Multiplexed Vehicles

Ok, since I am now getting back into Car audio and security (been doing other 12V stuff, like commercial GPS, Mobile Data Terminals, etc. for the last three years...) I was wondering if any of you would be kind enough to tell which of the most common cars, if any, have multiplexed circuitry....last thing I wanna do is have a brain meltdown over something like multiplexed cars....I know how to install with them, I am basically just looking for a lil forewarning, know what I mean.  Any help would be greatly appreciated....

Thanx in advance,

Đễẳ†ђş 12\/ Ĵęśŧē®™

I was working for a company called Mobile Installation Technologies (M.I.T.) based outta atlanta GA....they got the contracts, and the techs (like me) did the install....Mostly it was for SBC the last two or so years...you know the phone company that owns Ameritech, Pac Bell, Verizon wireless...just to name a few of their subsidaries.........

Well thank you.......

p.s. know anyone who needs that type of work done or an experienced installer doing it??  I liked it and the pay was great... But than again, I like anything 12V..

<stupid question>

ok, anybody wanna explain the term "multiplexed circuitry" to me? 

</stupid question>

JASON

Well dan.......

Let me get back into the groove of alarms...and maybe I'll be asking you to send me a few contacts....southern Cal...alot better than the Chicago Area!!!  I like the climate better!!

Oh crap, sorry Jason didn't see you post....

Multi-plexed circuitry in Leyman's terms:

Now I will use an example.  Say you are at the headlight switch hooking up an alarm...you test and find the 12V constant...than you turn it to the parking lights and get a wire putting out 5V and the parking lights come on...than you turn the switch to the headlight position and no other wires have juice, but the wire that had 5V is not putting out 10V..you turn it back to parking and it drops to 5V back to headlight it goes to 10V..it could be classified as a multi-plexed circuit.. Now note..I used volts, usually its in Amps or Ohms, but using volts makes it easier for me to explain, and hopefully easier for you to understand.

What multiplexed is, is the manufacturer using one wire, to do multiple tasks, by simply changing the voltage, amps, ohms etc.. what happens is the computer (or another device) deciphers the voltage, amps, ohms in the wire and intiates the operation to perform.

Now, here's the definition I was giving in school for it:

The nature of multiplexing is the transmission of information around the electrical system throught the use of computer data.  The data is in teh form of a binary code stream (100010100101) where the on/off pulses usually have an intensity of either 0 or 5 volts as the values for on/off.  This means all teh O.E.M. needs is a two wire loop throughtout the vehicle, and a group of slave modules that decipher teh code and turn it into a usuable output to drive a 12 volt realy, allowing the devices connected to them to operate.

--Mobile Dynamics, Phase 7 book, page P7-8--

That's why I did it in leymans terms first...

Word of advice, if you think you are dealing with a multiplexed circuit, go directly to the switch and clarify it..than add in the neccessary relays, resistors, diodes, whatever the situation calls for.

Hope this helped you out Jason