Author Topic: Wiring Harness Questions on 1989 V3500  (Read 1221 times)

Offline kjnmontana

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Wiring Harness Questions on 1989 V3500
« on: June 20, 2020, 09:08:49 PM »
Gentlemen, new to the site. Briefly; Iíve an 89 V3500, former wrecker and now snowplow truck, whose wiring (engine bay and cab), is so out of whack that I decided to replace both sides of the firewall wiring. Iíve been reviewing the various companies offering OEM and Street rod products, trying to get smart on how to tackle this.
Iíve carefully removed the existing harnessí in both engine bay and cab, keeping them 90% intact or tagged.
My question(s) is: is it better to purchase the entire kit from someone like Painless, knowing Iíll likely get everything, plus much that I may not need (itís a carbureted big block, no emissions, no a/c, mechanical FP, no per win/locks, etc) or are there companies that can tailor your needs?
Thanks for anyone caring to munch on this cookie.
« Last Edit: June 22, 2020, 09:20:49 AM by bd »
KJ

Online bd

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Re: Wiring Harness Questions on 1989 V3500
« Reply #1 on: June 22, 2020, 09:55:17 AM »
Over the course of ~50 years of commercially repairing highway vehicles I've never needed to replace a complete wiring harness.  I've repaired and modified countless OE harnesses as well as manufactured custom harnesses for cars, light, medium and heavy trucks, fire trucks, ambulances, RVs, buses, coaches, etc.  Unless fire, age or abuse destroyed obsolete OEM connectors, the application correct wire, terminals and tape are still available.  Aftermarket wiring harnesses nearly always need to be adapted or modified to some degree to match the particular circumstances.  Many are incomplete and sold in individual sections that quickly add significant cost.  With that in mind, how out of whack is "out of whack?"
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline kjnmontana

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Re: Wiring Harness Questions on 1989 V3500
« Reply #2 on: June 22, 2020, 02:10:58 PM »
Thanks for the reply BD, when I purchased the truck the previous owner had repurposed it from being a tow truck to a snow plow. In the cab, he had an elaborate lighting and sound setup to control the light bar on the cab, tow lights and then added the plow lights, led running lights. He removed the light bar but left all control wiring to include some flashers and relays that have me scratching my head. In the engine bay, he spliced in the plow lights on the light side of the fuse block, removed the emissions and a/c components and capped the connectors and wired power to plow actuator to the battery side of the fuse block. Much of the wiring is brittle and faded. Also, he bypassed the fuel selector valve and fed directly off of one tank. So, hence my thought to start afresh. The truck sounds like a sh#t show, but is a great short wheel base plow truck.
KJ

Offline kjnmontana

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Re: Wiring Harness Questions on 1989 V3500
« Reply #3 on: July 19, 2020, 05:07:37 PM »
BD, Iíve removed my truckís inoperative a/c engine bay components (I live in Montana, so it was not worth repairing) but kept the wiring harnesses until I can determine which are required for the heater to work. Do you have a thread you could steer me to so I can get educated? Thanks
KJ

Online bd

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Re: Wiring Harness Questions on 1989 V3500
« Reply #4 on: July 19, 2020, 10:35:38 PM »
1989 Wiring Manual pages 49 & 51
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline VileZambonie

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Re: Wiring Harness Questions on 1989 V3500
« Reply #5 on: July 20, 2020, 07:33:39 AM »
Painless makes a nice wiring harness which I have used although you have to reuse some of the connectors or buy them separately if you want all new. Chris sells American Auto Wire on here I believe still but I have never used one so I'm not sure what theirs comes with or if there are any limitations. You can PM him and ask about it. http://store.73-87chevytrucks.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=7&Product_Code=AAW-510706&Category_Code=ELEC
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Offline kjnmontana

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Re: Wiring Harness Questions on 1989 V3500
« Reply #6 on: July 20, 2020, 11:16:47 AM »
Thanks VZ, is the Painless harness youíre referring to this one; 23 Circuit - Pro Series Truck - GM Keyed Column - Bulkhead Firewall Pass-Through P/N 10405?  I did not see mentioned in the installation literature anything about climate control wiring.
KJ

Offline kjnmontana

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Re: Wiring Harness Questions on 1989 V3500
« Reply #7 on: July 20, 2020, 02:25:56 PM »
BD, thank you for the wiring diagram, very helpful.
KJ

Offline kjnmontana

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Re: Wiring Harness Questions on 1989 V3500
« Reply #8 on: July 20, 2020, 09:45:32 PM »
BD, looking the wiring schematic, specifically Section A Page 18, on the engine side fuse block, do you know what fuses numbered 931 and 78 are associated with? I do have the LE8 motor associated with this schematic. Thanks
KJ

Online bd

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Re: Wiring Harness Questions on 1989 V3500
« Reply #9 on: July 20, 2020, 11:05:27 PM »
Both 931 & 78 are circuit numbers, not fuses.  They pass through the firewall bulkhead connector, not the fuse block.  Both belong to the CHOKE lamp warning circuit on the ground side of the lamp.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)