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TrailblazerSS
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Discussion Starter #1 (Edited)
My company installs GPS tracking devices in vehicles. I have completed 25 installs into 10 2010 Lincoln TownCars, 10 2010 Cadillac DTS's, 5 Cadillac Escalades for a Limo company.

I am trying to monitor the Rear Doors and when they open it sends the signal to my tracking device which then throws a message to my server so the user on my program knows the vehicles door is open. On the Towncars it is one wire for the two rear doors so it is one splice and adding of a relay and you are good to go. With the Cadillac vehicles there is one wire for rear each door, and I wanted to monitor BOTH doors together. This requires use of dioides to prevent backflow into the BCM which could make the car think two doors are open if only one door is actually open....So I am using a 1amp diode to isolate each wire...I spliced into each door wire, put the dioide in line and then connected BOTH diodes to the one wire that feeds the relay then sends the signal to my tracking device. Out of the 15 Cadillac vehicles that were installed...2 DTS's and 1 Escalade got a fried BCM after about 7-10 days of using the vehicle and everything working properly. After 7-10 of the vehicles being used ALOT and everything working 100% including my tracking device and door sensing, the cars started having issues, headlights wouldn't turn off, blinkers didn't work, trunks wouldn't pop ETC...

THe Cadillac tech looked at my companies install and said everything looks to be installed right yada yada yada....750 in labor and parts on ONE DTS...So I cannot have this happen to anymore vehicles....Any ideas, please feel free to PM me with any questions...The door triggers on the vehicles are negative door triggers so my install looks something like this...The cathode of the diodes are FACING the BCM which should not allow backflow into the BCM, only allowing flow into my relay then tracking device...



AND here is more on dioides...

http://www.the12volt.com/diodes/diodes.asp


Please someone give me some insight...I have two installers working on these vehicles who have done alarms and other vehicle monitoring for over 5 years and I really cannot figure out why it would take 7-10 days for symptoms to appear...What do you guys think?!?:dunno:
 

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Bet you cant tell
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thats odd there is back feed if the cathode side is facing the BCM. im assuming you put diodes on all wiring to the truck.
 

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TrailblazerSS
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Discussion Starter #3
thats odd there is back feed if the cathode side is facing the BCM. im assuming you put diodes on all wiring to the truck.
the cathode is facing the BCM on the two door wires that i spliced into.

other than that i just tapped into a 12 volt constant on the vehicles, wired a ground wire to the chassis and tapped into the ign wire. i don't have the colors of the wires as I am not at my office right now...but the only wires that got diodes were the door wires....that is how my company has done these installs for years now and have done hundreds/thousands of vehicles...this one makes NO sense...
 
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