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After market radio wiring question

Old Jul 3, 2025 | 08:19 PM
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Default After market radio wiring question

After studying this thread it recommended the following part # for a wiring harness: METRA 70-1858 (first photo)

https://blazerforum.com/forum/audio-...l-parts-11284/



However it does not seem to have all the pins that are on my stock radio. (second photo)





It appears to have the correct mating slots however. So at a quandary here. Anyone have a correct part # for a pigtail with all the pins and correct configuration of the mating slots in the plastic connector itself. (I have noticed pigtails that were said to fit the GM radios but it appears the connectors have different connection slots for mating the male and female.

And the in dash harness has wires in all four quadrants. (next 2 photos)






Need I just cut the in dash connector and wire direct?





 
Old Jul 4, 2025 | 03:14 AM
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If I remember correctly, the quadrant left out of the aftermarket harness connector is used for the factory CD changer and/or tape deck which are often not compatible with aftermarket headunits.
 
Old Jul 4, 2025 | 10:02 AM
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To add to Swartlkk's answer, some of the wires in the factory radio harness are not needed for an aftermarket radio. In addition to controlling remote units like a remote CD or Cassette player, they will provide additional functions such as vehicle speed sensor (factory radio increases volume based on vehicle speed) and a secondary illumination circuit that are not needed/used by most aftermarket head units.

The Metra kit you posted is the correct adapter for your vehicle.

Most units only need +12v constant, +12v switched (ignition), -12v Ground, and 8 speaker wires (+/- for each channel). From there some may also use an illumination/dimmer wire to dim the display when the headlights are on, and most will have a remote turn-on wire to switch on an amplifier but unless you're adding an additional amplifier this won't be used.

The12Volt.com is a great resource for automotive wiring help.
 

Last edited by El_Beautor; Jul 4, 2025 at 10:05 AM.
Old Jul 4, 2025 | 05:17 PM
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Thanks for the clarification. Unit ordered...
 
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