2004 Yukon Vehicle Anti Theft System Function

[Gizmo2K2]

Hello all. I'm a newbie to this forum. I'm here because I am trying to help my brother's neighbor who lives across the street from him. The neighbor, "Tim" owns a 2004 Yukon. The vehicle has been sitting in his driveway for months. I struck up a conversation with him a few days ago and he told me that the vehicle won't start and when it does, it sometimes takes 20 minutes to get it going. I wasn't sure exactly what he was talking about so I asked him to turn the ignition to start so I could see and hear firsthand what the truck is doing (or not doing). Upon starting the Yukon, everything sounds normal. The fuel rails are energized, the starter is under power, the engine turns over freely and I was waiting for the engine to fire up. But after 3-4 seconds, everything shuts down. He turned the truck on again and the same sequence repeated itself. Tim told me that he waits 20+ minutes to attempt another start. Sometimes it fires up, other times it repeats the same sequence mentioned above. With the unpredictability of a successful start, it is nearly impossible for him to use the truck for his lawncare service. Tim says that this condition began "about 9 months ago", which puts us in the Fall/early Winter 2022.

Is this a function of the vehicle anti theft system?

Any help, guidance, recommendations or assistance would be greatly appreciated.

Thanks.

Bill

 

[S33k3r]

If it were the anti theft system, you should get an idiot light for it. Everything I've seen like this -- without the antitheft being the problem -- was either an aftermarket alarm with start disable, or a similar device from a auto sales & leasing company. So I'd check for wiring that isn't OEM. And, to be honest, you might also want to check some of the fuses, but which ones I don't know.