wiring woes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69ride · 04-20-2004, 09:22 PM

what type of "fusible link" do i need in line to my alternator from my ignition switch. there is supposed to be a fusible link between my ignition switch and my starter also. The engine is out of a mid 80's chev truck and has the internal regulator I think. When I took the wiring off the truck it was hacked into a million times by the PO and there are some wires that got to hot(melted). I eliminated about 20 feet of wire that went nowhere. and I am going to put my cab back on the frame tomorrow night and hope to start it up by the end of the week-end. But I have these questions about these fuses. I read about the fusible links in my haynes manual, in the wiring schematic. What does it mean exactly? I'm a mechanic by trade so give it to me straight

dubie · 04-20-2004, 09:36 PM

Well ya know I can't help ya there bud,s eeing how we are in the same boat. You running HEI on that engine or is it still points?

dubie · 04-20-2004, 09:42 PM

maybe this will help??
http://www.madelectrical.com/electri...evymain1.shtml

69ride · 04-20-2004, 09:42 PM

hei. I hate the big ugly cap

69ride · 04-20-2004, 10:48 PM

that's a pretty good site dubie but it doesn't explain what a fusible link is and if i need one.

*Slams_58* · 04-20-2004, 11:01 PM

He's planning on going over to Steve Wilson's to check out the wiring on his Longhorn. Maybe he can find out there? I don't know...I have NFC what the heck your'e talkign about anyway!

Jeepster376 · 04-20-2004, 11:23 PM

It's a short length of smaller guage wire spliced into the run. A peice to melt first if there's a problem

Jeepster376 · 04-20-2004, 11:28 PM

madelectrical shows a 16 gauge fusible link, on a 12 gauge run to the ignition circuit.

Sweet72 · 04-21-2004, 02:33 AM

Fusible links are available at most auto parts stores and as Jeepster376 says they are used for circuit protection in the same way a fuse or circuit breaker is. They have a terminal lug crimped to one end and terminate at a junction block. I've seen inline fuses used on our trucks to replace the fusible links, but you must know the current requirement of the circuit. Best to replace them with the same gauge fusible link as shown in your haynes manual wiring diagrams (hopefully yours has them).

GMC Jim · 04-21-2004, 05:55 AM

a fusible link is a short piece of wire 4 guages smaller than the wire the link protects...

**JIMs70GMC** · 04-21-2004, 06:10 AM

Check with the vendors I believe wiring harnesses are available for our trucks w/ an internally regulated alt. and HEI.

bigskiohio · 04-21-2004, 09:06 AM

go to napa and buy links alot cheaper.

BobbyK · 04-21-2004, 12:54 PM

Fusable link won't "blow" like glass or blade type fuses.
They can take a short in the system for a small amount of time.

An example is if you ground a power wire that has a blade or glass fuse it would immediatley "blow".

A fusable link will take that short for a short time.The link will eventually get hot enough and burn up(you'll know it by the tell tale smoke) if the short continues.

If you read the MAD Electrical site it does give a definition of the fusable link and it's advantages in more depth.

I know there is a wealth of electrical info on that site.
http://www.madelectrical.com/catalog/fusible-link.shtml

69ride · 04-21-2004, 05:42 PM

thanks for the info guys, I wasn't going to install the links but maybe i will now.

04-20-2004, 09:22 PM	#1
69ride All Go, No Show Join Date: Jul 2003 Location: Creighton SK Posts: 286	wiring woes what type of "fusible link" do i need in line to my alternator from my ignition switch. there is supposed to be a fusible link between my ignition switch and my starter also. The engine is out of a mid 80's chev truck and has the internal regulator I think. When I took the wiring off the truck it was hacked into a million times by the PO and there are some wires that got to hot(melted). I eliminated about 20 feet of wire that went nowhere. and I am going to put my cab back on the frame tomorrow night and hope to start it up by the end of the week-end. But I have these questions about these fuses. I read about the fusible links in my haynes manual, in the wiring schematic. What does it mean exactly? I'm a mechanic by trade so give it to me straight __________________ 69 LWB Rebuilt 283, aluminum intake, edelbrock carb, Mild Melling Cam, HEI.

