2003 GMC Yukon Denali 6.0 new part installed , no start issue

[Cway 843]

Ive slowly been bringing 2003 Denali 6.0 back into maintenance... replaced a few parts without issues but after a water pump install the truck will now turn over but not crank. Had mech with scanner come out no codes shown to prevent start or run. Was running before the water pump install without issue other than small leak from water pump. Fuel system test fine, timing is true, spark is present, battery is brand new (figure might as well get one to be on safe side) , has almost full tank of gas, MAF has been cleaned. A new throttle body sensor, thermostat, radiator installed two weeks before water pump install..no issues at that time or after till the water pump started a leak from pressure change after new radiator. As of right now its sitting in the garage with the battery out to kill the entire system to see if a reset will do anything...while I sit here baffled as to what the issue may be.   

[Jsdirt]

I think you mean it will turn over / crank (mean the same thing) but not start? 

 

I'd be willing to bet the block ground behind the power steering pump is broken, or doesn't have continuity through it. When that particular ground is bad, the truck will have no spark.

[Cway 843]

already checked the block ground, its secure. fuel pumps been checked, and starter, and battery, no codes shown that would cause her not to run. Had a mech come out scan her and go over the work that was done as Im no mech just a girl on a budget. Mech stated everything was in working condition and I had installed parts correctly as well as after going over everything he was stumped as well as to why it wouldnt crank to run as should. 

 

Edited February 10, 2025 by Cway 843

[Jsdirt]

No spark or no fuel? It has to be missing one or the other. The mechanic should've checked for both ...

 

Rarely will codes be set for a no-start condition.

Edited February 10, 2025 by Jsdirt

[Cway 843]

Mech tested fuel system is working and there is spark. Ive been down a rabbit hole with this truck and am starting to think it has a dealer code issue maybe. Which I dont think would show on a base obd2 scanner. Something along the lines of something was tripped when new battery was put in.

 

[Jsdirt]

Don't even say the "D" word regarding a 2003 truck! Steer clear of those places (dealerships) ...

 

Yeah, cheap scanners won't show Body ("B"), ABS, or "U" codes. If you've got fuel & spark, doubtful those codes will show anything related to what's happening. If there was a communication issue you'd lose fuel, spark, or both.

 

Now when you say it's got fuel, is it spraying out of the injectors?  Is there power to the injectors? Are they being commanded open? There's a test you can do with a bi-directional scan tool and a fuel pressure gauge where you can activate each of the 8 injectors individually with the scan tool and watch for the pressure to drop on the gauge. If it drops the same amount on each injector, they're all good. Any large variations, or NO variation is bad. Means those particular ones are clogged, or completely dead. Might have to get that mechanic back and use his scan tool for that.

 

Is the airbox and air filter clean? Make sure rodents didn't move in while it was down for the repairs. That can cause a no-start. An engine needs 4 things to run: Fuel, air, compression, and TIMED ignition - it will not run without all 4. 

 

Did the wires get crossed when the battery was put in? If positive & negative got connected to the wrong battery terminals by accident, even just for a second or less, you've got a big problem on your hands. Things will be cooked. If that happened you can stop reading any further - you'll have to see how many computers went up in smoke, and / or how many fuses blew.

 

Is the fuel that's in it GOOD? As in not stale, or ethanol-separated with water at the bottom? The way I test that is to grab a sample out of the schrader valve where you connect a pressure gauge. If your gauge has a bleed button just hold it in while someone turns the ignition on (WITHOUT cranking the engine) - aim the hose into a container. Once you have a little bit, see if it smells like good gas. Pour a little on a hard surface somewhere away from the work area and see if it will ignite. That'll tell you if the fuel is good or not. If it won't burn, you've found the issue. If you can see beads of water at the bottom, or lots of water, that's also a problem.

 

One more thing ... Does the engine sound normal when cranking, or does it sound like it's skipping or varying speed up and down? I'm thinking you might have either a broken or jumped timing chain if the fuel is good. If the cranking sound sounds different than it did before, and doesn't sound like it's cranking at an even, steady speed, then that means there is low compression in 1 or more cylinders. That would need to be investigated. 

 

If all the above checks out, you're going to need to hook up a more capable scan tool and make sure the MAF isn't dead or shorted. 

 

Since you have fuel and spark it doesn't sound like anything got disturbed during the job, unless somehow you knocked a large vacuum hose off, like to the brake booster ... but that's nowhere near the water pump. The no start might just be coincidental.

