All my lights went out

[85Highsierra15]

I have a 1985 c10 all my lights went out and no power to gauges, truck does start right up, I think it's a ground issue but can't find any bad grounds. Any ideas guys?

 

[chengny]

I have a 1985 c10 all my lights went out and no power to gauges, truck does start right up, I think it's a ground issue but can't find any bad grounds. Any ideas guys?

I would normally say that you lost a fusible link. The headlight switch is fed/protected only by a fusible link. Unfortunately, it's one of the two that connect to the starter solenoid - not the one up high on the firewall.

But what gives me pause, is that your gauges are not functioning. And they are ignition switched and the ignition switch is protected by the fusible link located on the firewall. It doesn't make sense - unless, when you say you have no power to your gauges - you mean that there is no power to the instrument lighting circuit.

 

[jaydee6634]

I would normally say that you lost a fusible link. The headlight switch is fed/protected only by a fusible link. Unfortunately, it's one of the two that connect to the starter solenoid - not the one up high on the firewall.

But what gives me pause, is that your gauges are not functioning. And they are ignition switched and the ignition switch is protected by the fusible link located on the firewall. It doesn't make sense - unless, when you say you have no power to your gauges - you mean that there is no power to the instrument lighting circuit.

Do you know what kind of wire and fusible link is needed that comes off the solenoid? I believe mine is burnt out from being to close/ touching headers. I have the same issue as 85 high minus the gauges not working, mine do, the dash light just doesn't come on with the headlight switch. I have tested the hot wire coming to my headlight switch and there is nothing. I do have turn signals front and back.

 

[chengny]

Do you know what kind of wire and fusible link is needed that comes off the solenoid? I believe mine is burnt out from being to close/ touching headers. I have the same issue as 85 high minus the gauges not working, mine do, the dash light just doesn't come on with the headlight switch. I have tested the hot wire coming to my headlight switch and there is nothing. I do have turn signals front and back.

Yeah, that all makes sense. And, since power to the line side of the T/L CTSY fuse is supplied by the same single fusible link - in addition to the exterior lighting/courtesy and panel lights being out, you should also not have:

1. Horn

2. Cigarette lighter

3. Dome light

4. Cluster mounted clock - if installed

The panel, courtesy & dome/cargo lighting will all come back when you renew the link.

Now to your actual question - refer to the dwgs below:

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A fusible link is nothing more than a wire that is at least 4 gauge sizes smaller than the circuit it protects. However, it's covered with a special insulation that is designed to swell up when the copper conductor inside it becomes overheated. It doesn't necessarily have to be burned completely to cause the insulation to distort.

GM sizes wire using the metric standard (IDK why). According to the dwgs above, the particular fusible link that feeds the circuits in this case is classed as 1 square millimeter in cross-sectional diameter. That area is not exactly - but very close to - the cross sectional area of a #16 AWG conductor. That AWG rating is embossed on a plastic ring - it should be still be visible. If not you'll have to trust me.

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They are always on the shelf at any autoparts store. Here is one from O'reilly's that lists for $4.49:

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Here is the standard repair procedure - nothing more than making two butt splices in your case:

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[jaydee6634]

@chengny thank you for the help. I got it all wired back up last night and everything is working as it should.

 

[jwgreen]

So I was wanting to replace the fusible links with a maxi fuse. How would I figure out what fuse size I would need? Also seeing as how there are multiple fusible links would I need multiple maxi fuses?? Or could I combine some or all of them into one or two? 84 3/4T V8

 

[MrMarty51]

So I was wanting to replace the fusible links with a maxi fuse. How would I figure out what fuse size I would need? Also seeing as how there are multiple fusible links would I need multiple maxi fuses?? Or could I combine some or all of them into one or two? 84 3/4T V8

It will not work, unless someone has come out with a slow burn fuse.
I tried this once upon a time, without success, the fuse just burns out too fast.

 

[jwgreen]

It will not work, unless someone has come out with a slow burn fuse.
I tried this once upon a time, without success, the fuse just burns out too fast.

Did you use a blade fuse or a maxi fuse? My understanding is that a blade fuse will not work but a maxi fuse will.

