2006 yukon wont start. Replaced battery and

Clean the battery post's and terminals and hot wires to starter and the ends of the ground wires. Try to jump start it if it starts it may be your battery or your starter is going bad.

Could be a problem with the anti-theft system, the neutral safety switch, the key switch, or the actual starter.
Will it crank in neutral instead of park ? Do you have power at the starter posts when the key is in the start position ?
Is the security light blinking ?

Hello! Do you hear a click when the key is turned?...If no click is heard either the ignition key, the Crank relay, the starter, or the battery are suspect...Having lights and radio does not mean the battery is capable of running a starter motor......Put a meter on the battery...should read 12.5 volts...Turn key...Does voltage drop to 8 or 9 volts? Bad battery...If all is well with battery and connections to it...Check the starter fuse # 33 in the under hood fuse/relay box...If the fuse is good that click you should hear is from the Crank Relay in that box...If all of the above is OK connect your meter to the Purple wire that is connected to the starter motor...When the key is turned 12 volts must be on that wire...If there is the starter motor is defective...So, #1...Do you hear a click when key is turned...That would point at a bad starter or weak battery...#2...If you do not hear a click bad fuse #33, bad Crank Relay, bad ignition switch...#3...If fuse is good Bad Crank Relay or Ignition switch; Crank Relay is a low cost item ($10)...Replace Relay...Stop there and send a comment as to results...Guru...saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

assuming that your batetry voltage is above 12.4 volts,

this can be related to natural/safety switch/relay. if it is broken it only clicks but does not allow you to turn starter. you need to replace that relay/swtich. if there is a brake pedal related circuitry on your car, yo need to control that circuit too. same applies for clutch pedal for US orginated manual transmission equipped cars. without pushing clutch pedal it wont start.

another reason for this can be the stuck starter due to corrosion or mud on it. hit it with a mid size hammer gently few times.

Sounds more like a dead battery. The one click you hear is the starter solenoid.
Turn on your headlights and try to start if your headlights go real dim your battery is dead.
If they stay bright then it could be your starter

Make sure that the starter solenoid is being activated and getting power to the starter. All battery connections and starter motor connection must be squeaky clean since any resistance in a 12 volt system may have a serious impact on power flow to device. Ignore the radio, heater etc during startup - the car is designed to turn them off when you turn the key to start so all power goes to the starter motor only.

hi there, from my experience this sounds like a simple starter motor failure, remove the starter and test in on a bench before replacing,
any other help please ask
regards roger

Remove battery connections and clean them, or try twisting cables. The clicking is the solenoid kicking in. Your likely not getting enough power there to engage the starter. Other wise, your starter is probably bad, you can try tapping it with a hammer or what ever else you can hit it with. Don't try to kill it. If it starts after hitting it, its definitely the starter motor. Start with the connections tho.

First, make sure you can turn the engine by hand. If you can't then the starter can't turn it either. Have someone else turn the key and look for the source of the click...may be a relay. Go over the starting circuit with a volt meter. Check for power at the starter main terminal and then with the key turned to "start" check for power at the trigger terminal on the starter. Check battery voltage and check relay operation.
You have a neutral safety switch on the transmission if its an automatic and a clutch switch if it's a stick. Check them as well. Make sure battery grounding on fender and block are also clean and secure.

Did you try to replace the starter cable? is the Truck turning over or just clicking.? If it's turning over and not starting. Best guess would be one of two things. Knock sensors Located under intake manifold. they get wet and deteriorate or the fuel pump. I've replaced all three on mine. 233k still running strong...