 

I've got burned by that situation in the past, where I was convinced recent work was to blame ... but it just happened that the ignition module failed on the truck I was working on just as I installed a new distributor. What a rabbit hole THAT was!!! Thought I had it timed wrong, and kept second guessing everything I did. Out of frustration I started testing everything in the ignition system and found a bad module.

 

One more test you can do to rule out a stopped up exhaust is take out just one spark plug, ground that plug wire away from the open plug hole to prevent over-stressing the coil, then try to start it. If it starts up and runs ( it will be loud ), then you've got a completely plugged up exhaust.

 

That's all I've got for now. Good luck! 

[Cway 843]

I thank you. As I read through everything you wrote I also went through my checklist. And everything has been checked, and rechecked. Though Ive yet to figure it out. She was running fine before the new water pump was put on. Drove her home from picking up the water pump. Pulled her into the garage and changed out only the water pump and thermostat. I was careful in doing the work cause Ive had to hold the flashlight for my Dad lol. I even stopped on my way home to do the work and put more gas in so she wouldnt be low on fuel. After the work was done I went through the normal about to drive process. She sat while I was cleaning up then I went outside and tried to crank the truck....and that brings me to how things are now. Battery is new, checked it. MAF was cleaned. Spark plugs checked, though a month ago she had new plugs and wires put on. Crank, knock, and O2 sensors were checked and made sure secure, new throttle sensor was installed with the plugs and wires but checked that too. She has a strong crank going, timing has been checked and is true. Starter was checked and is working as should. Block ground was checked and snugged up tight and not damage. I feel like its going to be something small or stupid that is blocking her from running. Had a friend come out this morning with a better scanner and no codes were thrown. On their scanner it showed Dealership Locked, was told that means they cant see the info passed that lock. Was also told that the security system might have been tripped and has blocked the truck from starting. Mech told me to have her roll backed to the dealership. But where I live thats over an hour away, down a mountain,and there are no car rentals around my area so Im fubarred at this point.

[KARNUT]

1 minute ago, Cway 843 said:

I thank you. As I read through everything you wrote I also went through my checklist. And everything has been checked, and rechecked. Though Ive yet to figure it out. She was running fine before the new water pump was put on. Drove her home from picking up the water pump. Pulled her into the garage and changed out only the water pump and thermostat. I was careful in doing the work cause Ive had to hold the flashlight for my Dad lol. I even stopped on my way home to do the work and put more gas in so she wouldnt be low on fuel. After the work was done I went through the normal about to drive process. She sat while I was cleaning up then I went outside and tried to crank the truck....and that brings me to how things are now. Battery is new, checked it. MAF was cleaned. Spark plugs checked, though a month ago she had new plugs and wires put on. Crank, knock, and O2 sensors were checked and made sure secure, new throttle sensor was installed with the plugs and wires but checked that too. She has a strong crank going, timing has been checked and is true. Starter was checked and is working as should. Block ground was checked and snugged up tight and not damage. I feel like its going to be something small or stupid that is blocking her from running. Had a friend come out this morning with a better scanner and no codes were thrown. On their scanner it showed Dealership Locked, was told that means they cant see the info passed that lock. Was also told that the security system might have been tripped and has blocked the truck from starting. Mech told me to have her roll backed to the dealership. But where I live thats over an hour away, down a mountain,and there are no car rentals around my area so Im fubarred at this point.

Vehicle manufacturers are probably going the route of John Deer. I can picture a camera on you as soon as you do anything more than add fluids. Boom shut down. Weird I know. Then explain to me how my phone always seems to know where I going? Always ready with instructions on directions. I try to explain to it I’m married that job is taken. 

