No start after working on power windows

[tucsonjwt]

I replaced the wiring harness/ connector on my driver's side power window and it worked fine. Two days later I have no start. I have an 83 C20 454 with granny 4 speed manual transmission.

I have dual start batteries with 95% state of charge on both batteries. Battery connections are tight. I have LMC relay upgrade and all of the relays check good with a relay tester.

Before I start poking around aimlessly under the dash I could some guidance. I suspect the clutch safety switch might be an issue, but I hope not since they are no longer available.

I hate working under the dash because I am a big handed 6'2" overweight guy and that fuse box is almost inaccessible for me.

Any tips would be appreciated.

Thanks

[tucsonjwt]

Also, horn, headlights, dome lights all work fine.

[tucsonjwt]

Most of the fuses in the fuse block under the dash have no power. I looked under the hood at the firewall and I saw the fusible link has bare wire showing where it connects to a crimp connector and two other wires. It looks like there was some arcing going on there based on the charred insulation. (See pics.) The insulation on the fusible link looks cracked along it's length.

So, I think I should replace the fusible link. What gauge link do I need? Also, should I put both wires connected to it in one butt splice connector, or is there a two way connector for this application?

Thanks.

[tucsonjwt]

I forgot to attach the pics.

It looks like there is a remnant of a factory style plate with integral eye contact left on the junction box (it has a bare lead left on it where the original fusible link probably went.)

Thanks for looking.

[Dead Parrot]

Normal rule for fusible link is 4 wire gauge sizes smaller(larger number) then the wire being protected. So a 12 gauge wire would get a 16 gauge fusible link. A lot of links are sized in square mm so you might have to find a square mm to wire gauge chart.

Another way is visit a salvage yard and pull a factory link and wire that matches what you need.

Might want to temporarily install one of those single fuse holders. Possible you have a intermittent short in your door repair.

[tucsonjwt]

[QUOTE=Dead Parrot;8910222]Normal rule for fusible link is 4 wire gauge sizes smaller(larger number) then the wire being protected. So a 12 gauge wire would get a 16 gauge fusible link. A lot of links are sized in square mm so you might have to find a square mm to wire gauge chart.

Another way is visit a salvage yard and pull a factory link and wire that matches what you need.

Might want to temporarily install one of those single fuse holders. Possible you have a intermittent short in your door repair.[/QUOTE

I was able to find a faint 14 ga marking on the link so I got one at the parts store with diy eye and splice ends. But the connectors are so cheap and small they slide off the wire rather than crimp down. I found a 14 ga Ford style link in my kit of electrical supplies which has a better eye end installed, but I don’t see how to get 3 big wires into the small blue butt splice connector on the opposite end. It looks like the previous person who worked on it jammed all 3 wires into a 12 ga connector. Does anyone know of a cleaner way to join the link to the 2 large wires on the output side?
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[tucsonjwt]

I know twisting and soldering the wires is the best connection, but as you can see there is no slack on the wires and no room to work, so I think my best shot is to use some kind if crimp connection. Is there a 2 into 1 crimp connector?

There is a good chance that this fusible link problem is not the whole issue, but it does look worthy of replacement. The LMC power window harness had a connector for the switch which did not seat fully against the switch, which exposes about 1/16” of bare contact. I got a bit of arcing when I operated the window, which may have compromised the link. The windows did work and the truck did start for 2 days, so I am scratching my head.

Thanks.
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[tucsonjwt]

How about using Wago lever nuts for the tight space with no wire lead?

[v30crewcab]

skin a short wire on each end, and push it into the back of the clutch safety switch plug, to temporarily bypass it. see it it starts then.

[tucsonjwt]

I was going to jumper wire the clutch switch when I found the questionable fusible link.

I don't like the harness connector I got from LMC. The connector does not fit flush against the back of the switch and I did see some arcing between the contacts when I first installed it, but the switch did work. I think that may have contributed to the fusible link damage. I am going to fit a piece of tool tray liner in between the connector and switch to fill the gap. If that does not work I will have to buy a Delco harness/connector. I installed one on the other door with no fitment issues, but the wires are not color coded like the LMC connector.

[tucsonjwt]

Here is the drawer liner insulator hack

[tucsonjwt]

The truck started after replacing the fusible link. The Wago lever nut was the only way I could connect the wires - it seemed to hold tight. I always use electrical tape over the levers to keep them from coming open during movement. The window would not work with my homemade insulator, so I removed it. The switch only works intermittently. I think there is a weak spot in that LMC switch internally, or it is shorting out internally. I may have to buy the delco replacement harness, but those have very bad reviews.

[Pontiac1976]

Seeing how bad the + wires on the junction box in post4 pic3 I would clean all your + and your -Ground to body area contacts I bet you will see a big improvement batt power your truck.
They sell one of the box store in your area like pet boys wiring fix section a wire to wire connection from one size to another size one name brand standard step down but connectors (maybe STP385 OR STP386 But they sell them a box of 10's and heat shrinkable tube in 7.9 (5/16") x 75mm or 9.5 (3/8")x75mm in red or black make sure on the wire be for you crimp you can use a little bit liquid electric tape on the end after you slide in to place the shrink there it a water tight seal heat gun work best.