i have a 2000 gmc sierra and it is stuck in limp mode, also the message center reads 'security' all of the time. last month the transmission was replaced (because of the same issue i am having now) and it ran fine for a few days but now its in limp mode again- when i start the truck usually the gauges all go to zero, no spedo, to tach, oil etc. every once in a while when i start the truck it goes through the gears like nothing was ever wrong. i have tried turning the key to the start position and pressing the gas pedal 3 times in under 5 seconds with no results. i took it to a parts store and the code reader came up with nothing. every one i have talked to about this is completely stumped, any help would be greatly appreciated.
limp mode and limp brain
- Thread starter hank2d2
- Start date
Molson02536
New member
It sounds like your Ignition lock needs to be replace, the ignition lock on your Sierra is a multi electronic switch that controls power to the BCM (Body Control Module), ECM (Electronic Control Module), and TCM (Transmission Control Module).
When the ignition switch starts to go bad, the connection in the switch become faulty and the proper voltage is interrupted when vibration runs through out the truck. This will cause partial failure throughout your Sierra such as your transmission and your Security light being on and other abnormal things to happen.
First is to inspect the wire harness to your ignition switch to determine it's not the harness that needs to be replaced. Once that has been determined, test the ignition switch from the harness with a multi meter to see if there are any shorts or not readings when there should be.
Good luck and keep me posted, be glad to help you get your Sierra running 100% again soon.
