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Where is the fuseable link in the headlights circuit on 1979 IH 2574

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
554
Location
Etowah Tennessee
Have lost several circuits, this is not a diagnosable by internet problem. Find a mechanic that has electrical troubleshooting skills is your best bet.
That's what I did last week but so far he hasn't touched it. I talked to an old friend of mine that is retired and he told me to start with the switch as well,so I might go get it and try that if the shop doesn't get started soon.
 

mekanik

Senior Member
Joined
Aug 20, 2015
Messages
942
Location
Canada's Northwest
Is there power at the headlight switch? I would expect two power supply wires one for headlights and one for park lights.
 

DMiller

Senior Member
Joined
Feb 21, 2010
Messages
16,424
Location
Hermann, Missouri
Occupation
Cheap "old" Geezer
Should be Battery at the fuse block, that feeds out on different contacts to the headlight switch then to the lights. Fuse slots should be marked as I remember as to Lighting Circuits.
 

funwithfuel

Senior Member
Joined
Mar 7, 2017
Messages
5,518
Location
Will county Illinois
Occupation
Mechanic
One problem those IH's had was corrosion at the main bulkhead connection on the engine
side of the firewall.
100% agreement. The male/female spade connections and the block were not well protected against moisture. Additionally , added circuits like dash mounted fans, extra running lights etc would overtax the connection and loosen the female spade with excessive heat.
ALSO recommend looking closely at the headlight switch itself. Those old ones supported 100% of the load, no relays. It may be a burned/loose connector assembly as well. I seem to recall that same switch and circuit used up till 90-91? Somewhere in there, when they switched to low current switches with load carrying relays. Good luck.
 

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
554
Location
Etowah Tennessee
100% agreement. The male/female spade connections and the block were not well protected against moisture. Additionally , added circuits like dash mounted fans, extra running lights etc would overtax the connection and loosen the female spade with excessive heat.
ALSO recommend looking closely at the headlight switch itself. Those old ones supported 100% of the load, no relays. It may be a burned/loose connector assembly as well. I seem to recall that same switch and circuit used up till 90-91? Somewhere in there, when they switched to low current switches with load carrying relays. Good luck.
Do you know if the fuse blocks are still available from International? If not would it be possible to retrofit from a newer model? This is a really nice old truck otherwise and I need to get some lights on it. We did get blinkers and brake lights but no fire at the headlight switch.
 

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
554
Location
Etowah Tennessee
100% agreement. The male/female spade connections and the block were not well protected against moisture. Additionally , added circuits like dash mounted fans, extra running lights etc would overtax the connection and loosen the female spade with excessive heat.
ALSO recommend looking closely at the headlight switch itself. Those old ones supported 100% of the load, no relays. It may be a burned/loose connector assembly as well. I seem to recall that same switch and circuit used up till 90-91? Somewhere in there, when they switched to low current switches with load carrying relays. Good luck.
I could not find any fire at the switch. I was wondering if I could run a hot wire straight to the switch from the mattery and put an inline breaker in it?
 

DMiller

Senior Member
Joined
Feb 21, 2010
Messages
16,424
Location
Hermann, Missouri
Occupation
Cheap "old" Geezer
Better off taking down the fuse block, inspect the Backside locate the real problem. It will just be a start as to wiring go dead to each function if don’t. Also lays the groundwork for incidental fires on backfeeds into the old wiring running new circuits.
The memory of “I run a new wire cuz the lights quit working”, where had birds nests of that style repair to wade thru and find real issues.
 
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