: Aftermarket HU/Data bus 2 bypass

07-28-09, 04:57 PM
Ok, lets start this off with I'm the kind of guy that just can't accept no for an answer...:want: I've been all over this place and noone seems to have the definitive answer on aftermarket HU installations. Most people have issues with security and door chimes. Frankly I could care less about the door chimes.

My question is has anyone successfully 'bypassed' the data bus 2 security link? Can the two purple wires just be mated to remove the stereo from the loop?

Also, I see a kit on ebay to add RCA amp connectors into the system for non-bose/non-factory amp'd systems that could be modified for my installation purposes. Only problem is that is only for up to '95. Anyone know if by chance the wiring harness going into the back of the HU is the same connector from '95 to '97?


07-28-09, 05:41 PM
95 and 97 are not even close to the same
where are you located

07-29-09, 12:30 PM
I'm in North-Central PA. Why you got a fix? Can you just hook the two purple data bus 2 wires together to exclude the HU from the security loop?

07-29-09, 12:32 PM
I see your location now. I live about 4 hours north of you in Potter County.

07-29-09, 02:40 PM
no you cannot
you need to hook up the gmos-03 or keep the stock radio somewhere and run new wires bypassing the bose

07-29-09, 03:10 PM
Dont have Bose, just the base tape deck. No changer, no amp in the back.

07-29-09, 05:35 PM
no bypass needed then
still need the 03 or to wire hu in the rear

07-29-09, 06:24 PM
ok...what exactly does the gmos-03 really do? and for $90?!
Description below:

"DATA BUS 2 INTERFACE The GMRC-03 is designed to be used in Cadillacís that do not have Onstar or amplified systems. It will retain the warning chimes that are lost when the factory radio is removed. The GMRC-03 will also provide a 12 volt switched accessory wire for proper radio operation."

I dont care about loosing door chimes or steering wheel controls for the audio and I can run a hot/accesory wire from the steering column to accomplish that. Are you saying that I don't have to worry about the security system if its not a Bose HU? I'm trying not to have to buy anything but the single din dash adapter.

Can you tell that I'm cheap?:sneaky:

07-29-09, 07:49 PM
Normally you don't need to connect the two data wires (E6 & F6) together. But if you have a network gap in the same loop then you WILL lose communication to the MMM module (if equipped). Also in the unlikely event of two network gaps (the one on the HU and some other) you can lose up to 3 modules from the network. This is why you have 2 data wires (refer to the DLC pages in the FSM). So ALWAYS connect the data wires together when removing a module (permanently).
I would recommend you against replacing the OEM stereo though, but then is not my car.

07-30-09, 08:57 AM
Sounds good. I'll be sure to let everyone know how I made out (or not..haha) once I get the single din dash adapter and get everything put together.

07-30-09, 08:00 PM
dummys the car into thinking stock radio is there without being there

08-16-09, 02:26 PM
called metra axxess and spoke to their tech support for the wiring harness. Here is the number if anyone wants to call:

1.800.221.0932 option 2

i told them what i have learned from here and was told that if i run a constant 12v wire from the battery to the yellow wire on the aftermarket deck and another constant 12v wire from the battery to the orange wire on the aftermarket car alarm in conjunction with using the gmrc-03, this problem would be solved. does this sound like it would work??? i was told that it was a 50/50 shot of the harness doing the job on its own but if it doesnt and i follow these instructions that it would be an 100% problem solver.

:hmm: :hmm: :hmm: :hmm: :hmm:

08-18-09, 10:08 AM
Well - so far, so good. I can't believe it, but I managed to get all the speaker wires correct the first try. Blew a fuse and couldn't roll up my windows or lock the doors because I crossed my power and accessory wires from the head unit (helps to have the directions handy...haha) Other than that, I only cut the wires that I needed - speakers, power ant., power wire, and the purple data bus wires. I looped the data wires together and no issues, so far. You do need to run some sort of constant power from another location over to the console in order to keep your memory for the new HU. As expected, the only thing I lost was the door chimes. The metra dash kit fit nicely but the color is just a shade off from the factory components, but I'm not complaining.

08-18-09, 10:46 AM
congrats badillac97!!! :D :yup: :D

not to rain on your successful parade, but how long ago did this occur? from my experiences in talking to someone else who has had the sleep mode issue, the problem doesnt occur immediately. i was told that it takes about 3 days to a week and a half before the sleep mode issue comes up.

i plan on starting my project either sept 18th or sept 25th as i have a few more things to get to complete my system. what all did you install for your system?

10-02-10, 08:40 AM
I am going crazy. Got a 96 Deville w base radio no amp cd or bose. Installed a Pioneer HU with Metra GMCR-03. I loose HU memory, Have no key left chime, or Headlights on chime or seat memory set chime, however, when I open the door it chimes 5 times then stops. Then when I start the car it also chimes 5 times. Other than that no chimes for anything. ????

01-05-13, 03:00 AM
Hey, did you end up connecting the two Class II Serial Data lines together? How did that work out for you? THREAD RESURRECTION! Just wondering how that worked out for you. Did you just splice the two data wires together or did you hook them up to the OEM? Just wondering what ramifications I may experience. Thanks a bunch!

03-29-14, 07:22 AM
I have a 2002 Cadillac Deville and cannot figure out exactly what wires are what as far as the speakers go... I have tan, purple, light greeen(x2), 3 bare wires with some weird clear sheathing around it, and two more I can't remember.. Please help

03-29-14, 09:55 AM
I would suggest you find or purchase wiring diagram(or a FSM) and a more accurate posting of wire type, colors etc. Also without knowing what RPO code you have(base radio, bose, etc) any response will be half a guess.