Can anyone help me with splicing factory harness to after market radio harness?


Asked by Shawn Dec 30, 2014 at 10:07 PM about the 2002 Pontiac Grand Am GT

Question type: Car Customization

I am trying to splice my car radio harness to my aftermarket harness. I understand and spliced the speaker wires together. But i am not sure about the miscelaneous wires. I know for the pioneer radio i am installing the connector diagram is

Constant = Yellow
Ignition = Red
Ground = Black
Power Antenna = Blue
Remote amp = Blue and white

factory diagram

Constant  = Orange
Ground =  Black
Ground 2 = Black/white
Gray = Instrument panel supply voltage
Purple = Gain control signal
Brown = Park lamp supply voltage
Dark Green  = Amplifier control

What do I connect to switched voltage/ignition? and where does amplifier control, gain control, ground 2 and instrument panel get connected to?

11 Answers


All you need is a cheap 12 volt Test light....You can get one from Walmart for about 5 bucks....Ground the test light clamp to something that is grounded in your vehicle...One of the ground wires on your factory wiring diagram should work. If your not sure how to use a test light just hook it to your negative battery cable and touch the positive...It should light up... Then poke the wires with the key off till you find the wire that lights up the test light....That wire is your constant hot wire.....Then turn your key on Auxiliary or the run position till you find the other hot wire that comes on with the ignition turned on....Turn the key on and off...The test light should light up and go dead...That is your ignition wire....You can also use that same wire as your Remote for your amplifier. If your factory radio does not have an ignition on off wire you can run it to a switch source such as a Fuse that is controlled when you turn the key on and off. Use the test light or a fuse tester that has a light built in to test which fuse is a switched ignition source. Then just connect the ground wire to a good ground. That wire does not have to be factory grounded...Some factory ground wires are not that good...

12 people found this helpful.
Best Answer Mark helpful

Here's a wiring diagram for your car. Your existing stereo should have a constant and ignition power wire that you hook the new system to.

7 people found this helpful.

No such thing as plug and play for wiring harnesses. You still need to hook up specific wires from your car's wiring system to the specific wires on your chosen stereo unit.

5 people found this helpful.

Based on the wire diagram user ytlas sent me can anyone tell me where I should connect the dimmer wire, illumination wire and the amp trigger wire ? Thank you. I go to school for automotive and have been in electrical so I figured why not just cut off the connector and splice it to the new one. I didn't realize the wires would be different. Instead of having to run a wire through a gromet in the firewall to my fusebox is there an easier way ? Or a possibility of connecting another switched component ? Another thing, if there's an adapter, how does it supply switched power to the radio without having to wire an additional wire to the fusebox ? Is there a way to just keep the radio on hot all the time without the battery draining overnight or for long periods of time?

7 people found this helpful.

Your existing set up most likely had a constant and ignition power source if your stereo had a built in clock. I'd say you take the factory diagram and start subtracting wires until you isolate which wire of your exisitng set up is the ignition power. That one you hook to the red on the Pioneer.

1 people found this helpful.

I am not an expert on your vehicle but I have hooked up a few dozen car stereos in my lifetime. Some factory wires will not be needed to install an aftermarket head set. Splice the wires needed, then cap off the rest with some wire nuts. OR, you will need to either purchase a vehicle specific wiring harness adapter to plug into your existing cars harness to mate up to the aftermarket headset. is the sight I use to purchase or research all my electronic needs usually. They have a great database and the tech support are very helpful. By your last post the only wires needed are the ground, constant hot, and the Ignition on-off power wires. Those three wires will have the headset operating. If you have a aftermarket amplifier or factory amplifier for your subs, door speakers, or tweeters you can run the remote wire from your amplifiers to the ignition on-off wire or the Remote amp = Blue and white wire on your first post. Although, I would use a test light and confirm the correct wires before making any decisions of my own...Good luck.

3 people found this helpful.

need help no sound after radio install on 2001 grand am. everything seems to work but the sound any ideas..

17 people found this helpful.

Im puting in a J.V.C car radio after math and on the J.V.C RADIO has 14wires and the radio that came with the car has 18wires on i have a 2002pontiac grandam

4 people found this helpful.

They make a wire harness adapter for every car i do a lot of car stereo instalations and swear by them go to and you can find one then all you have to do is wire that to your after market stereo and plug it into your factory wire harness

5 people found this helpful.

Key won’t start car. You can jump starter to starter

1 people found this helpful.

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