Hood open message. Latch and BCM replaced.

[SolApathy]

As the title says, 2007 Tahoe. Already replaced the BCM and hood latch. Body ground to Black (C) gives me 12V, Which make no sense. Just at a loss at this point. Hoping that someone has a thought. THough I would love to use remote start again, getting that message out of the DIC would be even better.

 

[mikez71]

Looks like purple wire should be grounded and pink/black not grounded to not have 'hood open' message?

 

[swathdiver]

Did you look for any BCM codes before you replaced it?

 

[SolApathy]

Turns out there was a break in the wire going into the connector to the BCM and now that error s gone. I cleared the airbag code, but now with the new BCM my rear windows do not respond at all with the driver switch or the door switches. I really don't want to swap out the BCM if it is simply something I need to reprogram.

 

[j91z28d1]

Turns out there was a break in the wire going into the connector to the BCM and now that error s gone. I cleared the airbag code, but now with the new BCM my rear windows do not respond at all with the driver switch or the door switches. I really don't want to swap out the BCM if it is simply something I need to reprogram.

did you program the new bcm to your truck, if not do you have the capability of programming it? did you replace the bcm yourself and still. have the original one?

 

[Fless]

Why not swap the BCM back to the original?

 

[ccharlton]

Any updates on this? I’m in the same exact boat as OP. 2008 Yukon… hood open message and some other weird things happening randomly. Replaced hood latch and BCM to no avail. New BCM programmed to my vin… rear windows won’t respond at all so I switched back to original BCM

 

[ReaperHWK]

People are way too quick to replace the BCM when it’s almost never the problem. Get the schematic and check all wiring point to point first.

 

[Fless]

Any updates on this? I’m in the same exact boat as OP. 2008 Yukon… hood open message and some other weird things happening randomly. Replaced hood latch and BCM to no avail. New BCM programmed to my vin… rear windows won’t respond at all so I switched back to original BCM

Unfortunately the OP hasn't been on here since July, so I wouldn't expect an answer from that direction.

Wiring diagrams at www.charm.li.

 

[Doubeleive]

if I had to guess I would guess the BCM needs to be programmed again while attached to the vehicle.
I would also scan the system and be sure the vin is correct before purchasing techline subscription

 

[j91z28d1]

if I had to guess I would guess the BCM needs to be programmed again while attached to the vehicle.
I would also scan the system and be sure the vin is correct before purchasing techline subscription

that's makes me wonder. when they say flashed for vin. is that something they do before buying them. not the same as flashing the new one using the acdelco tech line?

 

[Doubeleive]

that's makes me wonder. when they say flashed for vin. is that something they do before buying them. not the same as flashing the new one using the acdelco tech line?

It could be something as simple hex editing the vin from a compatible bcm and send it, I guess it could vary from vendor to vendor

 

[Doubeleive]

Just like I have a obd genie it works unlimited for my vin, for radios on the Silverado all it does is erase the vin and then when it re-powers up it learns the vin but nothing else changes, the previous settings are all there from the previous owner/vehicle

 

[j91z28d1]

ahh. yeah that would make since why they aren't having any luck with replacement bcm's working right.

 

[Doubeleive]

ahh. yeah that would make since why they aren't having any luck with replacement bcm's working right.

it's also why it is best to get a BCM from the exact same model and year

 

[ccharlton]

I have no voltage at neither the purple (hood closed) nor the pink/black (hood ajar) wires out at the switch wiring at the core support. However, I have roughly 10 volts at both wires at the BCM connectors (X5 #15 & X4 #17). Should I have voltage at both simultaneously? I thought it was one or the other?
BTW I should add that the ground tests good out at the latch wiring.

 

[mikez71]

yes voltage on both.

purple wire grounds when hood closed
pink/black grounds when hood open

tested wires at core support with latch switch disconnected?
If so, you must have a break or bad connection with wiring.

If you left the latch switch connected, then the switch could be grounding out the voltage.
But it should only ground one of them, so your new latch could be bad, *if* wiring checks out.

 

[kbuskill]

The way I read the wiring diagram you shouldn't have voltage at either.

The hood latch is just a simple switch that either connects the purple wire to ground with the latch/hood closed OR provides ground to the pink/black wire when hood/latch is open.

The BCM is looking for a ground signal NOT power.

 

[mikez71]

I am assuming the meter is measuring power from the BCM, because something has to ground out, for it to know it's grounded.
If you look at the diagram, it shows BATT and SBAT which I assume is battery and switched power..
Guessing it wants to know hood is latched closed before you drive off, yet needs to know if the hood is open always, for security system & remote start.

 

[kbuskill]

I am assuming the meter is measuring power from the BCM, because something has to ground out, for it to know it's grounded.
If you look at the diagram, it shows BATT and SBAT which I assume is battery and switched power..
Guessing it wants to know hood is latched closed before you drive off, yet needs to know if the hood is open always, for security system & remote start.

I see what it says but it would seem to me that if the BCM is pushing power to that switch and the switch is connecting it to ground it would be a dead short.