BCM or Starter or WTF

[Granprixfan]

First of introductions I'm Carlos
I've lurked and learned a lot since we got an 03 Yukon XL
Lots of knowledge to be shared here and I appreciate the community
Now I am hopping someone can chime in here for some cyber diagnostics;

Taday driving home from work cruising around 75mph engine sputtered over three miles then cut out
Safely made it to shoulder
Would crank/start then badly idol and die in a matter of five seconds
After fifteen minutes or so she started rough but then kept rough idol long enough to put in drive.
It smoothed out and At this point I was able to drive off highway and take backroads
Stopped at ATM got cash which was wise as she died a mile down the road from bank and never restarted so towed
So to reiterate
I was going about fifty on backroad and she simply cut out
At this point she would not even crank
It was as if BCM was not recognizing the key
I tried the wife's key (yeah she was riding shotgun and added to the angst)
Again nothing, no crank, no solenoid clicking, nothing
Dash DIC displayed no messages not even saying driver 1 display with key ect

 

[Granprixfan]

So I started to diagnose starting with alarm.
Why you ask?
This was the most recent change to vehicle.
All connections soldered to UNCUT factory wire (only stripped enough plastic sheath to wrap/twist wire and solder the connection and wrap/tape/shrink wrap even zip tied over for redundant measures
All connection check out sound and more importantly I'm not wired for kill circuit just for this reason, kill power at freeway speeds is putting everyone in danger
...well I digress
The starter circuit received correct voltage when in accessory position and at start/crank key positions
This is true at both at input to alarm and at firewall
Next step I'm thinking is to check if starter getting juice
Thoughts?

 

[ezdaar]

Your infested with gremlins!

Serious note, no idea. Toss a code scanner on it and see if anything pops up.
You do have the ol' trusty bluetooth obd2 scanner and torque app..... Riigghhttt?


Yess check voltage ro starter.


Dumb question.

Did you check fuses?

 

[Granprixfan]

Thanks Doug
I really did need to lighten up and laugh!
sitting here having a triple shot and scratching my head
Definitely need to get one of these OBDII blue tooth scanner
Didn't know that they existed
Please LMK brand and if you care to share price expected to shell out
Greatly appreciated brother

Ok so going back to my belief that BCM may be the culprit;
DIC has been displaying rear left door ajar
Did I a search on this site and others and it seems to be the consensus, after following the logic of others and their diagnosis steps ...
This message started after I did an OCD detail on the interior and carpet in particular
I thought maybe I had corrosion on some connector...But none found
Interior lights stay on and need bypass button on light switch to remain depressed keeping lights from staying on.
Factory security system started to go off in middle of night w/o reason other than system/BCM/DIC reading left rear door ajar
So three weeks ago or so I posted how some low life broke in by stabbing a flat head screw driver between sheet metal and door handle and unlocking. Thief took some tools and change but no vehicle damage besides the door ( not after vehicle or stereo)
But I was naturally pissed as happened right in front of house below my bedroom window and I couldn't use factory alarm due to false alarms (can't have the thing blaring at all hours
So in a knee jerk reaction
Last week I had remote start alarm installed
Then this afternoon the truck dies while driving.
But I never wired it to "cut off"...nothing from alarm could have caused it to die whilst running
Back to the present,
After some time trying to get it started the DIC wouldn't light up
So m thinking at this point BCM isn't even recognizing the key

 

[Granprixfan]

Ok so today diagnosis ;
I was able to get to crank yukon by Jumping starter with key in ignition
So WTF
The BCM recognized the Keys

So back to the simple things;
Popped under hood fuse cover

relay for starter checks out
Started checking fuses
Found the 20 amp PCM fuse blown
Replaced and was able to crank and START

but would not stay on even then she has very rough idle
Died when shifted into R or D

Got a mechanic friend to plug scanner OBDII port
Tah-Da!
Fuel pump
Went to Napa got a Delphi Fuel Pump Assembly
PN FG0273 and DFG0273 on box
and
Also purchased a fuel filter
Napa Gold PN 3481
(My Yukon is an '03 with a 5.3 non-flex fuel)

1.5 hrs of wrenching and all back together
Took her out for a quick test drive....runs fine now

 

[Granprixfan]

Still wondering why the PCM 20 amp fuse blew

I don't have a schematic so I can only speculate;

Circuit overload from cranking?
Or
Overloaded from combination of cranking and the radar detector and wife's I pad plugged into 12v plugs
Oh and stereo on (Pandora through IPad to system)

 

[ccapehartusarmyINF.(ret)]

the ciggerette lighter were youd plug in your ipad is on the same fuse with the OBD2 port
im assuming yer fuel pump blew the PCM fuse