Illumination wire on a GM car with data bus 2

[Pulp_Fiction]

My car is a Chevrolet with the data bus 2. The dash lights all have 12v when the car is on and the on/off/dimming is controlled by varying the ground circuit. No, the Z1 does not handle a variable ground so I don't have the illumination hooked up. It is fine except the map is a bit bright at night. I figured I could find the appropriate wire over at the stalk or the fuse box. I can't see the power going to the main lights being the same way since they don't dim. I even thought about hooking the ill wire to my daytime running lights so I would remember to turn them off (they look bad on my car) but then realized they are also the turn signals and wouldn't want that strobe in the cab while waiting for a turn. lol.

If anybody has a GM car that dim's the dash lights this way how or where did you hook up your illumination wire. I don't want to use a relay.

[gerard143]

so all you need to find is a 12v lead that simply has zero voltage normally and 12volts when the parking lights come on?

give me the year model if so.

have you probed the headlight switch leads with a meter?

obd-ii style cars are weird. i've just started recently messing with aft-96 cars and i'm noticeing more and more weird shit.

like my 02 durango, every single fuse on the fusebox never reads voltage... wtf sense does that make?
then on my buds 1996 monte carlo he lost interior dash lights and all running lights.

i started probing leads and i found leads that I could use as a ground but then turned to positive voltage. i mean how is that even possible. how can a lead be ground and supply positive voltage when say ignition is on and not short out. everything i've ever worked with so far was one of the other.

anyways after figuring things out probing the headlight switch connector i got it all figured out and wired his lights so they simply get power when the ignition is on.

ducatiboy wrote...

I find it strange that your vehicle is a negative illumination wire. Does the head unit take care of this? The wire is 12V all the time and when you turn your lights on it will go to ground?

that is the same thing i noticed when probing this monte carlo.

[Pulp_Fiction]

[quote name="gerard143"]so all you need to find is a 12v lead that simply has zero voltage normally and 12volts when the parking lights come on?

give me the year model if so.[/quote]

Yes that is what I need.

Thanks,
2006 Chevrolet Corvette (not Z06) LT2 A6.

[gerard143]

to bad your on the other side of the coast, i could figure it out for you in probably 15 minutes if i was there.

[gerard143]

u might have to use a diode to isolate it. obd ii can get difficult.


im looking into this. i'll post back

[gerard143]

if the c6 is like the c5, the hvac control has a cream wire. chances are it won't be the same though. if so you can tap into that.

still researching for you though. you gotta get a multitester if you don't have one though, it should be cake to find a wire if you have one. just ground one prong.... turn on ur running lights and probe for 12 volts. when you find one, turn off lights till you get one that turns off with the switch.

the hvac lead should have 12v switched power when find that lead and tap it there.

[Pulp_Fiction]

Heh, you edited your post after I replied. More questions now.

Headlights: Didn't probe them, I was only looking in the center console. They are my "sure thing" I'm hoping.

ODB-II: Yeah, throw on top of that GM uses their Databus II to complicate it more. Everything, even the stock radio gives feedback through it.

[gerard143]

sure are correct there. i got a durango i just bought and im adding an autpage rs-860 lcd 2 way alarm and an avic-z1 real soon.

besides having to chop apart the dash trying to fit a double din in a din and 1/2, wiring gets complicated to.

atleast the alarm uses a databus module and taps into a lead on the obd-ii connector to simplify shit.


i'm not familiar enough with the new vettes, but im assuming your center console has lighting that apparently turns on with your running lights. ya if so you might be set there.


i'd have to stop up to the dealer and review some wiring diagrams to get a definate answer on which lead to connect to.

any other way and ur gonna have to start ripping some things apart getting to connectors and probing leads.

[Pulp_Fiction]

Here is a pic of the primary radio connector.

No Pics of the HVAC but they did change the system a lot between C5 and C6
[img]http://download.msleet.com/corvettepics/radioconnector.JPG[/img]

[Pulp_Fiction]

[quote name="gerard143"]sure are correct there. i got a durango i just bought and im adding an autpage rs-860 lcd 2 way alarm and an avic-z1 real soon.

besides having to chop apart the dash trying to fit a double din in a din and 1/2, wiring gets complicated to.

atleast the alarm uses a databus module and taps into a lead on the obd-ii connector to simplify shit.


i'm not familiar enough with the new vettes, but im assuming your center console has lighting that apparently turns on with your running lights. ya if so you might be set there.


i'd have to stop up to the dealer and review some wiring diagrams to get a definate answer on which lead to connect to.

any other way and ur gonna have to start ripping some things apart getting to connectors and probing leads.[/quote]

Actually the lighting turns on with the ignition mostly, not the running lights. Additionally the turn signals double as daytime running lights. I figure I should be able to get power from the line leading to the rear license plate light. It and the headlights are about the only 2 normal circuits. LOL.

[gerard143]

enough to drive you nuts isn't it?

license plate light leads a good idea. gotta be an easier lead to get to though. im still thinking hvac connector.


hmmm where can i find me an 06 vette to play with.
i should go test drive one and say i wanna take one for a few hours to get a better feel for it. haha, they've offered me that before.

then i can figure it out for ya.

[gerard143]

boy do you have the onstar and chimes issues to?




All class 2 radios will have door chimer built in. If you dont hear the chimer coming from the driver speaker then it's not class 2. I dont think RDS plays any role in class 2 databus.

