4L80E Transmission problem

demented · January 11, 2007

Got a problem or so I think I do. I have a 2006 2500 hd with the 6.0 liter.My problem is that sometimes when I come to a complete stop, then go to take off the transmission feels like it slips in first gear. But because I notice it I back off the throttle and then go again it acts as if nothing has happened and its back to normal. It has no set pattern either. It has done it to me about 5 times now in 17000 miles that I have on the truck. Almost seems like it actually starts in second or third gear. Any ideas? IS there A problem with these trannies that GM knows about. If it happened frequently it would be back to the dealer but it doesn't. Almost feels like it is spinning gently on ice. I would like to have some suggestions so I know whether or not to bring it to the dealer?

ChevyTech007 · January 12, 2007

Take it to the dealer. There could be a re-flash but I don't think there is on a 4l80. There is on a 4l60. Could be an ignition switch.

Subject: MIL On, Transmission Stuck in Second or Third Gear, IPC Inoperative, DTCs P0740,P0753,P0758,P0785,P0787,P0973,P0976,P1860,P2761,P2764 and/or P2769 Set (Verify and Repair Source of Voltage Loss #01-07-30-002E - (09/23/2005)

Models: 2006 and Prior GM Passenger Cars and Light Duty Trucks

2005-2006 HUMMER H2

2006 HUMMER H3

2005-2006 Saab 9-7X

with 4L60-E, 4L65-E, 4L80-E or 4L85-E Automatic Transmission (RPOs M30, M32, M33, MT1, MN8)

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This bulletin is being revised to update model years, add additional models and add additional diagnostic information. Please discard Corporate Bulletin Number 01-07-30-002D (Section 07 -- Transmission/Transaxle).

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Condition

Some customers may comment on one or more of the following conditions:

• The Malfunction Indicator Lamp (MIL) is ON.

• The transmission is defaulted to second gear (4L80/85-E).

• The transmission is defaulted to third gear (4L60/65-E).

• The instrument cluster is inoperative.

Upon investigation, one or all of the diagnostic trouble codes (DTCs) P0740, P0753, P0758, P0785, P0787, P0973, P0976, P1860, P2761, P2764 and P2769 may be set depending on the vehicle.

Cause

The most likely cause of this condition may be a loss of voltage to the transmission solenoid power supply circuit.

This condition may also be the result of an incorrect installation of an aftermarket electronic device such as a remote starter or alarm system.

Correction

Important: If the vehicle is equipped with an aftermarket electronic device and the DTCs are being set when the device is being used, verify that the appropriate fuse is being supplied battery voltage during operation. If voltage is not present at this fuse, these DTCs will be set due to lack of voltage at the solenoids. This condition is most likely to occur with an incorrectly installed remote starting system. If this is the case, refer the customer to the installer of the system for corrections. ANY REPAIRS DUE TO AFTERMARKET INSTALLATION OF ACCESSORIES IS A NON-WARRANTABLE ITEM.

With the ignition switch in the RUN position, test for battery voltage at the circuit fuse in the transmission solenoid power supply circuit. Refer to the appropriate SI Document for the transmission solenoid power supply circuit information.

If battery voltage is present at the fuse, inspect the ignition voltage circuit between the fuse and the transmission for possible opens.

If battery voltage is not present at the fuse, test for continuity between the fuse and the ignition switch. If NO continuity is between the fuse and the ignition switch, repair the open in that circuit.

If you have continuity between the fuse and the ignition switch, the most likely cause is the ignition switch. Replace the ignition switch using the appropriate Ignition Switch Replacement procedure in SI. Refer to group number 2.188 of the parts catalog for part description and usage of the ignition switch.

icecoldtexan · January 12, 2007

Got a problem or so I think I do. I have a 2006 2500 hd with the 6.0 liter.My problem is that sometimes when I come to a complete stop, then go to take off the transmission feels like it slips in first gear. But because I notice it I back off the throttle and then go again it acts as if nothing has happened and its back to normal. It has no set pattern either. It has done it to me about 5 times now in 17000 miles that I have on the truck. Almost seems like it actually starts in second or third gear. Any ideas? IS there A problem with these trannies that GM knows about. If it happened frequently it would be back to the dealer but it doesn't. Almost feels like it is spinning gently on ice. I would like to have some suggestions so I know whether or not to bring it to the dealer?

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My '01 2500HD 6.0 with 4L80E transmission does it. It's got 120,234 miles on it now with no major problems. My '05 chevy work van also does it, makes me think it's the nature of the beast.

HDGMC · January 11, 2007

Hey I have a 2005 CC GMC 2500HD that has had the exact same thing happen. It has happened about 6 times in 15000 miles but its so intermitent that I feel it would be a waste of time taking it to the dealer. If anybody has any answers or ideas I would appreciate it.