Why is my stock 92 Radio "Frozen"

[454C2500]

Picked up a 92 GMC SLE and the stock radio is frozen for a lack of a better term. I can turn it on and off but it only shows 1:00. Can't turn up volume or do anything else with it. No sound of course. The tape player/equalizer thing is dark. Am I doing something wrong or is there a fix for this?

 

[AK49BWL]

Chances are your CDM (central "brain" unit) has quit. The electronics are old, it's bound to happen eventually. The only fix is to replace the CDM - it's to the right of the accelerator, mounted to the dash and firewall by three 7mm screws, with three wiring connectors attached. When looking for a replacement, note that they're not all the same - try to match part numbers if possible, but if not, you can refer to this thread for equivalent part numbers for the "5EQ" CDMs. Junkyards or ebay will be about your only options for replacements, and on ebay you can get them with Bluetooth and Aux inputs now.

 

[Erin]

Chances are your CDM (central "brain" unit) has quit. The electronics are old, it's bound to happen eventually. The only fix is to replace the CDM - it's to the right of the accelerator, mounted to the dash and firewall by three 7mm screws, with three wiring connectors attached. When looking for a replacement, note that they're not all the same - try to match part numbers if possible, but if not, you can refer to this thread for equivalent part numbers for the "5EQ" CDMs. Junkyards or ebay will be about your only options for replacements, and on ebay you can get them with Bluetooth and Aux inputs now.

How do you test a cdm to see if it works(while it’s out of the truck)?

 

[AK49BWL]

You'd need a 12v power supply and a spare head (for the display). Not entirely necessary to have speakers attached but it's better if you do so you can test the amp outputs as well. Grab a wiring harness from any 88-2002 truck (S10 or full-size) to plug into them - for the trucks, Orange is Hot at all times, Yellow is Accessory (key-on), black is ground. That'll get you basic power to see if the unit functions at all.

Full pin-out:

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[Erin]

You'd need a 12v power supply and a spare head (for the display). Not entirely necessary to have speakers attached but it's better if you do so you can test the amp outputs as well. Grab a wiring harness from any 88-2002 truck (S10 or full-size) to plug into them - for the trucks, Orange is Hot at all times, Yellow is Accessory (key-on), black is ground. That'll get you basic power to see if the unit functions at all.

Full pin-out:

You must be registered for see images attach

Thanks. I do have the original head unit & tape deck but no wiring harness. I would’ve had them installed back into the truck but couldn’t find them for 3 years. I ended up installing a retrosound. If these still work I’ll sell them.

 

[DerekTheGreat]

What AK49 said. I've had this happen to my truck twice. It was indeed the CDM. Swap that out for a good one, and all will be fine again. It's worth popping the cover off on the prospective CDM. If you see any corrosion on the pins for the main harness where they go into the motherboard- don't buy that one.

 

[454C2500]

I might just scoop a CDM on eBay that matches. I could have mine repaired for $125 which also works. Glad I don't have to install an aftermarket radio or something.

 

[DerekTheGreat]

Or you could look for a CDM from a 1994 or so truck. AK49's thread details which part numbers have increased output. When I was on the hunt for my 2nd replacement, I used that treasure trove to confirm I was pulling one with increased output. Visually they are different enough- larger heatsinks and all that. But they will make a difference if you plan on driving aftermarket speakers with lower impedance than the stock stuff like I did.

I love the stock look as well. My truck originally had some ultra ugly base model Alpine deck in it. Put it on the shelf in favor of the factory tape deck w/equalizer combo. Surprisingly enough, it actually sounds better than the Alpine. I also did the auxiliary input mod, that's worth a look too, if you'd like to hook other stuff up to the radio.

 

[454C2500]

Pulled my CDM and its a 16147065. It is boxed up and going to the rebuilder - he says $125 plus shipping and he is going to rebuild it not just repair it.

Also there was this box which I think may be an FM modulator for syncing a phone? I don't need that if so. Can anyone confirm my suspicion and let me know if I can eliminate that or if its is a factory part.

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[AK49BWL]

That is definitely not factory lol. You should be able to unplug it and remove with no problem.