Jump to content

'00 C1500; issues with torque converter lock-up

toaster-pastry

By toaster-pastry
in Ask A GM Technician

Recommended Posts

toaster-pastry New Member

toaster-pastry

Posted
Posted

Hello,

 

I'm having some issues with my Silverado and I would really appreciate some insight. I searched around, but it appears the issues have not been covered. I also read the rules, so I hope I am doing this right.

 

2000 Silverado C1500

1GCEC14V8YE14****

4.8litre, automatic, 2wd

63k miles

-optional OE heavy-duty suspension package

-285/65R16 tires (over-sized slightly)

 

There are two main issues, both of which seem to be related to the lock-up torque converter. They are consistent and have been there since I bought the vehicle last year (with 60k miles).

 

When driving along specifically around 50-55mph, the truck will be in overdrive and the torque converter will lock. This creates too much load on the engine for the speed, so the truck unlocks the torque converter within five seconds. This becomes a continuing pattern: lock, unlock. Lock, unlock. It goes back and forth very frequently sometimes within a second of each other. It really just seems like the shift points are all messed up. The transmission operates perfectly in tow-haul mode (little button on the shifter), and I have almost got into the habit of using the tow haul mode every time I drive. I am also only getting an average fuel economy of 13mpg.

 

Second, and possibly related: I like to use my parking brake when I park, especially on hills. This is suggested in the manual and just makes sense, however I am unable to use mine. This is why:

 

When I come to a stop, I hold the brake, set the parking brake, then put the vehicle in park. The idea is to prevent excess stress on the parking pawl. Every time I do this, the next time I start the engine, the vehicle lunges forward like it's still in gear and the starter is moving the vehicle. (Torque converter clutch still locked?) The same thing happens sometimes when you shut the engine off while the truck is in neutral, then place it in park, and then start it again (without using park brake)

 

The only for sure way for it not to happen is to put the truck in park, let off the brake and load up the pawl, then turn off the engine.

 

I am a mechanic and have investestigated the issues myself and turned up empty handed. There are no TSBs on the issue. The only thing I can think of, is that there was a Hypertech sticker on the truck when I bought it. Is it possible that someone has "chipped" the truck and modded the TCC lock up or shift points?

 

otherwise, the truck runs great and is very well maintained!

 

thanks for the help!

 

T-P

toaster-pastry New Member

toaster-pastry

Posted
  • Author
Posted
Sounds like an ECM issue to me. Have your dealer check to see if your chips have been changed. If not maybe a -reflash or update will solve tha issue.

 

 

Thanks, but I think I figured out the issue over the weekend. I dropped the pan to change the transmission fluid and filter, but was greeted to a pan and filter filled with broken pieces from a needle bearing and a ton of metal shavings on the filter. I can't belive it! 63k miles and the transmission is toast. d**n, I need to trade this thing in on a new Toyota Tundra and get some quality :shakehead:

Norseman Senior Enthusiast

Norseman

Posted
Posted
d**n, I need to trade this thing in on a new Toyota Tundra and get some quality :shakehead:

 

 

Whatever man, just do it then and put us out of your misery. I've had plenty experience with Toyota's cr@p and if you think you're gonna get better then do it and go hang out with the Tojo crowd. I know it’s agravating when something happens, but please take that sh!t elsewhere.

Nice rig Enthusiast

Nice rig

Posted
Posted

#1, you bought the truck used and have no idea if the guy before you beat the hell out of it or maintained it. #2, every automaker has things go wrong and break...if it's mechanical it'll break no matter what you try to do.

