2006 GMC Sierra with 5.3lt 8 cyl engine 4x4. Key on, all lights warning lamps light up.Turn key to start and all warning lamps turn off.Engine not starting,Checked battery,ok.Starter was replaced two weeks ago.Checked ground,good.Checked for codes,PO654 and P0650 present. What are these codes?.

SOURCE: 1990 GMC Sierra 4x4 1500

the connections near the front axle that activate the motor to engage the system aren't melted? That's a comon problem for that body style. If there good, sounds like it could be that motor itself. To figure out if it's you motor or transfercase, jack up the rear end, have a friend inside shift into 4 wheel drive, or try to, and put it in gear and apply some gas. If the front driveshaft is turning then it's something with the front end. If not, farther back in the system.

Wade Cook

• 6 Answers
• Posted on Jan 27, 2009

SOURCE: 4X4 inop on 2003 GMC Sierra 2500HD

I have found that when you are going to engauge 4x4 high, it is best to only be going about 3 miles an hour. Not faster, not stopped. It likes some movement to help it mesh. I've had perfect shifts since I started this. Hope it helps. Wade.

SOURCE: where is the 4x4 encoder motor sensor located on my 03 sierra

the encoder motor sensor is inside the encoder motor. the encoder is located at the transfer case. Remove the encoder and by part number 88962315 this is the sensor. you will have to retime the motor after
hope this helps

Mike Butler

• 6674 Answers
• Posted on May 18, 2009

SOURCE: key is on....battery is good....engine won't turn over

Black box (plastic) usually pretty handy to battery, you should see red (usually) cable from battery running to it. Another thing that came to mind, you don't have anti-theft system on that do you? Sometimes they will cause problems after a dead battery. Try using your key & valet key to unlock the doors, manually especially drivers.

SOURCE: gas gauge not woking properly gas tank only accepts a little gas

I had the same problem. My gas gage would read full and as I drove the gage would read empty; even when I had a full tank of gas. All I had to do is buy a new gas cap... yes that is all! $15.00 and a day later the gas gage is fixed.