3FE electrical

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ccasteel

ccasteel

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So here I go. Now that I have running cars for every family member that's driving I can dig into the 3FE wiring. I am hoping to pick #tornadoalleycruiser brain extensively. And any one else willing to chime in. This has been a nagging issue for awhile, but when it finally left me stranded the other day and I decided enough babying it. There are certainly issues in addition to the wiring, but I know for certain the wiring needs attention.

First order of business. Would you suggest removing the entire wiring harness or working in situ. I'm leaning towards towards pulling it and troubleshooting on the workbench.

The problems are many:
It loses power between 1800-2200 rpm
It dies at most intersections - especially if I'm running the vintage air unit
Dash lights pulse with the flashing of the turn signals
Actually the rpm's also fluctuate with the flashing of the turn signals
It is burning up fusible links like I eat crunchberries at the breakfast table
 
If you're driving during the day with the lights off and you flip on a turn signal and the dash lights flash, you've got a bad ground junction (cooked junction) on the wiring harness. When you find it, you'll see the problem. Just gotta find it.
 
Charlie, You have said in the past that wiggling wires will temporarily fix the problem. That means you have to check every connection and make sure it is clean and tight. I have a 10 pound soda blaster that you are more than welcome to use if you like. If you spend a half a day or so cleaning every connection you can find you will eliminate the intermittent problems you have, and then if there are others they should be consistent and and much easier to find.
CraigC
 
@Willys43 Did you forget your login again Craig?
 
It says you have only had 3 posts on MUD ever. Stranger Danger!!!
 
I had Woody change my name so nobody would know who I really am, he evidently wiped me out and is making me start all over.
 
Output Shaft said:
If you're driving during the day with the lights off and you flip on a turn signal and the dash lights flash, you've got a bad ground junction (cooked junction) on the wiring harness. When you find it, you'll see the problem. Just gotta find it.
Click to expand...

I should have been more clear. They are only pulsing when they are turned on. For that matter, all my problems are more pronounced when I'm running the lights, the ac or even just the blower for the heater.

Willys43 said:
Charlie, You have said in the past that wiggling wires will temporarily fix the problem. That means you have to check every connection and make sure it is clean and tight. I have a 10 pound soda blaster that you are more than welcome to use if you like. If you spend a half a day or so cleaning every connection you can find you will eliminate the intermittent problems you have, and then if there are others they should be consistent and and much easier to find.
CraigC
Click to expand...

I'm pretty sure the bad connection fixed by wiggling was due to the cheap connectors I was using for my fusible links. I was blowing them so frequently I bought some cheap connectors so I could always have several spares on hand. I might take you up on the soda blaster though. It can't hurt. How messy are those? Because at the moment the shop I work in is still full of my bosses furniture.
 
It's about like throwing a handful of baking soda on the floor. Sweep it , vacumn it or rinse it off, or even use a weed blower. Do it outside on a warm day and forget about it. It takes very little to do what you have to do. It's a good place to start because all of your connection s will be making good contact when your finished. Nothing worse than an intermitant loose connection. You're welcome to it anytime
Craig
 
Fusible links melt north of 40 amps. They're there to protect the wiring harness from melting.

If you're blowing through fusible links, there is a big time short somewhere... as you probably have figured.

Shorts in the wiring harness usually come from either a connector that got fried from too much current, which melts the insulation which causes things to touch that shouldn't, or chafing that has worn through the insulation somewhere, grounding a 12v+ source.
 
I seem to run into these situations regularly on the LBCs (Little British Cars) I restore. My process starts at the fuse blocks then to the front of the harness (whatever you want to call "font"...engine bay to me). I basically unhook all connections one at a time, evaluate each then follow the harness to the next. Eventually I will stumble upon either a bad connection or melted wire/short in the harness in between. If nothing is found during this process, I will then remove the harness section-by-section and bench test until a discrepancy is found. Sometimes I get lucky and find it right away and others, well, it turns into a harness section build.

On Rovers, the main fuse/distribution bock in the engine bay is the offender 99% of the time. With age, they tend to allow voltage to jump between circuits which in-turn faults the BECM prior to fusible link popping. We assume it's due to unseen corrosion or environmental degradation but not really certain. Wait 5 mins and it all seems to work again until a load decides to hop again. Never seems to be anything visible and the accepted fix is to replace the fuse block itself and re-use all existing wiring. Don't know if 80's exhibit this behavior but I'd investigate that as well.
 
I'd rebuild the whole harness one section at a time. Order all the same color and connectors from Coolerman. Disassemble one section of harness and duplicate it wire by wire with the correct new connectors. I'd bet $100 you'll find the problem in the main engine harness so I'd do that one first. You can chase your tail with a bunch of other half-measures or do it once and for all. I rebuilt all the harnesses in my 40 and it wasn't really difficult. I've even got a couple of rolls of the correct silicone harness wrap you can use to finish it off.
If the project sounds too big, you can even order a ready-made harness from him. Just takes more money. Let me know if you need any help.
 
Did the amp meter get bypassed in the conversion? I would start there with the wiring to the alt. I'm kinda busy changing jobs at the moment but if I get let go early I might have some free time. Have u tried a different alternator or checked it for excess charging? Did they wire in a hot with key exciter with charge indicator light?
 
#1MAC I'm headed down that path. The wiring started coming out last night.

#tornadoalleycruiser amp meter was not bypassed. Alternator was pulled out and checked for proper operation at an alternator shop. Not sure if they wired in a hot with key... Not sure how I would check for that. But at this point starting with a fresh harness is the plan. I don't have it completely out yet and I'm already seeing things that make you say What the heck.

I'm planning to pull the PO's aftermarket additions and start with a simple FJ40 harness spliced to the 3FE harness. HID headlights, vintage air, glow in the dark shift knob and any other additions are all being pulled.

100_2497.webp
 
Can I just disconnect the ac hoses? Or, do I need to somehow keep them connected and remove the whole system as a connected unit. It hasn't blown cold for a couple years, so my guess is there is little if any freon in it.
 
Disconnect ac is fine u will need a new drier anyway. Just tape or cap holes. The one difference in the ignition is 3fe has 2 hot with ign on instead of one in fj40. Spend lots of quality time with the wiring schematic. Double check the nss wiring to insure it was bypassed correctly. I changed my fj40 ign switch to the 3fe 6 prong to match up. I might have way over 40 hours at least in my harness. These are the extras

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Po would not have needed a fuel pressure regulator if the regulator and pulsation dampner on the rail work correctly. I used the stock 62 fuel filter and an hoses. Best luck. You are more than welcome to come look. Hope to be unemployed for a week soon with time in the garage.
 
For me, having the same color wire as the factory harness helped keep things straight, but that's not critical. I assume you have the factory shop manuals for both model years of the harnesses you're splicing together?
Let me know if you'd like the harness wrap material and I'll drop it off to you. I also have a pretty slick wire stripper that will save you from getting blisters using a cheap one.
Good luck!
 
Exactly why I have a box of spare wire . Coolerman is a source of color specific wire I used as well. I ran redundant grounds thru the harness back section and usEd weatherpack connecters in most places. Keeping everything matching the fsm wiring harness was a challenge yet rewarding .
 
I'm planning to keep it matching the factory colors. I have some runs currently that are multiple gauges and multiple colors from one end to the other. Seems he had an abundance of red wire on hand. I need to look into these weatherpack connectors. Did you pick up a combo pack or more or less buy them one at a time? Which ones did you most commonly use?

If my ignition is from the original FJ40 and I source one from an FJ62, will it fit right in without modifying the column?
 
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