Have a nice day. :shakehead:

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • asilverblazer
      Slate Electric Truck

      By asilverblazer · Posted

      I like the idea.  I would pick diesel if I had a choice. I need pictures though.
    • newdude
      Help purchasing a touch screen digitizer

      By newdude · Posted

      I've installed cheap eBay new aftermarket digitizers before.  They work.  Did a bunch of Cadillac CUE (aka Cadillac's MyLink) for someone years ago.  They all worked fine after the repair.    That number 22740886, that is a component part # for GM.  You can use it to search, but its not something that's obtainable at the dealer level.     So pretty much any of these will work - 2015 Colorado Digitizer for sale | eBay
    • asilverblazer
      give me some tips to make my truck look better

      By asilverblazer · Posted

      Black bumper and the later years Z-71 style color matched grille.
    • fondupot
      Exhaust heat while towing!

      By fondupot · Posted

      You can install tailpipes that direct the exhaust sideways vs the OEM one that goes straight back. There are several on the market, do you own research. HOWEVER, you need to make sure the Venturi vents are still intact, otherwise it will throw a engine code. There is a sensor somewhere that detects back pressure on the exhaust. And if it doesn't collect the correct metrics, it will throw the truck into limp mode. 
    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      "Teardown" is complete. Head surfaces are clean and ready, new intake is prepped and ready. Coolant drained and water pump is removed, radiator is removed, new hoses and pump are ready.   The replacement intake is also from a '95 (with I think 260k, the odometer said). Noticeably less pitting where it covers the rear coolant passages. I'm not sure if that's a tribute to more frequent use, more frequent coolant changes/upkeep, or if the intake was machined at some point. But it appears I found a good one.   My coolant hoses were original, and the lower hose still retained the factory spring inside. It's not really rusty, but it's got deposits all over it. Unsure if I should re-install it (will thoroughly clean it first). Someone said hose technology has gotten better since 1995 (has it?) and I don't need the spring. I think modern EPDM is what made those hoses last from 1995-2026, so it's a question of how much suction can the water pump really pull, and will it collapse the hose without a spring?   I'm stopped and waiting for parts, however.   When I first brought the truck home, the fan was intermittently hitting the radiator shroud. I could see someone had monkeyed with the shroud (put a bunch of cardboard as a spacer between the upper/lower shroud halves. Someone said the motor mounts have likely failed and the engine has sagged. I wasn't sure I believed that. The engine is really solid in its mounts: To remove the old intake I *just* nearly permanently welded to the heads with freshly cured RTV and gasket snot two weeks ago, I literally had to use the arms on my lift and a chain with a bolt attached to the intake to pull it loose. It almost picked the front of the truck off the ground before ....scuuuuuuuuuuup.... I could actually hear the gaskets tearing and it broke loose and the whole truck settled back down. Motor barely moved.   SO, those parts I'm waiting on... The lower radiator mounts/bushings had completely failed. The radiator needs to be insulated from the rad support, and the bushings help the rad stand at the correct height. The plastic "baffle" was also destroyed at some point. Someone had attached the shroud to it incorrectly, overlapping a joint that should have been underlapped, creating another suspect issue potentially causing things to hit the fan. Broken tabs, side is busted off, and it's perma-formed/bent where it was jimmied incorrectly.   The baffle? Unobtainum. Long since discontinued from GM, of course. Aftermarket/capa/chinese? Also unobtanium. In GM's infinite wisdom, it appears there are at least two different variations whether the Blazer is 2 or 4 door, and I can't yet tell if they shared the same part with the S-pickups. Plan B, if I can't find a viable used one, will be to create a bracket to re-assemble the critical joint I need to seal a gap with the shroud. But that will bug me, it won't be...perfect.   The water pump bolts appear to have been installed with...plumber's putty. I guess, sure, if it works...? I've found a few "backyard fixes" like that. Someone's been here before....   If I can't find someone to jam bamboo under my fingernails to fill my free time this week I think I'll install the driver's power window motor and replace the rear door speaker that's inop. I've got a genuine GM "9.5" ohm working replacement. Why GM used a non-standard resistance....nevermind. Of course they did, you can get more sound from a cheap factory amp that way.   And the saga goes on...

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...