2008 yukon problem start with aftermarket key

[Andrewd4547]

2008 yukon denali 6
2 came with 2 keys i assume original from previous owner. I got a locksmith to make me a 3rd as a spare for almost $100 Canadian. I recall him sitting in the vehicle I assume programming it. It intermittently worked. Sometimes it would start other times alarm. If I played and unlock relock push the brake eventually the right combo would start it. Now I find myself with that as my only key. The fobs are aftermarket but never given me.an issue. It's getting very hard to start. 1 min became 2 then 5 now I feel like I can't get it to start. Does anyone know what combo of locking unlocking either with key. Key fob or door buttons will make this thing fire up? I was never sure of exactly what combo did it. Didn't care on a hot summer night. Now it's Canadian winter which should be illegal if we can figure out how to charge the atmosphere for crime against humanity.

 

[Doubeleive]

2008 yukon denali 6
2 came with 2 keys i assume original from previous owner. I got a locksmith to make me a 3rd as a spare for almost $100 Canadian. I recall him sitting in the vehicle I assume programming it. It intermittently worked. Sometimes it would start other times alarm. If I played and unlock relock push the brake eventually the right combo would start it. Now I find myself with that as my only key. The fobs are aftermarket but never given me.an issue. It's getting very hard to start. 1 min became 2 then 5 now I feel like I can't get it to start. Does anyone know what combo of locking unlocking either with key. Key fob or door buttons will make this thing fire up? I was never sure of exactly what combo did it. Didn't care on a hot summer night. Now it's Canadian winter which should be illegal if we can figure out how to charge the atmosphere for crime against humanity.

the keys for these trucks can be programmed in like 2 seconds, as long as you have 1 working key
1. insert working key, turn to run. when the security light goes out remove the key
2 within 5 seconds insert the new key turn to run, when the security light goes out remove key
3 repeat as needed for however many keys you need to program I believe these trucks will do either 4 or up to 8
they just have to be done all together as noted above, otherwise you have start over from step one for all keys.
when you do this process any old keys will no longer work unless they are again programmed as noted above.

for instance if you programmed a couple new keys and later on down the road found a older key it would not work unless you re-programmed it in the steps above all back to back.

the above process only works for 2007-2014 suv's and 2007-2013 pickups.
with the 2015-2020 k2's you need 2 working keys to program more.
and previous years pre 2007 do not use a chip key

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[Bronson357]

On my 07 it's easy get a key cut , go into the dic and you will find it, was able to cut keys and fob in roughly a minute. The 2012 was a different story,2nd fob easy key not so much,I had 2 working fobs and one working key. Had 2 keys cut had to have the dealer program them. They did it free

 

[mikez71]

Did your original keys always work?
If they were also intermittent, perhaps a problem with the antenna module around the ignition switch.

Another option, you find someone to tune vats out so you don't need a transponder key.