Fusible Link Issues

[meanmachine]

fusible link is giving me a hard time. First I thought it was loose wires inside the black post that goes to battery. Thought I might have fixed it but decided  to wiggle wires and truck stopped running. Is it possible fusible wires can go bad?  

 

 Been having this issue for a while. I tried locating one but no dice. 

 

I've seen post about rebuilding it, but not to familiar with wiring.

 

Also anyone know where I can get one that works

[datzenmike]

lol That is the purpose of the fusible link. It's designed to melt if too much current flows through it. It's a slow blow fuse. What makes it special is the Hypalon plastic coating. It's designed to not catch fire if the wire inside melts. The fusuble links protect the power wires to the fuse box, every thing after the fuse box ... is fused. In the case of an accident these power wires could be pinched and grounded causing the wires to light up like a toaster. The fusible link will blow first before this happens.

 

What color is the wire,  black or green? You can replace by color code, each color is a different amperage rating. Cut them to similar length and solder them in place. You may be able to buy a replacement, I don't know.

 

 

I suppose you could put 80 or 40 amp fuses in line.

 

[meanmachine]

Thanks for the response and the color chart.

 

It looks like like I have 2 green and 2 red, 

 

 

[datzenmike]

Could it be a discolored brown?

[meanmachine]

                       Anyone tell me what color these wires are? 

 

Also about moving wires around and truck shutting off. Aren't the fusible wires suppose to do that? 

[Charlie69]

The 84 is 2 red 2 green and no longer available unless you get lucky and find a good one in a junk yard.

 

Here is what I have been doing when my fusible link fails.

 

https://ratsun.net/topic/78760-wiring-issues/?do=findComment&comment=1696325

[datzenmike]

Interesting... the FSM says black 80 and green 40. Red would be 50. Design change.

[meanmachine]

should i change the red back to black?

[Charlie69]

Not all manucturers of fusible link wires use the Nissan color to amp code.  

Edited February 9, 2021 by Charlie69

[datzenmike]

6 hours ago, meanmachine said:

should i change the red back to black?

 

NO. If it's original stick with it.

 

Yes that color code is for Nissan. If you can't match the color match the amp rating

[meanmachine]

OK, 

I pulled on the 2 red wires and they broke. I'm going to research to find the right fusible wire for this application.

 

Thanks for the feedback

[datzenmike]

I have the factory service manual (FSM) for the '84 and no red. Maybe the were replaced and this is another make with the 40 amp rating?

[Zac7803]

A bit off topic, but is the heater on a that cluster of fusible link wires? Mine was working and is not now.

[datzenmike]

All I have are two GREEN and one BLACK fusible links.

 

One of the greens goes too the ignition switch which only passes it on in the ON, ACC and START positions. The White/Red stripe powers the accessory fuses in the fuse box.... radio/cigar lighter and wiper/ fuel pump. The White/Blue stripe power 5 fuses in the on position

 

The other green powers the headlights

 

The black is on all the time and powers the horn and the heater blower motor. Note here that although the heater is powered at all times the ignition must be on to power the heater relay.  If the horn works it's not the black fusible link. If the wiper works there is power to the ignition.

[Charlie69]

2 hours ago, Zac7803 said:

A bit off topic, but is the heater on a that cluster of fusible link wires? Mine was working and is not now.

One of the red fusible links feed power to the heater/AC.

[datzenmike]

The thing is Charlie you need two fusible links to have a running heater fan. One powers the fan. The other goes through the ignition switch to power the relay to turn it on.

[Charlie69]

You are correct Mike.  I am thinking of the red wire from the 20 amp fuse in the fuse block.  The red fusible link powers the AC clutch on the 85/86 trucks.

 

Mike you have a better source of manuals than I do, what if any are the wiring changes for the 180 watt heaters?

Edited February 11, 2021 by Charlie69

[datzenmike]

On 2/8/2021 at 8:46 PM, meanmachine said:

Thanks for the response and the color chart.

 

It looks like like I have 2 green and 2 red, 

 

 

 

Says it's an '84 but maybe built in '84 but is an '85 model??????? If after June '84 it's an '85. The '84 FSM does not show any red fusible links.

 

Blower motor is on a black fusible link on the '84.

[Stoffregen Motorsports]

On 2/9/2021 at 2:24 PM, Charlie69 said:

Not all manucturers of fusible link wires use the Nissan color to amp code.  

Correct.

 

I buy fusible link in 3 foot sections made by a company called Pico - http://www.picowiring.com/new/pdf/Cat-23.pdf

 

You can buy it here - https://www.summitracing.com/search/part-type/fusible-links/product-line/pico-fusible-link-wires

 

As a basic rule, fusible link wire needs to be 4 sizes larger than the wire it protects, so if you are protecting a 10 ga wire, you need 6 ga fusible link. Length matters too and as Mike pointed out, cut the new ones to similar length of the ones you are replacing.

[datzenmike]

Wouldn't the fuse be smaller so it blows and protects the larger gauge wire?

[meanmachine]

I had a electric shop do this set-up for me. They said it will work, but I wanted fusible wire instead of fusses. I'm concerned with wires over heating and over load. (fire?)

 

Let me know what you think also;

 

Green 40 amp AWG 12 gauge

Red    50 amp AWG 10 gauge

Black 80 amp AWG 7 gauge

 

any suggestions will be welcomed

 

Thank You

[datzenmike]

As I mentioned previously, links use a special hypalon plastic coating on the wire that resists burning when the wire melts. Ordinary wire should never be used for this. A fusible link has the advantage of handling a higher current rating than their design for a short period of time unlike a regular fuse. A minor accidental shorting quickly removed will not cause them to blow. They are there to protect the power wires to the fuse box in the event of an accident where the wires are crushed to a ground. A accident is bad enough without an electrical fire.

[meanmachine]

That's what I thought when I seen the set up and information I've been receiving from the forum

 

Thanks for your response datzenmike

[meanmachine]

5 hours ago, meanmachine said:

I had a electric shop do this set-up for me. They said it will work, but I wanted fusible wire instead of fusses. I'm concerned with wires over heating and over load. (fire?)

 

Let me know what you think also;

 

Green 40 amp AWG 12 gauge

Red    50 amp AWG 10 gauge

Black 80 amp AWG 7 gauge

 

any suggestions will be welcomed

 

Thank You

[Stoffregen Motorsports]

9 hours ago, datzenmike said:

Wouldn't the fuse be smaller so it blows and protects the larger gauge wire?

You're right. My bad...

 

So yeah, a 10 ga wire would use a 14 ga fusible link.

Edited February 14, 2021 by Stoffregen Motorsports