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Yeah, I always fuss over this stuff, too. This is Me Precious, my 2003 50th Anniversary Corvette. They came with that junk GM radio from the 80's, redid the center stack to take a double din and put in a Panasonic AVIC-Z130 (I've since moved the phone mount to be right under the right hand on the left side of the console). I like the full 7" touchscreen, probably going this way for the V.

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Pioneer.
 

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Can you guys clear up something for me:

In doing this mod, are you retaining the *radio* from the poverty-spec CTS, as well as its DIC screen? I think what you guys are saying is that the radio has to be retained in order for the DIC screen to work.

So you keep the poverty-spec CTS radio as functional (getting it re-programmed to match your V at the dealer), but then simply delete the CD player from it to give space for a new *additional* head unit. Correct?

That is, you plan to have two radios in the car, one new double-DIN head unit, and also the poverty-spec CTS radio --- which I guess will be unconnected to the speakers, and exist there only to make the DIC screen continue to work.

Is this correct?

Thanks for the clarification. This looks like the way to go, if I understand the project properly.

Nothing like a deadline to force progress. :lol: Car goes into the shop on Thursday for the big install and I had to get this base model radio conversion done. Very easy process, just time consuming to do it carefully. I made a pretty conservative cut into the faceplate to leave my installer room to properly size the opening for the double din head unit.

View attachment 168394
View attachment 168402
 

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Yes, the radio in the base model head unit will continue to be powered but will not be connected to speakers or an antenna. Yes, the net result is a fully functioning DIC screen that displays all messages previously sent to the OEM NAV screen. I had a very similar install in my Subaru Legacy because the factory headunit was integrated with the HVAC controls and could not be easily separated. The only time anyone ever turned on the factory radio was when the car came back from a valet :lol:
 

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2004 V (B&M, muffler delete), 2003 Corvette
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Discussion Starter #45
Yes, the radio in the base model head unit will continue to be powered but will not be connected to speakers or an antenna. Yes, the net result is a fully functioning DIC screen that displays all messages previously sent to the OEM NAV screen. I had a very similar install in my Subaru Legacy because the factory headunit was integrated with the HVAC controls and could not be easily separated. The only time anyone ever turned on the factory radio was when the car came back from a valet :lol:
I am tentatively planning to go a different way, and keep the base radio/XM taking the audio out into an aux in on the new head. The radio & XM should then function normally, including scan and select buttons. I guess both volume controls will affect the output, but the alternative is having all those dead buttons. To each his own poison, I guess.

Still shopping head units & planning (a Lotus Elan+2 project is soaking up my time right now).
 

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I saw a thread either on here or ls1 tech that someone did downgrade and install a nexus 7, I'm in the process of doing this as well. When the radio gets in I'll try to document the hurdles.
 

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Car is at the shop getting the install done now. My installer sent me a few photos last week, can't wait!




 

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Okay, so the CTS DIC is in and programmed. I think the shop that had the TechII missed a few paramters when they programmed my radio. I can scroll through all info options and the last option is trans fluid life, obviously a feature for automatics. The owners manual mentions display of individual tire pressures, I don't get those. I can't change the key out, door lock feature. The option is there, but I can't add a check mark next to it. And the last thing is competitive driving mode. I can enable it with the steering wheel controls, but it's not displayed on the DIC, which I assume doesn't know it's in a CTS-V. Stability control messages appear properly, but no CDM. All message clear on their own with the exception of the oil change message that I haven't reset. You have to press the CLR button to clear that message.

Long story short, the conversion works flawlessly with the exception of a few bugs I attribute to the difference between the CTS and CTS-V that weren't programmed properly, but I can easily live with those.

DashSm2.jpg
 

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2004 V (B&M, muffler delete), 2003 Corvette
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Discussion Starter #49
My test with a base radio DID offer the Competitive Driving Mode prompt on the DIC. I still just have the empty hole where the new unit is supposed to go, but the prompts did display and did work.

I didn't check all the options in the info, I'll have to put the test unit back in to do that.

I did have the dealer reprogram the base radio for the car (I assume you did that, too), maybe there was something in the setup there for the V differences, I dunno.
 