04-20-2004, 09:36 PM	#2
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	Well ya know I can't help ya there bud,s eeing how we are in the same boat. You running HEI on that engine or is it still points? __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

04-20-2004, 09:42 PM	#3
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	maybe this will help?? http://www.madelectrical.com/electri...evymain1.shtml __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

04-20-2004, 09:42 PM	#4
69ride All Go, No Show Join Date: Jul 2003 Location: Creighton SK Posts: 286	hei. I hate the big ugly cap __________________ 69 LWB Rebuilt 283, aluminum intake, edelbrock carb, Mild Melling Cam, HEI.

04-20-2004, 10:48 PM	#5
69ride All Go, No Show Join Date: Jul 2003 Location: Creighton SK Posts: 286	that's a pretty good site dubie but it doesn't explain what a fusible link is and if i need one. __________________ 69 LWB Rebuilt 283, aluminum intake, edelbrock carb, Mild Melling Cam, HEI.

04-20-2004, 11:01 PM	#6
Slams_58 Account Suspended Join Date: May 2002 Location: I let ya know as soon as I know Posts: 3,593	He's planning on going over to Steve Wilson's to check out the wiring on his Longhorn. Maybe he can find out there? I don't know...I have NFC what the heck your'e talkign about anyway!

04-20-2004, 11:23 PM	#7
Jeepster376 Registered User Join Date: Feb 2004 Location: Massachusetts Posts: 269	It's a short length of smaller guage wire spliced into the run. A peice to melt first if there's a problem __________________ 72 Cheyenne Super 4x4 SWB

04-20-2004, 11:28 PM	#8
Jeepster376 Registered User Join Date: Feb 2004 Location: Massachusetts Posts: 269	madelectrical shows a 16 gauge fusible link, on a 12 gauge run to the ignition circuit. __________________ 72 Cheyenne Super 4x4 SWB

04-21-2004, 02:33 AM	#9
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	Fusible links are available at most auto parts stores and as Jeepster376 says they are used for circuit protection in the same way a fuse or circuit breaker is. They have a terminal lug crimped to one end and terminate at a junction block. I've seen inline fuses used on our trucks to replace the fusible links, but you must know the current requirement of the circuit. Best to replace them with the same gauge fusible link as shown in your haynes manual wiring diagrams (hopefully yours has them). __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.

04-21-2004, 05:55 AM	#10
GMC Jim Senior Member Join Date: Dec 2002 Location: Portland, Oregon Posts: 901	a fusible link is a short piece of wire 4 guages smaller than the wire the link protects... __________________ '71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal).

04-21-2004, 06:10 AM	#11
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Check with the vendors I believe wiring harnesses are available for our trucks w/ an internally regulated alt. and HEI. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

04-21-2004, 09:06 AM	#12
bigskiohio Registered User Join Date: Sep 2003 Location: Ohio Posts: 127	go to napa and buy links alot cheaper.

04-21-2004, 12:54 PM	#13
BobbyK Registered User Join Date: May 2000 Location: Petrolia,Ontario,Canada but working in Port Huron,Mi. Posts: 1,771	Fusable link won't "blow" like glass or blade type fuses. They can take a short in the system for a small amount of time. An example is if you ground a power wire that has a blade or glass fuse it would immediatley "blow". A fusable link will take that short for a short time.The link will eventually get hot enough and burn up(you'll know it by the tell tale smoke) if the short continues. If you read the MAD Electrical site it does give a definition of the fusable link and it's advantages in more depth. I know there is a wealth of electrical info on that site. http://www.madelectrical.com/catalog/fusible-link.shtml __________________ 71 blazer,350SBC,approx.375HP,700R4,factory GM TPI.Dual electric fans,33x12.5x15 ATR on stock suspension. Petrolia,Ontario,Canada but working in Port Huron,MI. See ALL my Blazer pic's HERE

04-21-2004, 05:42 PM	#14
69ride All Go, No Show Join Date: Jul 2003 Location: Creighton SK Posts: 286	thanks for the info guys, I wasn't going to install the links but maybe i will now. __________________ 69 LWB Rebuilt 283, aluminum intake, edelbrock carb, Mild Melling Cam, HEI.



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