chevy body control module

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cbjuray

Member - Posts: 8

Joined: February 08, 2007

Location: United States

Posted: March 01, 2007 at 3:16 PM / IP Logged

I am installing an alarm in a 2007 Chevrolet Express.

Everything has checked out so far with exception of door trigger circuit. Audiovox wiring sheet shows all door trigger to be dark blue/white at pin B9, light blue connector at the BCM.

I checked the voltage at the pin, to ground, and read 12V. positive at all times. It does not change when doors are opened or closed.

My question is how can alarm trigger with no changes in voltage or continuity?

Also should I abandon the BCM connection and wire directly to all door switches?

Any help will be appreciated.

Twelvoltz

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Joined: March 24, 2005

Location: New Jersey, United States

Posted: March 01, 2007 at 3:25 PM / IP Logged

The polarity of that wire must change for the alarm to realize it is triggered. The best way to wire in an alarm is to go to each door trigger and diode isolate the connections. You can use the all door trigger but keep in mind that if the fuse blows that supplies the dome light the alarm will not trigger. Did you wait for the dome light to extinguish when you were probing that wire?

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cbjuray

Member - Posts: 8

Joined: February 08, 2007

Location: United States

Posted: March 01, 2007 at 4:20 PM / IP Logged

Thanks for replying Twelvoltz.

When I was testing with the dvm, the dome light was turned off at the dash switch so it was disabled. Does the all door trigger work from the dome light? If so can I run the trigger to the light rather than the BCM?. It will be more work to run from the door switches and diode them together , but if it's more reliable that may be the best approach.

f150fan

Copper - Posts: 95

Joined: October 28, 2006

Location: Ohio, United States

Posted: March 02, 2007 at 8:09 AM / IP Logged

I just did 2 of these vans about a month ago. You need to grab 3 wires from the lt blue plug at the bcm. They are negative trigger. Tan in b4 should be for the drivers door, lt green in a5 should be the passenger and rear cargo door, and yellow/black in a10 should be the side door. You will need to diode isolate. This van has a dome overide on the dash so if you hook into the dome and someone presses the overide switch the doors would not be monitered, so the best thing to do is go to the bcm.

cbjuray

Member - Posts: 8

Joined: February 08, 2007

Location: United States

Posted: March 03, 2007 at 1:07 PM / IP Logged

Thanks f150fan for your reply.

I did exactly as you stated. Those leads you mentioned read 0V. when door open and 12V. positive with door closed. I installed diodes on all 3 and tied them together at positive door trigger at the brain. Have not tested it yet but should be fine. Thanks much for your help.

f150fan

Copper - Posts: 95

Joined: October 28, 2006

Location: Ohio, United States

Posted: March 03, 2007 at 2:30 PM / IP Logged

Those wires should be negative trigger. They need to go to the negative trigger on your alarm brain. How did you have your meter hooked up when you tested the wires?

cbjuray

Member - Posts: 8

Joined: February 08, 2007

Location: United States

Posted: March 05, 2007 at 9:58 PM / IP Logged

The meter is a Fluke dmm. the red lead was connected to the lead coming from door switch and black lead to ground. Also connected diodes with marking band (cathode?) with band toward brain. I have something screwed up because it chirps 4 times when arming and alarm is flakey.

Disconnected door trigger leads from violet (+ door trigger input) at brain and it arms normally but of course the doors are not protected.

Also connected alarm lead, (parking light) + to the bn/wh + at the light switch per the Audiovox wiring sheet. The lights do not flash when arming alarm.

Think I've got a mess, hope you can help!

f150fan

Copper - Posts: 95

Joined: October 28, 2006

Location: Ohio, United States

Posted: March 06, 2007 at 6:08 AM / IP Logged

The meter is a Fluke dmm. the red lead was connected to the lead coming from door switch and black lead to ground.

When the meter read 0volts with the door open, that was the trigger wire going to ground. The door triggers need to be hooked up to the negative trigger of the alarm.

As far as the lights go, the BROWN / white wire is at the bcm brown plug pin b2. It is a negative trigger. If you want to hook up at the switch look for a positive brown wire. I dont remember exactly where I grabbed this wire from when I did the two vans I did.

cbjuray

Member - Posts: 8

Joined: February 08, 2007

Location: United States

Posted: March 06, 2007 at 12:48 PM / IP Logged

Thanks for the quick response. Will change to the negative wire at the brain. That should cure the incorrect trigger. Won't be able to get to the light problem this week, will keep you posted on the progress next week. Thanks so much for your help, I'll be glad to get this working and then install shelving and the van will be ready to go to work.

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chevy body control module

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