Not a critial issue at this point, just tossing this out to see how many others have run into this and if anyone has found the 100% solution. I have some ideas, but have not reserached or tried to solve problem yet as it seems to always start.
2005 GMC Yukon Denail 6.0L
Problem did not start until about year 18-19 and around 260,000 miles.
When problem started to happen, maybe 1 out of every 20-25 start attempt problem would show up, then slowly it worked its way to about every 1 in 4 start attempts.
On the first start attempt regardless if truck had been driven or not, regardless of how long truck has been stopped, often the engine will crank but not start on the first crank attempt, but engine will always start on 2nd crank attempt, often starts fine, sometimes engine will run slightly rough for the first few seconds.
I have researched a bit and nobody has seemed to find the exact problem. Some folks have replaced everything under the sun with no solution. So far the engine always starts on the 2nd crank attempt, I have not been stranded, YET. But once stranded, I may find the exact problem!
I feel about 90% sure the problem is with the key/immobilzer system. I need to get my more advanced scan tool on the truck to see if can find any clues and maybe even carry it with me to check on status when the engine does not start.
I also need to probably swap keys for a while and see what happens.
A buddie of mine actually did a immobiler bypass with a resisitor for this and seems to think if solved the problem.
One other strange behavior I noticed and have not bothered to look into is I have an UltraGauge plugged into the OBDII port and have noticed the UltraGauge does not go to sleep like it used to and should when the engine is shut down. Seems the UltraGauge stays awake for a few minutes after the engine has been shut off. I have not timed for how long, may not be related??
Anyway just thought I would see how many others have run into this issue, clearly I think you would still need your 15-20 year old truck to have this problem.
2005 GMC Yukon Denail 6.0L
Problem did not start until about year 18-19 and around 260,000 miles.
When problem started to happen, maybe 1 out of every 20-25 start attempt problem would show up, then slowly it worked its way to about every 1 in 4 start attempts.
On the first start attempt regardless if truck had been driven or not, regardless of how long truck has been stopped, often the engine will crank but not start on the first crank attempt, but engine will always start on 2nd crank attempt, often starts fine, sometimes engine will run slightly rough for the first few seconds.
I have researched a bit and nobody has seemed to find the exact problem. Some folks have replaced everything under the sun with no solution. So far the engine always starts on the 2nd crank attempt, I have not been stranded, YET. But once stranded, I may find the exact problem!
I feel about 90% sure the problem is with the key/immobilzer system. I need to get my more advanced scan tool on the truck to see if can find any clues and maybe even carry it with me to check on status when the engine does not start.
I also need to probably swap keys for a while and see what happens.
A buddie of mine actually did a immobiler bypass with a resisitor for this and seems to think if solved the problem.
One other strange behavior I noticed and have not bothered to look into is I have an UltraGauge plugged into the OBDII port and have noticed the UltraGauge does not go to sleep like it used to and should when the engine is shut down. Seems the UltraGauge stays awake for a few minutes after the engine has been shut off. I have not timed for how long, may not be related??
Anyway just thought I would see how many others have run into this issue, clearly I think you would still need your 15-20 year old truck to have this problem.
