Hello,
I removed the aftermarket radio/cd that was installed in my 1991 coupe tpi. It was working but I like how the car looks with the stock radio that completes the cockpit perfectly imo and I don’t usually listen to anything other than the music the engine makes so I’ve installed a bose radio control head.
The problem is the display doesn’t turn on when I turn the power ****. I can hear a relay click under the dash not sure if it’s the radio.
I bought the RCH but the guy that sold it to me didn’t know if it was working or not so it’s harder to find the problem.
The receiver box is in place, I’ve plugged in all the connectors except for the antenna (for that I would need to remove the receiver I think).
The Receiver “ignition in” wire gets 12V, the battery cable has 12V as well. I’ll try to check the “ignition out” next.
Fuses are good.
The “eject” activates the motor
when I turn on the lights all buttons get lit, but the buttons state leds don’t. I’ll also have to test the outputs to the amplifiers. btw there are no amplifiers and the speakers are not stock but if I managed to make the modules work it should be easy to install amplifiers.
any other suggestions?
thank you.

 

Hopefully I'm not misinterpreting what you are stating, but do you have a CDM in the rear compartment behind the passenger seat and is it plugged in? The Bose system will not work with the head unit alone, you must have the CDM. Then the CDM hooks to an amplifier at each speaker enclosure. My bose head was DOA when I got the car but it literally was just the fuse, so double check those.

EDIT: I see you stated you checked fuses, and I am assuming receiver box = CDM so you DO have one of those (but known working?).

You are going to go through a lot of headache and $$$ to try and get this working 100%, especially if you don't have a working CDM already and known good amplifiers...what are you doing about speakers? And perhaps the HU is bad?

I am personally going in the opposite direction. I initially felt the same as you, but being able to have full integrated bluetooth and ability to have nav if I want it is a big plus. Fumbling with a phone while driving a 6 spd is a pain especially with the limited space in the center console. The bluetooth FM adapter I was using was not great quality (particularly microphone for calls).

What did your aftermarket radio look like? Was it single or double din? I am installing this (but leaving all wiring and the stock amps/speakers) and I expect it to blend in fairly seamlessly with the interior (no buttons, kind of like the DIC area above it).
https://www.crutchfield.com/p_130DM2...H-2660NEX.html

If you aren't happy with how the old aftermarket one looked, switching to a different aftermarket may save you money and headaches...

Just my 2 cents!

 

the aftermarket is a sony xplod cd/mp3
I assume the cdm is the radio receiver box, I have this one present in the car. here are the connectors before plugging them into the unit.

 

I'm pretty sure the CDM is under the dash on the 91. They didn't put it in the storage box behind the passenger seat until 1992. However; you are right
the radio will not work without the CDM.

 

You are correct. It's under the passenger of the dash in 91.

 

Whoops, I forgot that! Not as easy to get to (I have a 93)!


Yes radio receiver box that is separate from the head unit is also called the CDM. That sony headunit would definitely stick out like a sore thumb! If everything is wired and you definitely have power to everything, then you will have to dig deeper...

I saw your post on this thread:
https://www.corvetteforum.com/forums...-question.html

Stinks that a PO hacked up the wiring instead of going with a wiring harness adapter (which is what I'm doing)!

Do you have the FSM? In the electrical diagnostics section (8A-150-8 for a 93), it covers troubleshooting the BOSE system and what to check...

 

Hi
The connectors were plugged by looking at these pictures:

I’ve removed the large white adapter then plugged it into the CDM the black power connectors so it should have power.

I’ve also ordered the FSM and when I get it I’ll check the troubleshooting section
thank you

With the head unit removed and ignition on, I’ve checked the “ignition in” and “ground in” on the large black connector that plugs into the head unit but they were both opened . maybe the cdm needs feedback from the head unit before enabling them. Anyway I will check this directly at the cdm with the head unit connected, ignition on and volume **** turned to the right

 

update:
cdm grey connector with the cable pulled out: the pink wire pin doesn’t have any voltage whether ignition is on or off and the cdm doesn’t connect the black wire pin to the ground either. Anyway with the connector plugged in now the clock turns (no display backlight)on although only for a few seconds after pushing the volume **** and the buttons black light works including the dimming function with the lights on regardless of the ignition switch position. However, with the connector unplugged there is nothing, no clock no buttons backlight.. Basically it doesn’t react to ignition but there is some kind of signal, maybe the green wire does that. I’ll now wait for the FSM to see what else I can do or in the meanwhile I could check what happens if I connect the green wire only.

 

In your bottom picture all the wires in the black connector and the gray connector go to a black connector that plugs into the head unit, with the exception of the shield ground. If you have an ohm meter check that the wires from the CDM have continuity to the connector at the head unit. Someone had worked on my wires and got the two purple wires switched causing my CD to not play. It's unusual for GM to use the same color wire on two wires in the same connector but they did on this connector.

 

thanks for the advice. At some point I wanted to do that but I couldn’t match the schematics with the colors on the real plugs then figured the power wires and tested them. I’ll just test all combinations, for each wire at the cdm (connector you mentioned) there should be one at the head unit.

 

Hello Nilak!

Once you have your FSM you will see the schematic for the wiring of the stereo. In the Electrical book of the two book (FSM) set they had color wiring diagrams. The FSM will be the answer to most of your Corvette needs. If it is going to be a while before you get it someone might copy the pages out of the manual and post them for you. I have the 1988 version but since my dash is a different style the radio wires might not be the same colors.

A few years we replaced the entire stereo from our C4 and put in a modern system from Crutchfield's. I pulled the original speakers which have the little amplifiers on them and replaced them with better speakers and I was able to use the original wiring harness and had to run no new wires. Since each of the four speakers has four wires dedicated to it I just disconnected the power wires and used the speaker wires. My new radio lets me answer the phone while driving and be okay being hands free. I made my own wiring harness with the help of Crutchfield's Support Staff.

The one thing I have learned is that if you start using to a bigger amplifier the sounds get really strange inside the fishbowl interior of the C4.. It would be hard to use a Big amp inside a C4 Coupe as the sound bounces all around the insides of the Coupe.

I hope that all is well for you my friend!

Chris

 

Hello Cris,
Thank you for the advice. I don’t listen to music while driving, especially in this car. The car had an aftermarket audio installed, sony xploid with alpine speakers wired directly from the cdm with like 10Awg wires. I only turned it on once, when I bought the car to see if it was working. Anyway it’s better to have the radio functional of course. If the wiring harness good I’ll remove the cdm and do an inspection of the components.

All the best!