: 1997 Seville Radio Replacement Recap/Help

05-13-09, 06:24 AM
Okay, I thought from perusing other sites that just an aftermarket integration harness was going to be needed in order to replace a stock head unit (non-Bose, no changer, just AM/FM/Cassette). It appears that utilizing the GMRC-03 adapter is basically a non-issue as people end up with data bus issues. I have read about "rewiring the car." That's no big deal for me at all as far as running everything. I plan on new head unit, amps, speakers, etc.

I see some people have moved the stock HU to the trunk to maintain the data bus integrity also. At this point, I'll be doing what I need to do the job, but would like to be pointed in the direction of a clear/concise drawing or explanation if possible. This is partly for time.

Or has anyone found that one of the newer/alternative data integration harnesses clears up the data bus issue? For example, I know on some of the aftermarket replacement struts/shocks, a resistor is used to simulate the electronics, thus faking out the ride control system from setting error codes.

Any help would be much appreciated, and thanks.

05-18-09, 11:26 AM
Alright, I am in kinda a similar boat - 97 DeVille without bose and with onstar...

I actually just ripped everything apart yesterday and dove in. I was planning on moving the head unit to the trunk and all and such but after having some difficulty with the pin outs on the factory harness, decided just to leave the headunit disconnected for a while and take a cruise around. No flags at all actually. I think that 98 and up is when the data became an issue, however, I am not positive on this - some verification from somebody else would be nice.

I currently am half way through the install and waiting for my mounting bracket - so the aftermarket hu isn't in yet, but things are going well otherwise. I plan on just jacking the 6x9s from the harness and otherwise I am putting in new speakers/wiring. Aka, not using a 3rd party wiring harness, just tapping wires into the eclipse one on the aftermarket hu.

Feel free to PM me if you have any questions about removing stuff or whatnot - I'll share my "caddy traps" I've found so far and give ya some advice assuming the seville is similar to the deville.

If anybody could verify that the 97s don't have the data issues it would be great.

05-19-09, 03:34 PM
Thanks for the feedback. I'm still waiting for all of my parts to show up. I also found the remarks surrounding the use of the GMRC-03 adapter that didn't solve some keyless entry or module sleep issues. I contacted Metra Tech support and provided a link to the discussion. Here is what I got back:

Thank you for the link. The problem that is being referred to in that forums is a vehicle problem not a interface problem. From 1996 to 1999 Cadillac made the G.E.M. module part of the factory radio. This is in some, not all Deville's, Seville's, and Eldorado's. There is no rhyme or reason on which radios or models they do this on. This is why I am saying some cars. There is a way to get around this issue. Simply run a constant wire from your battery to the constant wire behind the radio and attach it inline (without interrupting the wire). If you have the issue with the locks (which is not all cars) run a constant wire from your battery to the keyless module in the trunk. Attaching it to the constant wire again not interrupting the wire, just tapping into it. If you have any other question feel free to give me a call. I will be here till 5:30 eastern time.

It appears to me that the "safest way" to replace the radio is has been discussed and documented very well by moving the original head unit with the appropriate guidance as discussed in other posts (Thanks to all on the info sharing!!!!!!!!!!!).

However, it also appears that this is a hit and miss proposition as these model years were in transition electronically to new data bus integration. My plan right now is similar to yours. I am going to go for the straight forward replacement, but since I am running all new wiring anyways, I am going to run the spares necessary to relocate the head unit just in case. That way I only have to rip everything apart once, and $10 in cable is nothing if needed.

05-21-09, 08:43 AM
I was planning on relocating mine but all was good when I drove around without the OEM one plugged in. I'd just plan for the worst and see what happens.

Good luck with it =)