another 2007 tahoe no crank no start FIXED!!! FINALLY

[MrDietz]

Hello everyone . I am new to the forum so just wanted to say hi and ask for help. please forgive me if i forget something or if i am all over the place. thanks in advance.
so i bought a 2007 ppv that had been sitting for two years. drained the fuel and and put a new battery in it and fired right up. drove it about 40 miles to get it home with no issues everything working. changed the fluids and started driving it to work. after about two weeks i was on the freeway and i lost all gauges it just went dark so i pulled to the side of the road .(truck was still running) shut the key off and checked everything out. at this point i was assuming it could have been the alternator or the battery and needed to get to work, so I got it towed home. alternator tested good from two different places and battery tested good(its brand new) and its charged. (just trying to give context sorry for the long story) the interior lights would always come on once i hooked up the battery but they were very dim. so i started basic check power and ground . the ground on the passenger side cylinder head was loose. so i tightened that up and fixed the lights from staying on . while the ground was loose before i found that it was loose.the blinkers and headlights worked but once i tighted that ground the headlights and blinkers stopped working. I am wondered if that ground being loose fried the fuse box or the bcm. none of the interior lights are working, locks don't work. can not open rear liftgate , the radio works. ac blower motor kicks on. all the warning lights pop up on dash, windows roll down and horn works. but none of the gauges/needles move at all .fuel, voltage ext.... the line under the prndl is not there ,the mileage and trip do show. all fuses are good under hood and in cab,including the main fuse that powers fuse box . i can jump the starter and it will crank just wont run, just another thing to eliminate. i did notice the power/tran and run/crank relays getting a little warm just sitting there with battery hooked up no key on. i did replace the relays with new ones and still no crank. i am going to try to ground those relays with a jumper since they do have power to them. all the stuff not working does not have power at the fuse box under hood. i have been limited on time so this weekend i am going to be able to dive in . i got my fluke and light tester out of storage and i have access to pro demand so i will be printing out the schematics for this weekend. I just wanted to post on here to get the gears turning in case i dead head while going thru it this weekend. so i can have somewhere to turn instead of scratching my head. thank you to all for any help or insight. look forward to making some new friends and talking about what mods im going to do to this hog once its running again. first mod was a lace steering wheel cover to give it that old truck feel. lol thanks again.

 

[MrDietz]

To anyone who looked at this post. I think I found the problem, after hours of going thru testing power checking grounds ,Following schematics, I was getting power in but not out. The Bcm left the chat lmao

 

[Doubeleive]

To anyone who looked at this post. I think I found the problem, after hours of going thru testing power checking grounds ,Following schematics, I was getting power in but not out. The Bcm left the chat lmao

that's rare, perhaps some wires got crossed at some point causing the chip to fry, I have seen that on other brands but not on a gm.

 

[MrDietz]

that's rare, perhaps some wires got crossed at some point causing the chip to fry, I have seen that on other brands but not on a gm.

that's what scares me about buying one for 250 from eBay and it doing the same thing. the ground being loose wouldn't have cooked it like that i don't think.

 

[mikez71]

That is weird that tightening the ground caused the headlights and blinkers to stop working..
Hopefully it was the BCM itself. Maybe another failed component on the PCB could cause this?
Circled in red, I wonder if that looks overheated..

 

[MrDietz]

so i know the bcm has to be programmed per vin, i get that but just wondering if i got one from a junk yard that is same year would i be able to try it to will run my tahoe?

 

[MrDietz]

That is weird that tightening the ground caused the headlights and blinkers to stop working..
Hopefully it was the BCM itself. Maybe another failed component on the PCB could cause this?
Circled in red, I wonder if that looks overheated..
View attachment 464455

that was the first thing i saw yesterday , hopefully that failed and caused the mess .

 

[MrDietz]

ok guys so i ordered the bcm from ebay that will come programmed to my vin. should be in next week. i will keep you guys posted , everyone cross your fingers and toes for me .

 

[MrDietz]

So I’m still waiting on bcm, but it was bugging me to find out what killed it. So today I went out and started looking over stuff again and look what I found. There was like two strands on each wire barely holding on .I’m glad because it would have sucked to have put new bcm in and it fry again. I also put a new/used fuse box in and got rid of that stud and put a regular 10mm bolt and solder the wires.

