2007 Tahoe LT Battery Good But No Start

[rnorman4]

This is the 2nd time I got out of bed and the Tahoe wouldn't start. Last time the battery was dead so I charged it, then it started. This time most things work, headlights, radio, dash lights, power seats and windows. What doesn't work is the powerlocks, dome lights, wipers, makup-mirror-lights, battery gauge on dash shows zero and ofcourse starter. Can anyone point me in the right direction? I tried to jump start it, would not start. Perhaps one of those big grey fuses under the hood with the 4 pins on them are gone? If so how would I check those with a meter? I heard there's supposed to be a super fuse on the firewall somewhere? Could that be it?

Thanks!!!!

 

["EO" hat]

i would def try to test the alternator

- charge the battery like you did before and start the engine

-disconnect the negative terminal on the battery.

-if the engine continues to run after you've disconnected the battery, your alt is fine.

-if the engine dies after disconnecting the terminal cable, remove the alt and take it to your local parts house to test/replace

also, i would assume that any car or truck you try to jump start your 'hoe with must produce a comparable number of cranking amps (or w/e) to turn that starter. maybe not, though. i am, of course going out on an limb with this last assumption; i'm no expert

 

[rnorman4]

Still no go on the hoe.

Engine does not crank over at all. The battery is fully charged, headlights are bright, locks don't work. The run/crank relay is engaged and I have power on the run/crank bus.

Starter relay is not receiving signal to close/start when key is turned to start position.

When I turn the ignition key to the on/run position, the following messages are displayed:
Traction Control Off
Stabilitrac Off
Service 4 wheel drive.
If I put the truck in gear, there's no line under the gear position (PRND321) to indicate which gear it's in.

The drive train relay is on.

I'm sure one of the computers (ECM/BCM...)is probably not receiving one of the signals it needs from somewhere (possibly tranny) telling it not to let the truck start.

I know the starter is working because i jumped the relay and cranked the engine over - of course it would not start.

Any ideas?
Thanks,
Richard

 

[rnorman4]

BCM Fried apparently...

As suspected, a $1000+ repair. It took the technician 3 hours at $115/hour to find that the BCM (body control module) was not communicating with the rest of the truck - so they say. The BCM is $400, and they'll tack on another hour or so to put it in + tax on all that, at least a grand. What a s*%t show. I told the dealer that it's rediculous to charge almost $400 just to find the problem, he agreed, and asked would I be paying by cash or credit. The new BCM is not in stock until tomorrow, I'll go get it then and pay the final bill/face the music. I have a power train warranty on this 2007 Tahoe with 136,000kms, but apparently it doesn't cover this BCM. I can only hope the BCM is the actual problem... I'll let you know the final damages on this...

Does anyone know where to get the wiring diagram that would show the BCM with all it's inputs/outputs and connectors? I find most schematics just deal with separate parts of the vehicle with wires labeled as going to or from the BCM/ECM which makes it hard to tie it all together?

 

[bad-zr1]

$303 part at dealer in Owosso. Mi. but it did fix my exact problem. Never could find any schematics for the BCM.

 

[rnorman4]

Code U0140 BCM no comms

The bill says: U0140 code set, no comms with BCM. I attached the technicians troubleshooting etc... if anyone's interested.

I plugged in my small tester before bringing the Hoe to the garage (innova 3100) and it didn't show any DTC's in the computer. Is this normal? Should that little scanner pickup that code?

I got the truck back (they tried to charge me $1300 but I threw a fit like a b**ch and told them I was going to loose it on the service manager when I came in so they knocked off several hours of service and dropped the price of the new BCM back to $380 so I got charged $730 which is still wayyy too much in my opinion). Apparently it took over 3 hours just to find the problem, and I'm not sure how many more to fix it, even though the U0140 code is stated on the receipt.

In any case I just bought a used Pontiac Vibe today in case the Hoe decides to die again for no reason. Got the vibe cheap because it's badged GM, but I understand most of the guts are Toyota thankfully, (which is the angle the sales guy was using to get the most $$ for it).

Thanks

 

[bad-zr1]

I used an Acutron 9175 scanner and it showed no codes as well. I think most of the scanners are only set up to read ECM codes. If the check engine light is not on they are useless. A scan tool that can check other systems (body, abs etc.) is what we need.

 

[rnorman4]

I think so too. I checked into a Tech2 analizer which is running about $2k...any other options that you know of? Surely someone knows how to connect a laptop to the vehicle through some sort of black-box available from china... and get the same information as a tech2....

 

[Onatebuawer]

Very good and*informative*exchange*..*Thank you!
dubli