 

[jwgreen]

Sorry I mistyped that. I meant to say Mega Fuse, not Maxi Fuse

 

[Honky Kong jr]

What about a circuit breaker? And fuse it between the breaker and power source.

 

[jwgreen]

So after much research this is what I have come up with.
They do make a "Slow Blow" fuse in a Jcase style. They sell the holders in a couple styles but I think the inline will work for my application. I have determined that the wire size for the circuits I want to replace Fusible links in are 12 & 10 awg. The ampacity of those wires are 40 & 50 amps respectively. The Fusible Links are roughly 14 & 16 awg respectively which is about 4 sizes smaller than the circuit wire. So my deduction is that the Fusible links must be rated at about those amps. The wiring diagram shows 3 Fusible links, 2 12awg and 1 10awg. So my plan is to replace those links with the corresponding Jcase Slow Blow fuses. If you read about the Jcase fuses they say they are designed to replace Fusible Links. Here are a couple links to the info and products I plan to use. If anyone sees a flaw in my research or execution please let me know.
https://www.waytekwire.com/item/46150/Littelfuse-FHJC1002G-Inline-JCASE-Fuse-Holder/

https://www.delcity.net/store/JCase...MI_8f-7eSZ1wIVxVt-Ch3e9giTEAQYASABEgKIUPD_BwE

https://technick.net/guides/electronics/awg_to_metric/

 

[Sublime]

So after much research this is what I have come up with.
They do make a "Slow Blow" fuse in a Jcase style. They sell the holders in a couple styles but I think the inline will work for my application. I have determined that the wire size for the circuits I want to replace Fusible links in are 12 & 10 awg. The ampacity of those wires are 40 & 50 amps respectively. The Fusible Links are roughly 14 & 16 awg respectively which is about 4 sizes smaller than the circuit wire. So my deduction is that the Fusible links must be rated at about those amps. The wiring diagram shows 3 Fusible links, 2 12awg and 1 10awg. So my plan is to replace those links with the corresponding Jcase Slow Blow fuses. If you read about the Jcase fuses they say they are designed to replace Fusible Links. Here are a couple links to the info and products I plan to use. If anyone sees a flaw in my research or execution please let me know.
https://www.waytekwire.com/item/46150/Littelfuse-FHJC1002G-Inline-JCASE-Fuse-Holder/

https://www.delcity.net/store/JCase...MI_8f-7eSZ1wIVxVt-Ch3e9giTEAQYASABEgKIUPD_BwE

https://technick.net/guides/electronics/awg_to_metric/

How did this turn out?

 

[jwgreen]

How did this turn out?

I have installed the fuses but have not gotten it fired up and running yet. I will update you guys when I get it running which should be middle of next month.

 

[jwgreen]

So after much research this is what I have come up with.
They do make a "Slow Blow" fuse in a Jcase style. They sell the holders in a couple styles but I think the inline will work for my application. I have determined that the wire size for the circuits I want to replace Fusible links in are 12 & 10 awg. The ampacity of those wires are 40 & 50 amps respectively. The Fusible Links are roughly 14 & 16 awg respectively which is about 4 sizes smaller than the circuit wire. So my deduction is that the Fusible links must be rated at about those amps. The wiring diagram shows 3 Fusible links, 2 12awg and 1 10awg. So my plan is to replace those links with the corresponding Jcase Slow Blow fuses. If you read about the Jcase fuses they say they are designed to replace Fusible Links. Here are a couple links to the info and products I plan to use. If anyone sees a flaw in my research or execution please let me know.
https://www.waytekwire.com/item/46150/Littelfuse-FHJC1002G-Inline-JCASE-Fuse-Holder/

https://www.delcity.net/store/JCase...MI_8f-7eSZ1wIVxVt-Ch3e9giTEAQYASABEgKIUPD_BwE

https://technick.net/guides/electronics/awg_to_metric/

How did this turn out?

Hey guys just wanted to give an update. I installed the JCase fuses and they have been working great! One did blow but that was because shorted the positive to ground by accident so the fuse did its job. Great this is that they are super easy to replace, just pop the bad one out and put the new one in. Anyway if anyone is looking to replace their fusible links I think this is a great option.

 

[Sublime]

Awesome Thank you