radio wiring question...know these wires? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

dbenamati · 12-10-2002, 06:01 PM

I wanted to know if someone who knows radios can help me with a Delco AM/FM radio question about the wires comming from the radio (it may be from early 70's chevy radio) There are three wires that are not speaker related (yellow, gray and black) can anyone tell me which is the power wire to the radio? My guess is yellow but before I blow the thing up, thought I'd ask. also if I were to test using a 12 V. battery with a fused link, do I have to ground the radio through the housing or is one of the other 2 wires a ground? Thanks, Dave

my new 72 · 12-10-2002, 06:55 PM

Black is ground, red is 12V keyed, and Yellow is 12V constant on the new radios. What year is your radio? The only reason it would have a yellow wire would be to store preset stations, but if it's turn dial I really dont know. But I do know that the red is power, and black is ground.

rusty ol' 69' · 12-10-2002, 07:14 PM

If yellow is constant or light wire. I would guess gray is ign. power or in other words positive. Try hooking it up the ground wire (black) and then use a fused wire w/ 10amp fuse to try both wires the fuse will blow before the radio will. My best guess is from what my new 72 says is the gray is the positive since the other two have just been identified. Just my .02

my new 72 · 12-10-2002, 07:29 PM

Sorry about that. I didn't reread the post very carefully. The gray should be the 12V keyed in your case. Sorry about that.

dbenamati · 12-11-2002, 09:45 AM

Thanks for the info...I'll get out the battery charger and hook it up today to try it out and let you know if it all works...
Black ground wire
Gray 12 V. Keyed
yellow constant.

XXL · 12-11-2002, 02:04 PM

Slow down there everybody... the factory wiring harness of pre-1978 GM is as follows--

yellow = switched 12v
black = ground
gray = illumination (+)

There is no "memory" wire on most of these vehicles (constant 12v), but for those that had it, it was on a separate plug and was orange.

Kenneth

XXL · 12-11-2002, 02:06 PM

BTW, this is the BLACK rectangular plug with the 'key' on one end to prevent mixing it up with the other two plugs (one blue, one white).

Kenneth

dbenamati · 12-11-2002, 05:56 PM

Thanks for the info on the wires...The yellow is the 12 V and the gray works the bulb....another question, what do I hook the gray wire to? If I hook it to the 12 V to get light, the light will be on all the time or as long as the ign is on right?

XXL · 12-11-2002, 08:08 PM

The gray wire is energized when you pull your lights on. So... you'll want to find a wire that's hot when the lights are on. If you look on the back of the light switch on the dash, one of those wires is hot only when the switch is out (both positions-- running and headlights). I don't know the color on our old trucks but on later GM it was light brown or white. Just check for it with a test light.

Kenneth

my new 72 · 12-11-2002, 08:52 PM

He didn't say what year stereo it was for sure. I did say on the newer style radios with preset stations. Sorry if I was wrong in this case, but with the wrong info noone is ever right.

dbenamati · 12-12-2002, 09:36 AM

I'll check that tonight, thanks. This radio is from 1975 Chev. and Its going to be a back up for my AM comming hopefully next week. I tested it last night and works fine (AM/FM). So with all the info you guys gave me, I'm going to clean it up, label all wires with instructions and box it away. As for that gray wire, i was thinking of just splicing into the heater control light, right below to come on with that light. Thanks for all the help, i really appreciated all expertice. Dave

rusty ol' 69' · 12-12-2002, 02:00 PM

Wiring these old trucks is as basic as it gets. Just make sure you got a test light you can't make too many mistakes if you know how to use one. Also the keyed wire should be labeled on the fuse panel as radio with an arrow pointing to the connector. Pretty straight forward.

12-10-2002, 06:01 PM	#1
dbenamati Registered User Join Date: Dec 1999 Location: hughesville, pa usa Posts: 337	radio wiring question...know these wires? I wanted to know if someone who knows radios can help me with a Delco AM/FM radio question about the wires comming from the radio (it may be from early 70's chevy radio) There are three wires that are not speaker related (yellow, gray and black) can anyone tell me which is the power wire to the radio? My guess is yellow but before I blow the thing up, thought I'd ask. also if I were to test using a 12 V. battery with a fused link, do I have to ground the radio through the housing or is one of the other 2 wires a ground? Thanks, Dave __________________ Dave Benamati Hughesville, PA USA

12-10-2002, 06:55 PM	#2
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	Black is ground, red is 12V keyed, and Yellow is 12V constant on the new radios. What year is your radio? The only reason it would have a yellow wire would be to store preset stations, but if it's turn dial I really dont know. But I do know that the red is power, and black is ground. __________________ I'm going to Law School, wanna debate? It's good practice.

