88 xlt radio help

[Brain75]

On your Boss wiring sheet, go with Boss Red to truck Yellow/Black; Boss Yellow to truck Lt Green/Yellow (as @2011Supercab called it, too).

That's one vote that matches my cheat sheet...

Since we have the guy all solved now, I got to ask - having looked at the schematic and studied which side of the rheo wiper which wire is on, can you explain why the dimmer is both a full power and a variable? (pins 4 & 5)

I ask because my cheap chinese radio doesn't dim right, and it has only one connection for dim, pin 5 is not hooked up at all.

 

[TonyLittell]

I want to thank everyone for the help. I’ll post up again possibly tomorrow but definitely by Monday.
Hopefully now vehicle fire pictures! Hahaha

thanks again everyone!!!!!

 

[RobbieD]

I ask because my cheap chinese radio doesn't dim right, and it has only one connection for dim, pin 5 is not hooked up at all.

There is a rheostated illumination circuit for the radio backlighting; these lights will dim with the other dash lights. The digital display in the radio uses a second illumination wire, non-rheostated, so that the display will dim when the lights are on. If the rheostated circuit is used for this function, the display would not dim if the instrument panel lights are turned down low.

I'd need to get into one of my trucks, to meter it, but according to the schematic the Orange/Black wire has ACC voltage until the lights are turned on to "Park" or "Head". It's just been too long ago for me to remember how the OEM display dim circuit works. Most aftermarket head units will dim the display (not the backlighting) when an input wire has +12 volts. If your radio has such a wire, try connecting it to the Brown parking light wire in the truck.

 

[Brain75]

Actually your description (and my memory of what the voltages were) explains it...
with headlights off, illumination (BL/PK) has zero volts,
with headlights on + dimmed at lowest brightness, I have ~2 volts on BL/PK
with headlights on + dimmed at highest brightness, I have 11.6 volts on BL/PK
when you "park" the headlight switch (turn it past full brightness to dome light on), I have zero volts on BL/PK

My chinese radio is full brightness as long as there is zero volts on BL/PK, but works inverse and gets dimmer the brighter the dash is.

I now understand this is a backwards reverse behavior issue with the cheap radio now - flaw in the radio design.

Thankfully my radio has 2 brightness memories and is user configurable (it has brightness buttons on the display).. so as long as I leave my dim at a certain place it is tolerable.

 

[RobbieD]

Funny story from "back in the day".

The Ford dealer I worked at, also had a Chrysler/Dodge/Jeep/Renault dealership next door. This dealership group ordered everything without radios. When the first Renault 18i's came in, in two of them I put in Clarion hi-power (80 watt) tape decks. Being a completely new model, both of these cars sold quickly.

Soon one came back, with a customer complaint that the dash lights would dim with the music when the radio was turned up. I thought "Yeah, right", but damned if it did just the customer said. All of the dash lights dimming and brightening with the music was QUITE pronounced. When I had doped out the wiring originally when I did the installs (factory schematics hadn't arrived yet), what I thought was a chassis-ground wire actually was the rheostated illumination ground wire. The radio was grounding along with the lights through the rheostat. Easy fix, the customer went away happy.

I kept an eye out, and clued in the service writers, that I needed to correct that second 18i.

And one day, lo and behold, it pulled into the service aisle. I went to talk to the owner; a kid, about my age, had bought the car. I explained that I needed to change a wiring connection, to correct the dash light dimming with the radio issue.

The kid said "HELL NO!. That's what I like the best about this car. When I rock out, the car rocks out too."

So, I just left it the way it was. And that customer also went away happy.

 

[TonyLittell]

No Smoke or Fires! Thanks for all the help guys!