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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: stpeteblue on August 11, 2021, 12:53:41 pm
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I was preparing to do a simple blinker mod on my dually fender clearance lights until I exposed the wiring in the loom running to each fender.
I expected to find one hot wire and one ground wire. To my surprise, I find two brown wires and one black wire leading to the passenger fender and two brown and two black leading to the driver fender.
What the heck?
Which wires do what?
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Basically they are spliced together. One set provides ground and one provides power...
Look at page 18 here should go straight there, Look at R05 Wideside (dually):
http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_350_89_1989_GM_RV-P_Light_Trucks.pdf#page=18 (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_350_89_1989_GM_RV-P_Light_Trucks.pdf#page=18)
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I just saw this reply.
I am looking at the diagram, and I understand the brown wire is hot and the black is ground, but why does my truck have two ground wires on the left (driver) side and only one ground wire on the right? Without peeling back the split loom all the way, I'm guessing the ground goes up into the left fender and returns back out to crossover to the right side!?
Also, I believe the diagram has a typo. On the L.H. Front Clearance Lamp, it shows both wires to be 9-8 BRN when I believe one of them should be 150-8 BLK. Look at the attached where the red circle is.
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Bear in mind that a schematic diagram is a simplified connection map, not a wire routing map. A few diagrams illustrate in detail where wires physically run throughout a chassis, but many lack that degree of clarity. In addition, the physical routing of some accessory wires may differ between years and even assembly plants, not-to-mention accessories that may be installed after factory at the dealer level. Suffice it to say that you are correct in deciphering that brown is tail/running and black is ground. You are also correct that the circuit 150 ground wire in the diagram is mislabeled as circuit 9, 0.8(mm)2, brown.