davesabo

I think this was my mess up. I installed a new radio in my 89. I followed all the wiring instructions. red power black grd.. ETC....I hooked up the GM wire for 'dimming' to the 'illumination' lead on the radio. the radio manual says this will have the radio dim, when the cars head lights are turned on. however when I turn the car on the dash is fine as it always has been. when I put the headlights on the dash goes black and the radio does not dim it is full bright.. head lights off dash is fine, heads light on dash off goes. what did i do wrong on the radio install?

65Z01

The Dimming wire is Gry; the Display Dim Signal wire is Brn.

You might try the Brn wire for the dimming??

AGENT 86

If you replaced a Bose unit, Brown is the one you want. The Grey is for the back lighting of Bose unit.

davesabo

cool-- thank you guys. . I am going to try to change it up. i will put the brown wire to the 'illumination' wire off the radio which is orange.

but will not having this brown wire hooked up correctly cause my dash to go black when the head lights go on? i'm more concerned about that then the dimming of the radio.

I will be back with info soon. Thanks for info so far.

davesabo

ok so here is what i found out. I did not check on the dimming wire yet. i did test the photo cell and it works; its gets bright, and it gets dim. I discovered when i put my thumb over the photocell and then put on the heads lights, as if it was night, the dash gets very very dark basically illegible. when the lights are on and the car is in the light the dash works fine. when i use the dimming function on the head light **** it does not change at all, I even twisted it a bunch of times to free it up.. nothing. it seems to be related to the photo cell or does that dimming wire still come into play?

65Z01

I think all will be fine but suggest that you first verify dash/headlight function with radio completely disconnected.

davesabo

yes there is no way around it. I have to pull the radio and see if it works again or at least hook the brown wire to the dimming circuit off the radio.
Ill Be back

davesabo

okay I did take the radio out and the gray wire was indeed hooked up to the orange 'illumination' wire of the radio I disconnected them. no change.. my question is this brown dash dimming wire, where should i hook it up to? To make my dash dim and work when the lights are on and it is dark. Im not 100 percent sure this is a radio thing. I do see a gray wire with a white stripe and a black single position connectot that is not hooked up to anything. Look forward to your replies...

davesabo

update I found the brown wire it was on a two pin black connector the other side was orange and it was cut off. where do i hook up this
brown wire? Thank you

Cliff Harris

The rheostat on the headlight switch only works when it's dark and the parking or headlights are on. The photocell over-rides it so the dash is bright when the headlights are on in the day time.

65Z01

With the radio disconnected do the dash lights work as before??

Thar Orn wire in the Brn & Orn pair goes to the Clock Power in the OEM radio.

The Gry/Wht wire goes from the OEM radio to the Heater and A/C Control Assy (C68 only) display dim signal.

davesabo

bummer, I was hoping to hear The brown goes here and your set"

Hi Cliff, thanks for jumping in. i dont know what the rheostat on the headlight switch is. but yes the photcell diming works, (goes light or dark depending on light outside)
The dash works fine with light outside,
the dash works fine whe its dark with headlights off.
the dash goes dark when its dark AND the head lights are on - headlights off dash is lit. put head lights on, dash goes dark.
any ideas?


65Z01
thanks for sticking with this thread
the entire radio is not disconnected. I can pull the plug out of the back of the radio very quickly. I figured since its just speakers, GRD, Battery switched 12v and remote, its pretty straight forward. I just started with that dimming wire, the gray one that I had connected to the radio. I was hoping that was it. but it wasnt. you told me this: 'The Dimming wire is Gry' where should I connect this wire?

so the orange and brown wire in the same connector can stay disconnected because there is no longer an OEM radio. Correct?

The Gry/Wht wire goes from the OEM radio to the Heater and A/C Control Assy (C68 only) display dim signal. I do have C68. it works but I guess it wont dim because this connector is not connected to the HVAC controller? if it needs to be connected I can pop that out and plug it in. or am i misunderstanding something?

lastly - so if it is not the radio, since it seems the gray/white and orange brn dont have anything to do with Dashboard dimming, what would cause this to happen? THANK YOU BOTH - I appreciate your input.

Hooked on Vettes

Sounds like the INST LPS 3 amp fuse is blown. It's located in the passenger end of dash fuse panel. Voltage on the fuse varies depending on the dimmer switch position when the headlight switch is in Head or Park.

The INST LPS fuse is the voltage source for the Gray wire.

Also your new radio might have a parameter to allow dimming or no dimming of the radio display which needs to be set correctly.

davesabo

interesting -- thank you hooked on vettes. I will check the fuse as soon as i get home. hopefully it is blown and that was the cause. (you think by now I would check the fuse first)
but the question remains -- do i hook up this gray wire up anywhere? or just tape it up and leave it disconnected.
same for the Brown Display Dim Signal wire that 65Z01 mentioned. where should I hook it up to?

Thanks you again. this is really helping me narrow this down.




same for the orange and brown one.. just tape them off?

Hooked on Vettes

You need to contact the radio manufacturer and ask them what type of dimming signal is required to control the display brightness.

Or you can attach either the Gray wire or the Brown wire to your illumination wire and see how the display reacts.

The Factory Brown wire has 12 volts on it when the headlight switch is On and Zero volts when the headlight switch is Off. Because of this the display will either be at full brightness or partial brightness.

The Factory Gray wire voltage varies depending on the dimmer switch.
This will cause the display to gradually increase or decrease in brightness.

The Factory Orange wire needs to be connected to your new radio memory wire. This wire is Hot all the time.

davesabo

hooked on vettes - you called it.. blown fuse. what a releif that was. maybe it was because i had the gray wire hooked up to the illuniation wire. who knows but im glad that was it.........im not that concerend with having the radio display dim anyhow. i will try the brown wire to the radio illumination wire and see what that does. so the gray wire is now taped off. the last thing to address is this gray and white wire with a black connector on it. you guys said its for the C68 hvac controller but i felt around back there and did not feel a place for it to plug in, there was just one blue wide connector. perhaps i missed it or it is underneath/below the blue connector. does this indeed plug into the back of the controller? if yes i will take it out and do it, i just wanted confirmation before i took out another part of the console.
once again i appreciate the info.

65Z01

That Gry/Wht wire goes from the Bose to the C68; it's the Display Dim Signal to the C68.

davesabo

aha... duuuh - ok so i got it -there is no more bose so that gray/white just hangs loose (and thats how i found it)..no where to plug it in.
so the hvac dispaly wont dim I guess and thats fine.
I think i can button it up now.
thanks for the help everyone.
much appreciated.