12-10-2002, 07:14 PM	#3
rusty ol' 69' Grubbin' Join Date: Aug 2002 Location: Chico, CA Posts: 293	If yellow is constant or light wire. I would guess gray is ign. power or in other words positive. Try hooking it up the ground wire (black) and then use a fused wire w/ 10amp fuse to try both wires the fuse will blow before the radio will. My best guess is from what my new 72 says is the gray is the positive since the other two have just been identified. Just my .02 __________________ project rust attack 1969 Chevrolet LWB w/ 307. I got power steering now woohooooo!!!!!!!

12-10-2002, 07:29 PM	#4
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	Sorry about that. I didn't reread the post very carefully. The gray should be the 12V keyed in your case. Sorry about that. __________________ I'm going to Law School, wanna debate? It's good practice.

12-11-2002, 09:45 AM	#5
dbenamati Registered User Join Date: Dec 1999 Location: hughesville, pa usa Posts: 337	Thanks for the info...I'll get out the battery charger and hook it up today to try it out and let you know if it all works... Black ground wire Gray 12 V. Keyed yellow constant. __________________ Dave Benamati Hughesville, PA USA Last edited by dbenamati; 12-11-2002 at 09:49 AM.

12-11-2002, 02:04 PM	#6
XXL Señor Member Join Date: May 2002 Location: Edge of the world Posts: 5,367	Slow down there everybody... the factory wiring harness of pre-1978 GM is as follows-- yellow = switched 12v black = ground gray = illumination (+) There is no "memory" wire on most of these vehicles (constant 12v), but for those that had it, it was on a separate plug and was orange. Kenneth __________________ Craigslist \| ebay \| Engrishtees \| www.myattitudesucks.com \| Follow me on Twitter

12-11-2002, 02:06 PM	#7
XXL Señor Member Join Date: May 2002 Location: Edge of the world Posts: 5,367	BTW, this is the BLACK rectangular plug with the 'key' on one end to prevent mixing it up with the other two plugs (one blue, one white). Kenneth __________________ Craigslist \| ebay \| Engrishtees \| www.myattitudesucks.com \| Follow me on Twitter

12-11-2002, 05:56 PM	#8
dbenamati Registered User Join Date: Dec 1999 Location: hughesville, pa usa Posts: 337	It works! Thanks for the info on the wires...The yellow is the 12 V and the gray works the bulb....another question, what do I hook the gray wire to? If I hook it to the 12 V to get light, the light will be on all the time or as long as the ign is on right? __________________ Dave Benamati Hughesville, PA USA

12-11-2002, 08:08 PM	#9
XXL Señor Member Join Date: May 2002 Location: Edge of the world Posts: 5,367	The gray wire is energized when you pull your lights on. So... you'll want to find a wire that's hot when the lights are on. If you look on the back of the light switch on the dash, one of those wires is hot only when the switch is out (both positions-- running and headlights). I don't know the color on our old trucks but on later GM it was light brown or white. Just check for it with a test light. Kenneth __________________ Craigslist \| ebay \| Engrishtees \| www.myattitudesucks.com \| Follow me on Twitter

12-11-2002, 08:52 PM	#10
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	He didn't say what year stereo it was for sure. I did say on the newer style radios with preset stations. Sorry if I was wrong in this case, but with the wrong info noone is ever right. __________________ I'm going to Law School, wanna debate? It's good practice.

12-12-2002, 09:36 AM	#11
dbenamati Registered User Join Date: Dec 1999 Location: hughesville, pa usa Posts: 337	I'll check that tonight, thanks. This radio is from 1975 Chev. and Its going to be a back up for my AM comming hopefully next week. I tested it last night and works fine (AM/FM). So with all the info you guys gave me, I'm going to clean it up, label all wires with instructions and box it away. As for that gray wire, i was thinking of just splicing into the heater control light, right below to come on with that light. Thanks for all the help, i really appreciated all expertice. Dave __________________ Dave Benamati Hughesville, PA USA

12-12-2002, 02:00 PM	#12
rusty ol' 69' Grubbin' Join Date: Aug 2002 Location: Chico, CA Posts: 293	Basic wiring Wiring these old trucks is as basic as it gets. Just make sure you got a test light you can't make too many mistakes if you know how to use one. Also the keyed wire should be labeled on the fuse panel as radio with an arrow pointing to the connector. Pretty straight forward. __________________ project rust attack 1969 Chevrolet LWB w/ 307. I got power steering now woohooooo!!!!!!!



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