Trying to make sense of this wiring diagram

vegiguy · Mar 8, 2021

I made a post the other week about the stereo wiring layout for the 71-74 B-bodies and someone posted this shop manual page:

. On the "stereo wiring" diagram are the "X54A-20BK" wire and the wire coming out of the molex connector connected to the "X53-20BK" wire loop going to both be body grounds since they are black wires? If so what would they ground to on the body? The wire lines go off of the right side of the page so I don't know where they go to.

Thanks in advance for any clarification.

72RoadrunnerGTX · Mar 8, 2021

On any Mopar from this era, never assume black wires are grounds. There are several circuits using black wires in these cars that are far from grounds. In this case the wires you are inquiring about would more accurately be described as “speaker commons”, are not grounded to the body in the body harnesses. The fold in the page hides that the one wire is routing back up to the top of the diagram labeled as “X54-20BK”.

70chall440 · Mar 8, 2021

X54 = identifies the circuit or purpose (basically allows you to find the wire anywhere it runs in the harness)
20 = 20 gauge wire
BK = black

As noted, the color has no bearing on the purpose or termination; red does not mean hot just like black does not mean ground. You have to follow the wire throughout the diagram to determine where it goes and what it does.

vegiguy · Mar 9, 2021

You're right about black wires on Mopars not necessarily being grounds. The large black wire coming off of the alternator on them is DEFINITELY not a ground.

Nacho-RT74 · Mar 9, 2021

Speakers sends are senoidal signals ( alternate current ) but tipically are labelled as a + and - like direct current. Black would be - which is actually like the neutral in AC

BeepBeepRR · Mar 9, 2021

I just did this maybe it will help. Kind of crude but it should help you make sense of the setup.

Trying to make sense of this wiring diagram

vegiguy

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72RoadrunnerGTX

FBBO Gold Member

70chall440

Well-Known Member

vegiguy

Well-Known Member

Nacho-RT74

Well-Known Member

BeepBeepRR

Well-Known Member

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