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This has been a very useful thread, and thanks especially to JGeezer & fweasel for their posts.

new_head_unit.JPG

I have now successfully followed in their footsteps: bought the low-spec CD player on ebay, and had it de-THEFTLOCKed at the dealership for a half hour of their shop time ($67). Then I pulled it out again to hit it with a torx T10 screwdriver, and a dremmel with cut-off disks, as outlined in the DarkWingFrog guide linked earlier by JGeezer - http://www.cadillacfaq.com/faq/answers/aftermarketradiodic/index.html

The DIC works just as JGeezer describes. No problem with displaying Competitive Driving Mode messages, as fweasel experienced.

I want to comment on the wiring aspect of this project. The DarkWingFrog guide does not deal with that aspect. But if you are the kind of person who is unafraid at the prospect of hacking up circuit boards with a dremmel tool, then wiring the new head unit should be the least of your worries.

The easiest solution and closest to "plug & play" is to connect the new head unit directly into the car's existing Bose amplifier and speakers. This way, the Bose amp is still operated by the DIC & its various buttons, so functions like front/rear fader control, warning chimes, and other Bose sound effects continue to work as GM intended.

The pins of the CTS-V radio harness are identified in this diagram:

http://www.cadillacfaq.com/faq/answers/pdf/connectors.pdf

The 20-pin yellow/green/blue connector and the 8-pin grey ISO connector from the CTS-V harness, will continue to be plugged into their respective ports on the factory DIC radio (ie. the top and bottom of the three plug ports).

Nothing will be plugged into the middle port on the factory DIC radio.

The remaining 8-pin brown block in the CTS-V harness carries the front speaker wires, right & left, (+) and (-) to the Bose amp. Hopefully your new head unit will come with an ISO connector wiring harness. In that case, this brown plug may be plugged into it. Double check the wiring code for your new head unit, because its ISO speaker connector may not perfectly match the pins in the CTS-V harness. In the harness for my new head unit, although all the front speaker wire pins matched perfectly, the head unit's ISO pins would have connected the rear speaker output to the drain wires and vehicle speed signal in the CTS-V harness (ie pins 8, 2 and 7). So I simply cut the rear speaker wires from the head unit's ISO connector. Leaving the drain wires unconnected (pins 8 and 2) has not caused any perceptible speaker hum, but YMMV.

So at this point, all three connector plugs are employed from the CTS-V harness, but you still need to get power and ground to your new head unit. There are several ways to go about doing this, but I will recount my choice.

First, I cut the unused ISO connector from the head unit's harness, so I could get three wires free for soldering: the yellow wire (constant 12v+), the red wire (switched ignition 12v+) and ground wire (black).

The yellow and the black wires are simple to deal with. The red is a little more tricky.

For constant battery power, I used the cigarette lighter 12v+ wire. That stupid thing is completely worthless anyway, unless you never shift into 3rd and 5th gear. My new head unit has USB jacks for charging purposes, if it ever comes to that.

There are obvious ground sources for the black wire everywhere inside the hollowed-out centre stack area, when you are staring at the firewall. Pick a bolt and test for ground continuity with a multimeter.

The last issue is a source for the switched 12v+ red wire. There is a thread here that I can't find at the moment, where the dark brown wire from the HVAC control-head harness gets tapped directly for this purpose. I'm not keen on asking that wire to handle unforeseen current, so I wired up a relay to reduce the draw. Standard 4-pin automotive relay wired this way:

85 - ground (shared ground point with the head unit)
86 - tap into dark brown HVAC wire (test it with multimeter first, should be 0 v+ ignition switch off and 12v+ ignition switch on)
30 - tap into cigarette lighter 12v+
87 - goes to head unit red wire (switched ACC terminal on head unit)

Hope this helps someone else.

If you can do the DarkWingFrog mod, you can do the wiring, too.
 

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'04 CTS-V, '07 SRT8 Jeep, '86 Fiero
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Awesome. I'm definitely going to be doing this eventually.
 

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I would really like this done in my V..but I am no where near technically inclined to even fathom taking this upon myself to do...
From what I've read I would have to take the aftermarket radio..which would be installed prior to going to the dealership to have them program the aftermarket unit...?
If you dont mind. ...PLEASE WALK ME THROUGH THE STEPS. ..
and if you live in socal...or 300 or less miles closer. ..please tell me where your fabricator is located so I might be able to have this done...any info would be much appreciated!!
 

