I have posted this on GM specific sites, but haven't gotten a response so I wanted to see if the geniuses of TexAgs knew.

I have a 2009 Silverado Crew Cab and need to tap into a 12V power source that is only active when the truck is running. These sources will not work:

cigarette light - always on
highlight/taillights - turns on when truck is unlocked via remote

This is for a relay to an aftermarket reverse sensor. Trying to only have the sensors "beep" when the truck is running and in reverse, not when I unlock it and all the lights are on or when I turn it off and the lights stay on.

TIA

MBEC -- Mid-Bussed Electrical Connector
The MBEC is located below the instrument panel to the left of the brake pedal (#4 in the graphic points to the MBEC).

MBEC Location:




The MBEC has 10 positions for connecting electrical connectors. One of these positions is designated for aftermarket utilization. Install a connector (P/N 20791502) into the open position identified in the following graphic.

Within this connector, there is a fused 30 Amp battery feed, a fused 15 Amp battery feed, a fused 10 Amp Run/Crank feed, a 300 milliamp RAP (Retained Accessory Power) feed and a ground.

Location of Connector for Aftermarket Utilization:




Important: Connector P/N 20791502 comes with a one wire lead installed. This lead will need to be removed before the connector is pinned for use with aftermarket electrical devices.

The pin out of the connector is as follows:

Cavity
Circuit Description
Circuit Number
Fuse Size

1
Ground
1050
NA

2
Battery Feed
4540
15 Amps

3
Not Used
--
--

4
Not Used
--
--

5
Battery Feed
2340
30 Amps

6
Not Used
--
--

7
Run/Crank Feed
739
10 Amps

8
RAP Feed
43
300 milliamps

Sorry, none of the graphics attached with my copy n paste. This is straight out of GM. Where are you located?

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#PIT4423D: Aftermarket Back Up Alarm Sounds When Using RKE To Unlock Doors - keywords back back-up entry keyless lamp light lighting lock perimeter remote reverse up - (Nov 13, 2009)


Subject: Aftermarket Back Up Alarm Sounds When Using RKE to Unlock Doors


Models: 2008-2010 Chevrolet Express

2007-2010 Chevrolet Silverado

2008-2010 GMC Savana

2007-2010 GMC Sierra




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This PI was superseded to update model years. Please discard PIT4423C.


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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
The below procedure is not covered under warranty, due to the concern is caused by aftermarket/add-on equipment.

Some owners may comment that their aftermarket/add-on back up alarm will sound when unlocking the doors with the RKE remote. If the perimeter lighting is on and the ambient light sensor senses a low light condition when the RKE remote is used to unlock the doors, the reverse lights will turn on which activates the backup alarm.

Recommendation/Instructions:
To correct this concern turn off the perimeter lighting feature on vehicles with DIC controls or install an isolation relay in-line to the backup alarm per the procedure below.

Install an isolation relay, part number 12167112, in-line to the aftermarket/add-on back up alarm. Connect the relay as follows:

Cut the power feed for the backup alarm and connect one end to pin 87 of the relay.
Connect the other end to pin 30 of the relay.
Provide a ground to pin 85 of the relay.
Provide a fused 12 volt power feed, that is hot in run, to pin 86 of the relay.
This procedure is not covered under warranty, due to the concern is caused by aftermarket/add-on equipment.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Thanks fighterpilot! Great information!

Where did you find it?

Can you email me the info diagrams?
tdunavant at aggienetwork . com