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Ask Gm Tech (Cam) Your Own Question
Gm Tech (Cam)
Gm Tech (Cam), Cadillac Mechanic
Category: Cadillac
Satisfied Customers: 29534
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Hows it going. i have a 2007 escalade and the headlight will

Customer Question

hows it going. i have a 2007 escalade and the headlight will not turn off. eEven with the vehical off. I have changed the relay, dimmer switch, headlight switch, and ambient light sensor. THEY STAY ON...... Im thinking this is a pcm issue. plzz help
Submitted: 2 years ago.
Category: Cadillac
Expert:  Gm Tech (Cam) replied 2 years ago.

Hello there, I am Cam. Can I get your first name please? I do agree its a module, but not the Powertrain Control Module (PCM), rather I am thinking the Body Control Module (BCM). Can you tell me if you can cycle high to low beams when they remain on?

Customer: replied 2 years ago.
Sorry its Clayton. They stay with the highs. I can unplug all the sensors I listed above and they stay on. Only way to kill them is to pull the relay. If I disconnect the battery and reset the mods, it will randomly turn back on. Randomly meaning instantly or a few minutes later.
Expert:  Gm Tech (Cam) replied 2 years ago.

Clayton, that last bit is good information. I would like you to check a couple things before we go too far then. Can you see if there is any water intrusion, corrosion into or under the fuse block under the hood. See if any of the terminals have corrosion. If no then under the dash, left side under the steering wheel is the Body Control Module (BCM), its a thin tall module with several connectors about 1" x1", see if any are chaffing. If not then try tapping sharply on the housing of the Body Control Module (BCM) and see if that makes a difference. If no then I am thinking it is your Body Control Module (BCM) that has failed.
And if tapping sharply on the Body Control Module (BCM) does change it, confirm wiring and connections and replace it anyway then .

Customer: replied 2 years ago.
Does the bcm control your a/c door actuators also. The same day my driver side started to only blow hot. I know it could be a number of other factors I'm just ask since they both started at the same time.
Expert:  Gm Tech (Cam) replied 2 years ago.

No, the actuator would control the doors and specifically the actuator for the drivers side.

It is located under the dash, passengers side just right of centre over the transmission hump.

Expert:  Gm Tech (Cam) replied 2 years ago.

Here are directions. These show it without the centre console, but you can get at the single screw using a deep 7mm and ratchet then get at the actuator.

Customer: replied 2 years ago.
Hey Cam. I tapped on the bcm just like you said and the lights started working again. So I think I've figured out the ac also. I looked online and it shows a recalibration procedure. I can't seem to get it to work. I pulls the 10 amp hvac ignition fuse wait 10 seconds, replace fuse, start vehicals and wait the 40 seconds but I'm not getting anything. If i put power to all the actuators and they work fine. Is there something I'm missing, am I pulling the wrong fuse?
Expert:  Gm Tech (Cam) replied 2 years ago.

try the HVAC/ECAS fuse and see.

Customer: replied 2 years ago.
Can't seem to locate that one. I see one under the hood for hvac battery
Expert:  Gm Tech (Cam) replied 2 years ago.

YEs, HVAC battery. Do that with the key off.

Customer: replied 2 years ago.
key is off. This is the steps I have.
1. Place the ignition to the off position.
2.connect all previously disconnected components.
3.remove hvac/ecas fuse for minimum 10 seconds.
4. Install fuse.
5.start vehical.
6. Wait 40 seconds for the hvac Control mod to self calibrate.
Customer: replied 2 years ago.
How will I know when it resets?
Expert:  Gm Tech (Cam) replied 2 years ago.
If it works properly after then it's reset. It takes only about 1 minute to reset.
Customer: replied 2 years ago.
I know this my sound dumb. The off position is one click foward correct?
Expert:  Gm Tech (Cam) replied 2 years ago.
For the ignition switch, yes but I like to have the key out of the cylinder for this. Then I know it's off.
Customer: replied 2 years ago.
Still nothing. Is there anything else I should try