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2004 V (B&M, muffler delete), 2003 Corvette
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Discussion Starter #54
I would really like this done in my V..but I am no where near technically inclined to even fathom taking this upon myself to do...
From what I've read I would have to take the aftermarket radio..which would be installed prior to going to the dealership to have them program the aftermarket unit...?
If you dont mind. ...PLEASE WALK ME THROUGH THE STEPS. ..
and if you live in socal...or 300 or less miles closer. ..please tell me where your fabricator is located so I might be able to have this done...any info would be much appreciated!!
No, the dealer programming is only to get the base factory radio to work. We're doing all this to keep the info (temp, miles to empty, etc.) and the "OK" so the steering wheel controls for competition mode & the like still work, through the small base unit. A strange radio will be assumed stolen and rejected by your car otherwise.

The whole idea is to empty a nice big hole where a double-din modern touchscreen can go - but this is where there are a number of ways to go, and it sounds like you should use a pro.
 

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2007 CTS-V, 1984 Coupe De Ville
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Yes... If you look through a Crutchfield catalog or their web site, on all the compatible nav radios (that I've seen), it will tell you something like "Yes, this radio will fit, but you will lose your onboard driver information system."
 

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cilpherv04, if you show this thread to your local car stereo shop, they could tell you whether they would undertake the work. I would be very curious what they would charge you for that, and whether they would offer you a warranty, if you would share that info.

Yes... If you look through a Crutchfield catalog or their web site, on all the compatible nav radios (that I've seen), it will tell you something like "Yes, this radio will fit, but you will lose your onboard driver information system."
I bought my Parrot Asteroid Smart from Crutchfield. They want you to buy a package that includes a PAC OS-2C-CTS with CM1 chime module, and a replacement plastic faceplate (Metra 99-2006C), and an antenna converter plug (GM to Motorola jack). This is because they expect that you will torpedo your GM stereo altogether.

I would advise against buying this package, if you're going to do the mods in this thread and retain the DIC. Only the antenna converter jack is of any use from the Crutchfield package. The new faceplate and the PAC are not used.

The PAC device is the aftermarket stereo industry's answer to losing the DIC. The PAC snaps into the three vacant plugs of the CTS-V harness, once you pull out the factory radio. It converts the ISO plugs on the CTS-V harness to common aftermarket stereo wiring codes, for easy soldering to an aftermarket head unit's harness (ie. the usual loose wires of black, yellow, red, etc., at the opposite end to the ISO plugs). Also, the "black box" in the PAC harness preserves some warning chimes and OnStar functions.

But obviously, even with the PAC device, you lose all of the Bose controls, and all of the DIC's other features. (edit - Maybe you retain more Bose controls when using the PAC, if your late-model V1 has steering-wheel stereo control buttons. This was a moot point on my 2005 car, without those buttons).
 

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I saw a thread either on here or ls1 tech that someone did downgrade and install a nexus 7, I'm in the process of doing this as well. When the radio gets in I'll try to document the hurdles.
anything worth mentioning? looking for ideas on how to modify the HU to accept the tablet.
 

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A couple of additional points for "fine tuning" that are worth mentioning.

(Issue 1) I thought it would be nice to use the RAP circuit to trigger the aftermarket stereo to power itself on/off, instead of tapping the HVAC wire that I mentioned above. That way, the aftermarket stereo would stay powered up for 10 minutes, or until a door opened, just like the DIC/factory head unit. This turns out to be pretty difficult to achieve.

There is no 12v+ signal in the DIC harness that triggers the DIC to power itself on --- it must be a Class II data digital signal that does this. So it's not possible to rig a simple relay that triggers your aftermarket head unit as soon as the factory DIC powers itself on.

There are a few threads around here suggesting that an RAP relay exists in the back-seat passenger-side fuse box, and if you have that relay, then it would be pretty simple to tap that one for a RAP signal for your aftermarket head unit.

However, when I looked at my fusebox, there was no such relay, even though I have a sunroof. I believe that RAP relay only exists on sunroof-equipped cars built prior to the late-2005 model year -- http://www.cadillacfaq.com/faq/tsb/data/pic3355.pdf

2005 CTS built prior to VIN 1G6DP567850125773 will have the RAP relay as part of the Sunroof wiring harness located below the right rear sail panel and is accessed through the trunk. 2005 CTS built after VIN 1G6DP567850125773 will have the RAP relay integrated into the Sunroof motor assembly.
So if you have a newer car, that RAP relay is part of the sunroof motor assembly, so there is nothing to tap either in the backseat fuse box, or in the wiring under the passenger-side C pillar in the trunk. Nothing simple can be tapped which only becomes 12v+ "hot" when the RAP is engaged. Quite disappointing, because I don't have enough ambition to pull the headliner just for this tweak... I'll live with the HVAC tap that I described above, at least until I'm forced to service the sunroof assembly.