[newdude]

18 minutes ago, Cway 843 said:

I thank you. As I read through everything you wrote I also went through my checklist. And everything has been checked, and rechecked. Though Ive yet to figure it out. She was running fine before the new water pump was put on. Drove her home from picking up the water pump. Pulled her into the garage and changed out only the water pump and thermostat. I was careful in doing the work cause Ive had to hold the flashlight for my Dad lol. I even stopped on my way home to do the work and put more gas in so she wouldnt be low on fuel. After the work was done I went through the normal about to drive process. She sat while I was cleaning up then I went outside and tried to crank the truck....and that brings me to how things are now. Battery is new, checked it. MAF was cleaned. Spark plugs checked, though a month ago she had new plugs and wires put on. Crank, knock, and O2 sensors were checked and made sure secure, new throttle sensor was installed with the plugs and wires but checked that too. She has a strong crank going, timing has been checked and is true. Starter was checked and is working as should. Block ground was checked and snugged up tight and not damage. I feel like its going to be something small or stupid that is blocking her from running. Had a friend come out this morning with a better scanner and no codes were thrown. On their scanner it showed Dealership Locked, was told that means they cant see the info passed that lock. Was also told that the security system might have been tripped and has blocked the truck from starting. Mech told me to have her roll backed to the dealership. But where I live thats over an hour away, down a mountain,and there are no car rentals around my area so Im fubarred at this point.

 

 

I have used many non factory code readers and scan tools and have never seen or heard of one saying "dealership locked".  That makes no sense.  

 

When you did the water pump, what did you remove/unhook to do that job?  Obviously the belt, the water pump, but what else was removed to get to that point?  

[Cway 843]

Oh yea I know about the gps / kill switch that had been a thing with manufacturers... Which has me mad and have had the truck checked to make sure she didnt have the OBDII piggyback on her. But since I work on building gaming pcs I know how a company likes to weave their own backdoors into a computer. Which has me like... yea dealership lock means come in spend 500$ while we have your truck on the scan tool long enough to clear the dealership lock code... about 5 mins. My thing is this truck as had work on her since the year after she was made without issue. (Family passed on truck that was being built out to be a sleeper) Without issue till now. I wish my Brother was still around he was the mech and knew this truck inside and out. 

 

[Cway 843]

when putting on the new water pump on I removed the radiator to get into the area to work, released the tensioner, removed the belts, removed fan using tool kit not a hammer and pounding around like some told me to do. Checking and double checking as I went on everything I was doing by the work spec pages I had. I even had cardboard laid out with labeling for each part, where it goes, etc. After I was done I went over everything checking one more time. Left her sitting after the work was done long enough for me to go in the house clean up and change clothes. Went back out checked things again.. battery, for leaks and such. Put the key in and turned it everything came on as normal before starting... dash cluster read as normal, security system acted normal, dings and beeps normal. Turned key and she gave a strong crank but never completed start. Tried again with flood mode start thinking I might have done something to flood the motor. Same things strong turn over no crank/start. Im waiting for a call back from the dealership atm..ugh

  

[Cway 843]

update... just got off the phone with the dealership and was told she has to be brought in , the dealership lock code that popped up means the security system has been tripped causing the truck not to start and would have to be ran on their scanner and reprogramed from that point. Not sure if thats smoke being blown up my arse or not. But thats the update 

[Jsdirt]

You missed my post a few back - DO NOT GO TO A DEALERSHIP WITH A 2003 MODEL YEAR VEHICLE!!! You will lose LOTS of money - trust me on that one. I've been in this game a LONG time!

 

Any shop has the capability of fixing your truck. There is ABSOLUTELY ZERO REASON to go to a dealer.

 

If you've got money to burn, then have at it. But if you're like the rest of us that work too hard for every nickel you have, then I HIGHLY RECOMMEND calling a mom and pop shop.

[newdude]

3 hours ago, Cway 843 said:

update... just got off the phone with the dealership and was told she has to be brought in , the dealership lock code that popped up means the security system has been tripped causing the truck not to start and would have to be ran on their scanner and reprogramed from that point. Not sure if thats smoke being blown up my arse or not. But thats the update 

 

 

What was the code number?

[Cway 843]

Last update... Sent the truck to the dealership via rollback. It was placed on the dealership scanner and the dealership code was cleared. Which was security system related.. took about 15 mins all together after she was off the rollback. Wasn't charged for the scan or code clearing.  Only expense was the tow truck at $250 and topping off the tank on the way home.

(Reason for the code... a bypass on the security system for the aftermarket radio. Which when upgrading the battery to the size that was suppose to be in the truck when inherited it didnt have the right one and a weak crank then, the right size and the bypass caused the dealership code from the security system thinking the truck had been stolen and the onstar killed the truck and set the code as well as popped a fuse. Needless to say the radio was off on the way home, and will be picking up what is needed so that dosent happen again. Also didnt know it had onstar running throughout the truck. But Im a girl trying.)

Edited February 11, 2025 by Cway 843