Question about 2002 Hummer H1

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L4E80 automatic transmission in a 2000 H1 shifts suddenly from 4 to 3 gear even at higher speed of 50 mph as soon as there is the slightest slope of some 3 or 5 Degrees. Even at 3000 rpm and up and will continue to stay in 3rd gear unless engine ist switched of. Is that a hydraulic/transimission fluid prpblem? is that due to a clogged trans-fluid filter? Could a bad trans-fuid filter lower or increase the transmission pressure that would explain the problem? The pressure gauge shows always constant 35 psi (which should be quite normal). cheers Juergen Harms MD PhD

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Posted on Jan 02, 2017

  • 548 Answers

SOURCE: transmission

With the vehicle on level ground and the engine on, check the transmission fluid level - you need to drive the vehicle a few minutes to warm up the fluid. If the fluid is low, add some fluid slowly and then recheck it. It's easy to get too much fluid in the transmission. Have you noticed any pink stains under the vehicle after moving it from a parking space? If the fluid level is okay, then a sensor could be to blame. If the fluid on the dipstick is dark and not bright pink, it probably needs to be changed. Check the service interval in the owner's manual for the mileage/age that the fluid needs to be changes.

Posted on Dec 27, 2008

  • 35 Answers

SOURCE: My H2 2003 hard or take time to shift when running to 35+ MPH

check your tranny fluid and filter. you may have a clog some where or could be low on tranny fluid.

Posted on Jul 25, 2009

  • 315 Answers

SOURCE: Hummer H2 2003, shifting problem

Yea, hummers are notoriously unreliable. They are gas gusslers too.
I'm assuming this is an automatic?
When the transmissions computer detects any malfunctions, it will give you a check engine light, or something along those lines.
Do the normal checks such as checking the transmission fluid level as per the user manual.

For further diagnostics you'll need to take it to a mechanic. It's impossible to diagnose a problem like this without driving the car and being able to reproduce the problem.

Posted on Aug 09, 2009

  • 76 Answers

SOURCE: my check engine light is blicking and i cant go

sounds like a skip if the light flashes. your vehicle goes into a limp mode if it detects a problem to prevent further damage. this is why you cant go over a certain speed of rpm

Posted on Oct 03, 2009

  • 3489 Answers


youre going to need to take it to either a hummer dealer or a reputable and trusted transmission shop. these are general motors transmissions and do not cost a lot to rebuild. the only difference in price is whether on this year you have the 350cid gas or 6.5 na motor. wish i had better news but remember that transmission is constantly trying to move 8500lbs. service every 15- 20,000 miles. let me know if further assistance is necessary. i am certified with am general.

Posted on Dec 20, 2009

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