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Buick LeSabre Radio - 2000 into 1995


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avatar307 
Member - Posts: 1
Member spacespace
Joined: December 18, 2004
Location: United States
Posted: December 18, 2004 at 1:10 PM / IP Logged Link to Post Post Reply Quote avatar307
Alright, I've got a interesting situation for comment. Why so interesting? Because it's largely the opposite of what everyone else is attempting. I'm trying to install a factory headunit... Specifically, a 2000 LeSabre headunit into a 1995 LeSabre.
My LeSabre came with a stock cassette player. I don't like any of the aftermarket CD options, so I decieded to just upgrade to a factory CD headunit. Due to the unique design of the Buick radios/dash, I am not alone. Thus, used 95-99 Buick headunits are go for $100-200.
I refuse to pay that much for a factory radio... so I bought a 2000 LeSabre headunit for $20. This is one of the first "lock-and-dock" style Delco radios, and is unique in more aspects than one. Not only does it use the ribbon-cable/circuit-board type connector, but it has the VW/BMW/Volkswagon antenna connector.
Thus far, I have overcome all the physical obstacles to installing a 2000 headunit in a 1995. Thanks to 4 Scosche adapters, I can connect both the radio and the antenna to the factory/GM-standard 32-pin and mini/Delco antenna connectors. Unfortunately, that is has proven to not be enough.
As the 2000 LeSabre headunit is so unique, I had hoped that internally the radio remained the same as the 1999. Physically, the 2000 headunit looks the same as the 95-99 style. It predates the current Buick "RDS-style" radios, and thus likely predates a lot of the Class 2 stuff.
It has become apparent that the radio does have at least some minimal serial communications requirements. The Scosche reverse wiring harness for the radio includes a +12vdc Ignition lead, but that apparently is not what actually turns the radio on.
There is +12vdc Battery/Constant power to the radio.
--The Theftlock LED flashes as though the ignition was turned off.
--The CD Eject button works.
--The display will momentarily show 12:00 when the Recall button is pressed.
--If the Minute-set button is pressed and held, the radio beeps once and momentarily displays 12:00 when the button is released.
Therefore, I have concluded the radio simply does not know when it's supposed to turn on.
The Scosche reverse wiring harness for the radio includes 6 brown wires that have no listed purpose. Brown is not a color listed on the back of the Scosche package. The text printed on the wires says "Dimmer," but that's obviously not their purpose. For one, there are 6 of them. For another, the harness includes an Orange "Dimmer/Illumination" wire, which correctly triggers the dimming and illumination of the headunit when +12vdc is applied. -- E-mails to Scosche Tech Support as to the purpose of these wires have not been returned.
I have spent hours with an multimeter meter mapping out the radio pins and comparing their behaviors to the 1995 headunit. (As I actually have a known pin-out diagram of that connector. I have yet to locate one for the "lock-and-dock" or 2000 LeSabre radios.)
Two of the pins are strangely unique, B1 and B2. They have 0 ohms resistance to each other, but infinate resistance to all other pins. These are the only UNKNOWN pins with any observed relationship, and they also happen to be 2 of the 6 pins the have brown leads associated with them.
The pin-out diagram for the factory radio plug in my 1995 LeSabre lists two Data lines. E&C Data and VFPWM Out, pins B1 and B4 respectively. E&C Data is Entertainment and Communications Data, beyond that I have no clue. As for VFPWM, my guess is Varible Frequency Pulse Width Modulated serial data...
GM uses the VPW, or Varible Pulse Width Modulated, standard for OBD-II diagnostic commincations on 1996 and later vehicles. My bet is VFPWM is an older abbreviation for VPW. From what I read, VPW and GM Class 2 Data Bus are one in the same.
(Note: Ford uses PWM, Pulse Width Modulated, for their OBD-II communication. PWM requires 2 wires, whereas VPW only requires 1.)
Obviously, my next step was to try connecting the E&C Data and VFPWM OUT lines to the brown wires on the harness. This was not an easy or rewarding task. I basically went through every possible combination of connecting the E&C Data and/or VFPWM OUT to each of the brown wires. The ignition was cycled between OFF and RUN on each wire change.
No results were yeilded... none. I did all this in the dark with a flashlight, and actually had a reason for doing so. When the plug is connected to the radio, the display lights up briefly with 5 thin red lines. (The purpose of which I do not know.) Pressing any button on the radio causes these 5 lines to briefly appear again. In the daylight, you cannot see the lines come on. Thus, I did it at night so I would be sure to see any reaction from the radio.
At this point, I was running out of wires to connect. Next, I connected each wire to ground. I had checked all the brown wires for voltage initially, and found none so I saw little danger in this. As expected, no results.
Next, +12vdc to each of the brown wires. (Don't worry, I included a 5A fuse in my jumper.) This time, I actually managed to get a reaction from the radio. When +12vdc is applied to the "unique pins" I mentioned above (B1 and B2), the red lines on the display immediately come on and stay on. A few seconds after the +12vdc is removed, the lines turn off.
This is the same as when any button is pressed on the radio. The lines light up and after a few seconds they shut off. Two important differences though. 1) The radio does it in response to line voltage, and 2) the lines stay on continuously until the voltage is removed.
This makes for a pretty convincing argument that those two pins are the serial data lines and that the radio ignition sense is a function of the serial data line. This is similar to how radios function in 100% Class 2 Data Bus systems that have been discussed here and elsewhere. More specifically, the use of serial data lines to turn components on and off.
For those who don't know. Instead of running a seperate wires to modules to turn them one and off, there is a serial line that connects all of them to the computer. Then the computer sends a signal out that tells the induvidual modules which "power-mode" they should be in. So instead of running 3 wires to switch a module into 4 modes, they run 1 wire that sends 4 signals for 4 modes.
So basically... that sums up where I am currently, and brings me to the point and the purpose of this post. (For those of you who actually read this far, you were begining to think there wasn't one huh?)
My problem is one of those simple to say, hard to explain, and even harder to fix problems. Basically, the radio doesn't know when the car is switched on because my old 1995 computer doesn't know to send a signal down the serial line telling the radio to turn on.
Is there anyone here with any knowledge of how the Class 2 serial bus actually functions? I.e. The specifics of the signal the computer sends to turn the radio, or any other module in the vehicle, on.
My goal being to build a device that will send the needed signal to turn on the radio when it detects Ignition voltage. I.e. A device that converts "+12vdc Ignition-sense" to "Serial Power-mode signals."
In one sentence, I need to replicate the "On-Awake" serial data signal so the radio knows when to turn on.
Thanks to all who actually read this all the way through, and many more thanks to anyone who has anything to say in reply.
-MC

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