 

[Fless]

Was it rubbing on something, or rodent damage?

 

[mikez71]

He said it was a stud that he replaced with a bolt.

Just looked at mine, what you were missing is a wire loom holder that sits right on top of that stud.
(small plastic standoff with a ziptie)

 

[guy from norcal]

Good catch on those wires. Hope the new ecm fixes it

 

[MrDietz]

Was it rubbing on something, or rodent damage?

it was rubbing on a stud

 

[MrDietz]

He said it was a stud that he replaced with a bolt.

Just looked at mine, what you were missing is a wire loom holder that sits right on top of that stud.
(small plastic standoff with a ziptie)

View attachment 464941

my wife has a 2013 and yeah it has that part ziptie that sits on stud. once i get the new bcm and it runs im going to go thru and replace loom and tape and those stand offs

 

[MrDietz]

so i was supposed to get the bcm on the 14th but i did not. i contacted the ebay seller and it looks like ups lost the package . they said if i have not recivied it by 8/19 request a refund and it was there last bcm thru that seller. fml so i will order one thru another seller and hope for the best.

 

[Doubeleive]

yep, you have look at all of the engine compartment wires and adjust them as needed over time they sag or the clips break, etc
everyone should do this as general preventative maintenance.
some of those stand offs are not sold separate by gm and only come with a new wire harness, so the junkyard is your friend
a small flat head screw driver or pick tool allows you to open them and then move them to your wire harness
when you are looking under the hood anytime, just eye ball everything and if it looks questionable adjust as needed.
you can use zipties or electrical tape to support wires if clips are not handy
anything that sits on top of the engine or crosses over it is critical.
anything that just dangles free should not be, just wiggling up/down over time the wire inside can break where there is a bend (invisible break)

 

[Doubeleive]

so i was supposed to get the bcm on the 14th but i did not. i contacted the ebay seller and it looks like ups lost the package . they said if i have not recivied it by 8/19 request a refund and it was there last bcm thru that seller. fml so i will order one thru another seller and hope for the best.

if you find a matching vehicle at the junkyard, the dealer or a good shop can program it. typical cost is $118-180.00 for programming
if you have the right tool/interface and a windows pc you can pay the $45 techline fee and program it yourself.
but unless you are already invested in a tool like that and it's only going to be a one time thing, then it's cheaper to just have it programmed.

 

[MrDietz]

if you find a matching vehicle at the junkyard, the dealer or a good shop can program it. typical cost is $118-180.00 for programming
if you have the right tool/interface and a windows pc you can pay the $45 techline fee and program it yourself.
but unless you are already invested in a tool like that and it's only going to be a one time thing, then it's cheaper to just have it programmed.

yeah its just easier to have one shipped programmed. i was looking at doing all that but like you said its a one time purchase. the VCX nano is about 100-120 and the 45 for techline then the bcm is another 80-250 depending on where you buy online. no junk yards here have tahoes in that year right now. although if i read right i can turn on and off features?
do you know if any bcm that year will work or does it have to have the same part number on it?
thanks

 

[Doubeleive]

yeah its just easier to have one shipped programmed. i was looking at doing all that but like you said its a one time purchase. the VCX nano is about 100-120 and the 45 for techline then the bcm is another 80-250 depending on where you buy online. no junk yards here have tahoes in that year right now. although if i read right i can turn on and off features?
do you know if any bcm that year will work or does it have to have the same part number on it?
thanks

I do not know what the crossover part numbers are and the kicker on top of that is often when you pull one from a yard the darn thing may not even have a label on it, so the best bet is to always get one from a same year/make/model.
as far as turning options on/off that's not going to happen without special software or a 3rd party programmer, when it is programmed via the vin it set's it all based on the vin number of the vehicle, you "might" be able to add something like say power running boards if it allows it to be checkmarked in techline. options are pretty limited.
it's a safety issue mostly, if they allowed things to be edited and someone added something incorrect or removed something it could cause damage or a accident

 

[MrDietz]

ok so a little update for those who care. i got my refund and ordered another one from a different company preprogrammed to vin. fingers crossed. should be here next week, i will keep you guys posted. i have not wanted to touch it since it broke down but i think once its running again i will go thru is and fix a lot of the stuff it needs, like carpet ,dash and pull the rest of the wiring for the antennas and plug some holes. thanks again for all the help and feedback.