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SpeedCrazy

Car Stereo Wiring Conundrum

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Hey Fellas,

If any of y'all are any good with car stereos, i think some of you are, i could use some advice as i am thoroughly confused. So my buddy gave me an old radio to replace mine that went out back in november(3 months sans radio SUCKS!!) and i wired it up, red wires to red, yellow to yellow and black to black. Nothing, checked all my contacts and my ground, still nothing.

So i called up another buddy who has installed stereos for a number of our friends and asked his advice, his advice worked but has left me confused as it contradicts all i though i knew about electronics.

What he told me to do was take both yellow wires and both red wires and twist them all together, all four! I was under the impression that one set was positive and the other negative... that being the case shouldn't this splice job have left my radio a smoking wreck?

What am i missing here? Does the ground complete the circuit?

 

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Don't twist the wires all together.

Colours don't mean shit on the OEM side of things.

You have little to no hope of identifying the wires on the radio side if its some old OEM thing.

 

In an aftermarket radio you have the following wire colours. (From memory)

 

Black - neutral

Red - accessories or constant

Yellow - accessories or constant (you'll work out which is which quick haha)

Blue/blue with white stripe - antenna and remote

Orange - illumination

Grey and grey with stripe (FL or FR again its been a while)

White? And white with stripe (FL or FR honestly can't remember if its even white haha been too long)

Purple and green pairs for the rear speakers.

 

That's the pretty standard set up.

 

Testing for wire involves the use of a test light and first finding the constant (it connects to the battery directly so you don't loose the memory on the head unit), then accessories (found by switch the key on and off while probing), then you have the neutral/ground however you may find multiple grounds so you may get to watch you Ariel go up and down in the end it becomes lots of common sense to discover what each wire does. Testing the speakers can be achieved with two bits of wires taped to the ends of a AAA battery.

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So if red to red doesn't work i should try red to yellow? All i have are three wires from the dash and three from the radio(not counting speaker wires which are labeled as such) red yellow and black, and i know that the black from the dash i ground as it terminates next to my steering column.

As to old and oem... its a 85 truck and a stock radio out of a 91 truck.

BTW, that site does not have my vehicle, and 85 Nissan 720 ST.

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depending on the Application Red is + Full time...

 

Yellow is the trigger wire or + w/key on....

 

Black is ground

+1 on this, follow this, wire up your speakers and your good to go.

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depending on the Application Red is + Full time...

 

Yellow is the trigger wire or + w/key on....

 

Black is ground

+1 on this, follow this, wire up your speakers and your good to go.

 

Other way round, went and checked and yellow is the 12v constant while the red is the trigger/accessories wire (this is from the headunit side with an aftermarket headunit.)

 

 

You will need to find a way to probe your loom and the best way it with a 12v test light, you could technically dummy one up with two bits of wire and a 12v bulb. That or use a multimeter set to read voltage but its not the most advised thing.

 

You shouldn't just be guessing colours and should be testing wires and if at all possible get into your buddies truck to identify his loom too, if he has had his headunit replaced with an aftermarket one, identification will be all too easy.

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Your best bet is go to Wally World auto dept and pick up a wiring adapter for your make and model of car/truck about $10 and go from there.

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depending on the Application Red is + Full time...

 

Yellow is the trigger wire or + w/key on....

 

Black is ground

+1 on this, follow this, wire up your speakers and your good to go.

 

Other way round, went and checked and yellow is the 12v constant while the red is the trigger/accessories wire (this is from the headunit side with an aftermarket headunit.)

 

 

You will need to find a way to probe your loom and the best way it with a 12v test light, you could technically dummy one up with two bits of wire and a 12v bulb. That or use a multimeter set to read voltage but its not the most advised thing.

 

You shouldn't just be guessing colours and should be testing wires and if at all possible get into your buddies truck to identify his loom too, if he has had his headunit replaced with an aftermarket one, identification will be all too easy.

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Your best bet is go to Wally World auto dept and pick up a wiring adapter for your make and model of car/truck about $10 and go from there.

If an after market headunit was going into it than yes for the inexperienced that would be the easiest way to still do it yourself. As an oem unit is going into the truck it wont go so well.

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It shouldn't be this complicated. I have four wires. Two red, two yellow. If its not red to red should it not be red to yellow?

I don't know what loom is, and the truck the radio came from was wrecked.

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Speed, would be really helpful to know what type of vehicle you are installing into, and also what type of head unit you're installing.  But honestly if it's working ok per the instructions you received from your friend - I'm not sure what the problem is.

 

Nothing wrong with pairing the switched and full time 12v wires together.  The reasons most head units have both a switched and full time;

 

1. Switched wire - so your radio doesn't stay on when the ignition is turned off

2. Full time - to save radio presets and time

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