On a class 2 databus radio, a single wire (thin orange wire) can do
01 ignition control. turn the key off and remove the key, the radio continues to play until the door's open.
02 illumination control. turn on the parking lights and the lights on the radio dims
03 door chime. GM got rid of the chimer circuit and built it into the radio. All warning chimes come from the driver speaker.
04 Onstar control. Allows onstar's audio to play through the radio's front speakers and mute the rear speakers
05 XM control. Allows controlling the GM XM satillite slave receiver. Audio is through the line input of the deck
06 various vehicle function control and programming. resets low tire pressure warning, oil change service warning, keyless entry programming
07 VIN number ID. class2 databussed radios are not interchangeable. They have VIN lock on it. You can't pull a radio out of an Impala and stick it in a silverado.
08 VSS controlled volume. The faster you travel the louder the radio gets.


In 2000, GM introduced what they dubbed the Class 2 Data Bus. The Class 2 Data bus allows the PCM (powertrain control module) to communicate with other parts of the car, such as OnStar. There's really nothing wrong with this until you want to install an aftermarket car audio system.

Basically, GM integrated the user interface of the Class 2 Data Bus into a familiar user interface: The radio. This sends chime signals to the front speakers, should there be something that needs your attention, such as the turn signal is on too long or OnStar tries to tell you something. If you remove the factory radio, you lose the chimes as well as OnStar. Removing the factory radio will light up the "Service Soon" dash light. The Class 2 Databus also checks for the presence of the amplifier, if so equipped.
.

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[ducatiboy]

[quote name="gerard143"]if the c6 is like the c5, the hvac control has a cream wire. chances are it won't be the same though. if so you can tap into that.
still researching for you though. you gotta get a multitester if you don't have one though, it should be cake to find a wire if you have one. just ground one prong.... turn on ur running lights and probe for 12 volts. when you find one, turn off lights till you get one that turns off with the switch.

the hvac lead should have 12v switched power when find that lead and tap it there.[/quote]

You don't need 12V constant when the lights are on, most cars have a dimmer switch which is a signal which goes from 12V to ground very quickly and is what the car uses to dim the interrior lights. It will measure something like 4-8V on a meter.

And if you have a dimmer knob which makes the interrior lights dim and are adjustable, you can pull it off that. If you measure that line it will be ground when off, but 5V when the lights are on (on most meters) and it's a signal which goed between 12V and Ground which is very very fast and most meters will average them over time, so it comes out as 6V or something. But it will dim your interior lights. My circuit is designed to handle this signal as well and I think so will the Z1. If you have a meter and you see something that goes between ground and 5 volts, try adjusting the dimmer in the car to see if it changes and if so, put it on Volts AC and you should register some AC voltage on that line. If so, that's the wire.

You can use that as well. Or 12V constant when the lights are on, that works too.

[Pulp_Fiction]

[quote name="gerard143"]boy do you have the onstar and chimes issues to?




All class 2 radios will have door chimer built in. If you dont hear the chimer coming from the driver speaker then it's not class 2. I dont think RDS plays any role in class 2 databus.

On a class 2 databus radio, a single wire (thin orange wire) can do
01 ignition control. turn the key off and remove the key, the radio continues to play until the door's open.
02 illumination control. turn on the parking lights and the lights on the radio dims
03 door chime. GM got rid of the chimer circuit and built it into the radio. All warning chimes come from the driver speaker.
04 Onstar control. Allows onstar's audio to play through the radio's front speakers and mute the rear speakers
05 XM control. Allows controlling the GM XM satillite slave receiver. Audio is through the line input of the deck
06 various vehicle function control and programming. resets low tire pressure warning, oil change service warning, keyless entry programming
07 VIN number ID. class2 databussed radios are not interchangeable. They have VIN lock on it. You can't pull a radio out of an Impala and stick it in a silverado.
08 VSS controlled volume. The faster you travel the louder the radio gets.


In 2000, GM introduced what they dubbed the Class 2 Data Bus. The Class 2 Data bus allows the PCM (powertrain control module) to communicate with other parts of the car, such as OnStar. There's really nothing wrong with this until you want to install an aftermarket car audio system.

Basically, GM integrated the user interface of the Class 2 Data Bus into a familiar user interface: The radio. This sends chime signals to the front speakers, should there be something that needs your attention, such as the turn signal is on too long or OnStar tries to tell you something. If you remove the factory radio, you lose the chimes as well as OnStar. Removing the factory radio will light up the "Service Soon" dash light. The Class 2 Databus also checks for the presence of the amplifier, if so equipped.
.

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[url=http://www.logjamelectronics.com/pacos2bose.html]http://www.logjamelectronics.com/pacos2bose.html[/url][/quote]

Isn't that just a great system if you want to leave it alone!!! LOL

No Onstar. Yes the chimes used to come from the speaker. The aftermarket adapter sends a false signal to the data bus to tell it the radio is present and working fine as well as provide a micro speaker to play chimes for me.

I went and looked at the dash again and even with the lights off most of the dash lights are on. The exception is the HVAC buttons, not the display or the knobs. The buttons do dim with the rest of the system but Ducatiboy says I don't need 12v so that might be a good source. I will hunt again when I pull out the TR7 and put in Ducati's module.

Ducati, yes I recall the voltage changes with the dimmer. 12V when off and down to ~6v when very dimmed. heh. Now if I can find the HVAC button line it may be what I want. Otherwise I'll use the license plate feed. The line should come to the front of the car since it does not blink like the tail lights and side lights.

[edrock200]

Illumination wires for Chevy's
2006 - Gray in stereo harness

If not available

Parking Lights + Brown + @ Harness going to rear of vehicle

Unfortunately the parking light reference above is for a 05 vette, couldn't find anything for 06.