Engine Bay Mysteries

[AZ Highlander]

Any help for these loose wires and disconnected relay?

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[85K304SPD]

The red wires look like they were added. A wiring diagram will tell you what the factory wires and the relay are for.

 

[Radiohead]

Is that a choke heater wire from OE? The one with its terminals facing up.

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[AZ Highlander]

The red wires look like they were added. A wiring diagram will tell you what the factory wires and the relay are for.

The red wire going through the firewall is a mystery easy enough for me to solve.
Electric radiator fan is connected via that red wire to a switch by the headlight pull switch

 

[Scott91370]

I do not envy you!! I remember going through all of this 2.5 yrs ago.
I wish I could help and if I find my pics/drawings/diagrams I will share!!

I do have to ask, is this on the 87 in your sig?

 

[AZ Highlander]

I do not envy you!! I remember going through all of this 2.5 yrs ago.
I wish I could help and if I find my pics/drawings/diagrams I will share!!

I do have to ask, is this on the 87 in your sig?

Haha!
Please do share anything you can!
I am horrible at reading wiring diagrams and the PO really started deleting everything to make this a OHV 4x4 that was only functional for off roading.
I'm putting it all back slowly.
Yes, it is the 87 in my signature.

 

[Grit dog]

Start with what doesn’t work?

 

[AZ Highlander]

Start with what doesn’t work?

How about what does work?
It’s a shorter list!

Headlights work, but not tail lights.
Rear turn signals work, but not front.
Wipers and squirters work
Engine starts right up and battery is always charged by alternator just fine.

No horn. No working gauges. No heat or a/c. No radio.

 

[Grit dog]

lol, sorry. Appreciate the humor though.
I’d start by tracing the feeds to the fuse box from the firewall/fusible links.
This is where a wiring diagram would come in handy. That seems like “most” of the issue.
At the same time, I’d verify all, or just throw on some new temp or permanent grounds. Engine to chassis, cab/chassis, bed/chassis and clean up all the lighting system individual grounds.
Hope this helps?

 

[BRetty]

I feel ya'. The second thing I thought when I popped the hood on my '73 C10 (*) was, "what are all these loose wires?" (**)

Have you foud the wiring diagrams here at the site? They are SUPER hard to read. Here's what I did (partially, I haven't done this for all the documents...)

Get or find/use a decent PDF reader/editor, to:
-- Delete all the pages in the manuals that DO NOT pertain to your vehicle. More than half of the pages will be for diesel engines, or vans, or other stuff you don't have. Delete it, it's confusing. Save yourself a copy of the now many-fewer-page PDF.
-- Use an editor or even MS Paint, to draw a colored line over the wire traces so you know what wire is what color.

It would help if you posted a pic of your whole engine bay, here in this thread, so we can see what accessories like A/C etc, are there, or have been removed by PO. For me, a lot of the mystery wires were for:

-- the former A/C unit.
-- TCC (torque converter clutch that was not hooked up)
-- Replacement HEI ignition module made old disrto wires with inline resistor(s) redundant.

Also, the suggestion to add/clean/check your ground wires is crucial. I had my truck just die over and over until I cleaned all the battery cables and added cround wires all around.

Hope this helps,
BRetty

* -- A huge part of the mystery was that my truck has a '73 body and VIN, but the engine, transmission, and entire dashboard from an '81 Suburban. Pulling the dash pad and finding the other VIN there explained a LOT. Make sure you're not looking at the wrong parts.
** -- My first thought wa, "My God look at all the room in here! I could rent this out as an apartment!" Followed by, "What is that thing the fan is clipping...oh it's a CUT-OFF, UNCAPPED FUEL LINE!!!! AAARRRGHHH!!"

 

[AZ Highlander]

I feel ya'. The second thing I thought when I popped the hood on my '73 C10 (*) was, "what are all these loose wires?" (**)

Have you foud the wiring diagrams here at the site? They are SUPER hard to read. Here's what I did (partially, I haven't done this for all the documents...)

Get or find/use a decent PDF reader/editor, to:
-- Delete all the pages in the manuals that DO NOT pertain to your vehicle. More than half of the pages will be for diesel engines, or vans, or other stuff you don't have. Delete it, it's confusing. Save yourself a copy of the now many-fewer-page PDF.
-- Use an editor or even MS Paint, to draw a colored line over the wire traces so you know what wire is what color.

It would help if you posted a pic of your whole engine bay, here in this thread, so we can see what accessories like A/C etc, are there, or have been removed by PO. For me, a lot of the mystery wires were for:

-- the former A/C unit.
-- TCC (torque converter clutch that was not hooked up)
-- Replacement HEI ignition module made old disrto wires with inline resistor(s) redundant.

Also, the suggestion to add/clean/check your ground wires is crucial. I had my truck just die over and over until I cleaned all the battery cables and added cround wires all around.

Hope this helps,
BRetty

* -- A huge part of the mystery was that my truck has a '73 body and VIN, but the engine, transmission, and entire dashboard from an '81 Suburban. Pulling the dash pad and finding the other VIN there explained a LOT. Make sure you're not looking at the wrong parts.
** -- My first thought wa, "My God look at all the room in here! I could rent this out as an apartment!" Followed by, "What is that thing the fan is clipping...oh it's a CUT-OFF, UNCAPPED FUEL LINE!!!! AAARRRGHHH!!"

Thanks! Good ideas here.
Here is the pic of the entire engine bay.

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[Rudy Mienert]

I've been going through similar issues, and I'm a stickler for having everything work as it should. I just ordered a color wiring schematic from ClassicCarWiring.com,...I've used these on other projects, and they sure do make this a bunch easier to solve....By the way, my guess is also start from the engine bay wiring bulkhead into the fusebox..

 

[AZ Highlander]

Looks like Brown (9) is my wire that is pushing power to the tail lights, license plate light, and parking lights.
I checked the sockets and they get good grounds, so I figure it must be that BRN-9 wire(s) that need to be mended somewhere.

@BRetty :
Thanks for the recommendation to "Use an editor or even MS Paint, to draw a colored line over the wire traces so you know what wire is what color."
It helped, even if I don't have the steadiest hand to trace the wires in the wiring diagrams!

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[AZ Highlander]

Well, I hit a speed bump.
I looked at the fuse box and there was a missing fuse for the "T/L CTSY" 20A spot.
I tried the 20A fuse that was in the "WIPER" spot (wipers are funcitonal) in the "T/L CTSY" spot.
*SPARKS*
Blew the fuse.
My circuit tester light is showing that its getting power on one side of the "T/L CTSY" spot, even with the headlights pushed all the way in.

 

[Radiohead]

Sir, you have a short.
Here's where the fun comes in

On edit - this should be an always hot circuit normally