2003 Yukon Clicking when trying to start

It sounds like your battery is weak or that you have a bad battery connection. I would first clean and tighten the battery terminals and charge the battery. You may need to have the alternator tested.

Hi Full_of_Regrets, I cleaned and tightened the battery terminals and the battery was replaced about 2 months ago. It still just clicks rapidly when trying to crank and the horn is still very faint when locking/unlocking doors from the keyfob.

Dude, you have a short to ground inside the case of the starter solenoid. Replace the starter.

Check your ground wire to the pcm located on the valve cover post, rear of engine, passenger side. It will break off or be corroded real bad. Disconnect it from that point, i just ripped mine off, and crimp an extension wire to it,,and reground it to the firewall where the engine ground strap is. This fixed my electrical problems on my 2003 yukon. Theres also 2 ground wires located under driver side door, under side chassis, behind running boards, check those for corrosion too. Also, one more ground wire, front bumper drivers side, behind bumper on chassis there are 2 ground wires located there, i removed them,,and reground them to groundpoint inside engine bay with other ground wire from pcm. This WILL fix your problems, and while you are at it, upgrade your factory ground wires for altenator and battery becsuse they are crap.

my mom went to the store 2 mins away and then boom i believe the starter went out