Won't start, replaced fuel pump, still won't, Code P1626 - new owner with dead truck

Hello everyone,

I've had 5 days of happy 2003 Yukon SLT ownership but last week it wouldn't start. It wasn't throwing any codes and was giving me signs of a bad fuel pump as no fuel was coming to the Schrader and I couldn't even hear the pump trying to work. (I also checked for spark and if the relays were good - that checked out). I went ahead and replaced the pump. STILL won't start up. I had my friend plug in a scanner just in case and sure enough, it threw a P1626 code, which thru some research is something dealing with antitheft and cutting fuel. Does anyone have experience with this?

I tried a reset procedure involving turning the key to the ON position for 10 mins, then off for a few seconds, and cycled that 3 times. I then started it up and it idled for 20 seconds and killed itself.

Some people have said the ignition switch, lock housing and cylinder need replaced. If it does, I would still need to bring it to a dealer to code everything and all that?

My apologies if I'm repeating any threads but I'm brand new to ownership and this is giving me quite the headache, and I've attempted to research and diagnosis as much as my knowledge base can handle.

Thank you for any advice you may be able to provide,


- Matt

Have you checked if you have a security fuse? When this happens to me, I blew my 2amp fuse. Not sure if your year had it but it may help you go in the rIght direction

sumo said:

Have you checked if you have a security fuse? When this happens to me, I blew my 2amp fuse. Not sure if your year had it but it may help you go in the rIght direction

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I tried to check that but could not locate it. Another post alluded to it being connected with the radio fuse. Pulled it and it was fine. Even tried to start it when it was out; wouldn't start.

I may have to suck it up and leave it to the dealership. It's $140 to use their Tech 2 scanner.

Try checking all your fuses before taking it to a dealer. A $140 fuse would be ridiculous. If it's security it will start and then die.

Bypass the passkey system and be done with it. 10 minutes on google and you'll learn exactly how to do it. Done it about 30 times now...and the worst side effect is the security light will stay on or flash...but the truck starts everytime.

Z28TWITCH said:

Bypass the passkey system and be done with it. 10 minutes on google and you'll learn exactly how to do it. Done it about 30 times now...and the worst side effect is the security light will stay on or flash...but the truck starts everytime.

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Thank you for the suggestion! I am currently searching for the procedures to do this. Would it be ok to run them by you once I find them to ensure they're the same as what you've done in the past?

Appreciate the consideration

1k resistor between yellow and black wires coming from the keysense

Thank you all.. I've just had a compilation of bad luck in every facet of life lately haha but this damn antitheft was the last straw. I sure hope this works. I look forward to posting my success.

Appreciate everyone's input!

YukonandtheHOE said:

1k resistor between yellow and black wires coming from the keysense

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Worked perfectly! Runs like a clock now. Radioshack didn't have anything above a 1/2 Watt 680. But it's enough.

Now I can finally enjoy it and work on some creature comforts and looks.

Thanks again!

Is there an RPO code to tell me if I have the passkey system?