanging up occasionally, it might explain your problem. Almost for sure if you've done any welding on the truck without first disconnecting the battery. Good luck!                                   Glen
#78 of 503 Allison Transmission trouble by maness Mar 30, 2007 (12:36 pm)
#79 of 503 Allison Transmission trouble by maness Feb 14, 2007 (8:40 pm)
I have 2004 2500 HD with a 5 speed allison transmission. It will not shift into overdrive until you get over 2500 rpm and you still have to let off the gas to make it go into overdrive. if you don't let up it will not shift into overdrive.I need to know if the ecu reflash will help the situation or not. It gives the trouble code p700 and also a wierd U2104 and U2105. My book does not have the meaning of these codes in it. Please let me know if you can help.. Replies to this message: kcram (Feb 17, 2007 9:06 pm) deleonc2 (Mar 30, 2007 7:49 am)
#81 of 503 Re: Allison Transmission trouble [maness] by kcram HOST Feb 17, 2007 (9:06 pm)
Replying to: maness (Feb 14, 2007 8:40 pm) U2104 CAN Bus Reset Counter Overrun U2105 CAN Bus Error ECM P0700 is Transmission Control System Malfunction   Sounds like your Allison has a computer glitch. Dealer will have to diagnose that.   kcram - Pickups Host
#82 of 503 Re: Allison Transmission trouble [maness] by deleonc2 Mar 30, 2007 (7:49 am)
Replying to: maness (Feb 14, 2007 8:40 pm) The P0700 code is the Transmission Control System- We have that code on our truck now. We have a 2004 GMC 2500 as well. If you go to Allisontransmission.com they have downloadable manuals to troubleshooting and stuff. Since our truck is over the 100,000 mile warranty, we are going to try to figure it out ourselves for now Hopefully some of what I wrote was useful.
#83 of 503 P0700 by noobie1 Mar 30, 2007 (12:29 pm)
I had this same DTC recently, but after the SES light went out I continued driving. Some time later, last Thanksgiving week, on a trip to a family gathering in Texas I got stranded in New Mexico for two days; only had Reverse and 3rd. The local dealer there couldn't get to it for a week so I opted for a very spendy haul to Texas. I expected the worst, bracing for a very hefty bill from the dealer there for a transmission replacement. Turned out to be the NSBU Switch (Neutral Safety Back-Up), $46.35 + Labor. What a blessed relief!   Now, rather last week, it returned, plus two more: P0843-Trans Fluid Press Sensor/Switch A Circuit High and P0875-Trans Fluid Press Sensor/Switch D Circuit High   I'm not sure what I'm going to do about, whether to fix it myself or let it slide. The SES light went out after three ignition cycles without diagnostic failure, and I don't drive it much any more, only about 200 mi. in the last 4 months, which may be a contributing factor. Probably the latter. I know if I were in Texas what I'd do; I'd take it back to the dealership that fixed it before. They were terrific, the rare exception; I can't applaud them enough for the way they treated me; Don Helm Chevrolet, Graham Tx.   -David

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