Below is a photo of my fuse box, with the sadly empty RAP relay socket in the bottom-right position (no wiring goes to that socket, either, as shown by the underside photo of the fuse box).

1024-1.JPG

1024-2.JPG


If anyone sees an error in my assessment here, or has a great solution to tapping the RAP circuit for a relay, for late-2005 cars and newer, please post up.

(Issue 2) The LEDs behind my right-hand rocker switch do not work when the rest of the instrument panel lights up (ie. the CLR, INFO and arrow up/down rocker switch). This was a minor annoyance, but I stumbled on the solution while searching for info on the RAP circuit. It's apparently a pretty common issue arising from this mod, because you end up having to cut the LED trace in the circuit board to make enough room to mount a lot of double-DIN head units. This guy came up with an elegant solution --- look at Post #2 for a description and photo of a jumper wire that can be soldered into place that will re-activate these LEDs:

http://www.cadillacforums.com/forums/cadillac-cts-first-generation-forum-2003/236057-complete-guide-1st-gen-cts-navigation.html

Thanks very much to fweasel and JGeezer for their PM help in trying to fix this last issue on my DIC. I think all three of us missed seeing that thread suggesting this is a common problem, and the jumper wire is its solution.
 

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(Issue 1) I thought it would be nice to use the RAP circuit to trigger the aftermarket stereo to power itself on/off, instead of tapping the HVAC wire that I mentioned above. That way, the aftermarket stereo would stay powered up for 10 minutes, or until a door opened, just like the DIC/factory head unit. This turns out to be pretty difficult to achieve.
Issue 1 is now solved, without having to drop the headliner, thanks to help from a couple of guys at the LS1tech forum: jamesdem1123 and bigassogre.

To get this done, you have to tap a wire at the Rear Integration Module (RIM). This requires that you pull off the parcel shelf cover behind the rear seat, like so: http://www.cadillacfaq.com/faq/answers/reardeck.html

Although I didn't remove the seat back completely from the car, it probably would have made life easier to do that, because otherwise you are going to have the passenger-side headrest right in your face as you do the rest of this job.

You need to tap the "RAP relay coil control" wire at the RIM, if your CTS-V is late 2005 or newer. This is a tan coloured wire, labeled "755 circuit" on wiring diagrams that show the pin-outs for the RIM. The Alldata diagrams that are floating around the internet only deal with the early-production cars, where the 755 circuit went from the RIM to a relay in the back-seat fusebox. Later production cars, like mine, used the same pin on the RIM and same "755 circuit", but the tan wire goes directly up to the sunroof module without first visiting the back-seat fusebox.

The diagram is here for the early cars: http://www.cadillacfaq.com/faq/answers/img/schema/rap.jpg

After you pull the parcel shelf cover, you will see that there are two connector plugs that go into the RIM, one red one (C1) has 16 pins, and the brown one (C2) has 24 pins.

The pin you want on the RIM is A1 on the C2 (brown) connector. That's the "755 circuit", the "RAP relay coil control".

On my car, it is the top-most pin, closest to the front of the car.

The RIM is easy to remove, to give yourself access room to deal with that wire. The RIM has 3 expanding push-pins that hold it to its base, like the kind used in holding the front bumper cover and wheel-well inserts in place.

Here's a photo of the two RIM plugs sitting loose with the RIM module removed. You can see where I scraped some insulation from the tan "755 circuit" wire at pin A1, in preparation for soldering a new wire to it:

1024-2.JPG

Once I soldered a new wire to that 755 circuit wire, I snaked it through the car, under the plastic passenger-side door sills, around behind the glove box, and into the centre stack area.

Once I had led the wire there, I re-wired the relay that I described above, in post #51.

The "755 circuit" wire switches to ground at the RIM when RAP is active or ignition is "on". So the new relay in the centre stack needs to be wired like this now:

85 – Tan "755" wire from the Rear Integration Module
86 - 12v+ constant
30 - 12v+ constant
87 – red wire to aftermarket head unit

That's it. Works like a charm. Now the aftermarket head unit powers itself on at the same time as the DIC does, and it remains powered on after I switch the engine off, just like the DIC. They both power off simultaneously as soon as a door is opened.

Hope that helps someone else. Obviously it's more work to do this than simply tapping the HVAC wire that's sitting right there in the centre stack, but to me anyway, it's way more satisfying to have the new head unit working according to the car's RAP logic.
 
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