Fusible Link Solution
- Thread starter AZDELICA
- Start date
AZDELICA
New Member
Same amperage, although I have seen comments that the blade fuses would not necessarily have the same performance characteristics as the stock units. Time will tell. Debated using fusible wire and this just seemed like it was worth trying before getting into wires that burn up in your engine compartment. Easy/cheap fuse changes if they blow...(or could probably jam a fusible wire in there in a pinch...)
The fuses are quick reacting, fusible links are slow... The fuses will be more prone to failing with short spikes; but I have no idea if it will be problematic.
detroadster
Well-Known Member
All of my links in the battery box area are electrically functional but the connector housings are garbage. They are brittle, broken, and loose. I'd like to start fresh and just replace them all. Found some on Amazon that are kinda general purpose. Look like they'd work fine and Im conformable wiring them up. But my question is: How do I tell the amperage rating of the OEN fusible links so that I can replace them with the right ones? The electrical manual calls out things like "Fusible link Box 0.85R" and "Fusible Link for Glowplug Circuit FTX 1.0" I cant seem to find the amperage ratings. Anyone know?
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Fusible links aren't usually rated in amps*, because they're not intended to blow at a certain current. They're just intended to be a deliberate weak point in the wiring loom, the first piece of wire to melt if the circuit is overloaded (saves replacing the wiring harness). They're rated in cross sectional area, like the wiring loom wires.
The four fusible links by the battery are usually 3x 0.5mm2 (green) and 1x 0.85mm2 (red). In American wire gauge 20gauge is 0.5mm2, but 0.85mm2 would be 17.5gauge which doesn't exist. 17 gauge (1mm2) would probably be ok, since it's still smaller than the 3mm2 wires it's protecting.
LOCK: power door locks, power windows.
DEF: rear windscreen defroster, rear blower.
LIGHT: Take a wild guess. That's right; headlamps, interior lamps, stop lamps, indicators...
IGN: Anything that's switched on by the ignition switch.
Fusible link wire colours are standardised, but as usual the best thing about standards are that there are so many to choose from. Japanese fusible link colours are different to US colours. Yay!
The important thing about fusible link wire is that the insulation is rated to contain the melted metal without catching on fire. Regular wire of the correct gauge would melt at the same time as a fusible link, but it might also set fire to the engine bay.
*You can calculate how many amps it'll take to melt a fusible link wire, you just need to know the resistance of the wire, its melting point, ambient temperature, and thermal conductivity of the insulation. You'll end up with a graph that says "at 40A, this wire will take 10 minutes to melt. At 60A, it'll take 3 minutes (etc. and for example)). Regular fuses also work this way a little (a 60A fuse will usually handle 80A for a few seconds, longer if it's cold out) but they're designed to minimise this "feature".
The four fusible links by the battery are usually 3x 0.5mm2 (green) and 1x 0.85mm2 (red). In American wire gauge 20gauge is 0.5mm2, but 0.85mm2 would be 17.5gauge which doesn't exist. 17 gauge (1mm2) would probably be ok, since it's still smaller than the 3mm2 wires it's protecting.
LOCK: power door locks, power windows.
DEF: rear windscreen defroster, rear blower.
LIGHT: Take a wild guess. That's right; headlamps, interior lamps, stop lamps, indicators...
IGN: Anything that's switched on by the ignition switch.
Fusible link wire colours are standardised, but as usual the best thing about standards are that there are so many to choose from. Japanese fusible link colours are different to US colours. Yay!
The important thing about fusible link wire is that the insulation is rated to contain the melted metal without catching on fire. Regular wire of the correct gauge would melt at the same time as a fusible link, but it might also set fire to the engine bay.
*You can calculate how many amps it'll take to melt a fusible link wire, you just need to know the resistance of the wire, its melting point, ambient temperature, and thermal conductivity of the insulation. You'll end up with a graph that says "at 40A, this wire will take 10 minutes to melt. At 60A, it'll take 3 minutes (etc. and for example)). Regular fuses also work this way a little (a 60A fuse will usually handle 80A for a few seconds, longer if it's cold out) but they're designed to minimise this "feature".
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FamilyDelica
Member
Anxious to hear about the long term results.
detroadster
Well-Known Member
Thanks @Growlerbearnz ! Is length of the fusible link section critical? Example, if I replace 4" of fusible link is it best practice to replace with exactly 4" of new fusible link?
Here's what I'm grappling with. It's the 3 fusible links on the left side battery (I think they are all fusible links):
#1 - Big fat fusible link with black insulation (I think this is maybe for the glowplugs)
#2 - Green fusible link
#3 - Black with blue stripe fusible link
Anyone know what these 3 are out of curiousity? I'd like to label them for future reference, especially after I swap them out for different links with different colors.
Here's what I'm grappling with. It's the 3 fusible links on the left side battery (I think they are all fusible links):
#1 - Big fat fusible link with black insulation (I think this is maybe for the glowplugs)
#2 - Green fusible link
#3 - Black with blue stripe fusible link
Anyone know what these 3 are out of curiousity? I'd like to label them for future reference, especially after I swap them out for different links with different colors.
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In theory the length is important, but it's not *that* important. I'd say as long as you're within an inch of the original wire it'll do the job.
#1 is indeed for the glow plugs, it's 1mm2 tin plated fusible link wire, but any 1mm2 fusible link wire will do. 16 gauge should do.
#2 is for the AC compressor and fans, it's 0.5mm2
#3 is the junction between the starter relay (under the drivers seat beside the glow plug relays) and the wire that goes to the starter motor solenoid. Not a fusible link ;-)
#1 is indeed for the glow plugs, it's 1mm2 tin plated fusible link wire, but any 1mm2 fusible link wire will do. 16 gauge should do.
#2 is for the AC compressor and fans, it's 0.5mm2
#3 is the junction between the starter relay (under the drivers seat beside the glow plug relays) and the wire that goes to the starter motor solenoid. Not a fusible link ;-)
92_talon_awd
Active Member
If you want to go OEM the fusible links are still available for a very reasonable price on Amayama.
#1 is MB328732 and is about $5
#2 is MB249345 and is about $3.50 (this is for the green .5mm wire, there is a different part number if you have .85mm red wire)
#1 is MB328732 and is about $5
#2 is MB249345 and is about $3.50 (this is for the green .5mm wire, there is a different part number if you have .85mm red wire)
speedyquest
Well-Known Member
Not to waylay this conversation, but coming from the Starion community those cars also have lots of fuse-able links and they love to be spotty as they get older. My personal solution to that was also replacing them with fuses but what I did was measure the amp draw for each circuit and then decide on an appropriately sized fuse.
detroadster
Well-Known Member
Brilliant! Thank you!
detroadster
Well-Known Member
I ALMOST went and looked but forced myself not to. The reason being is that I have some brake lines that literally left Japan yesterday. 1 day too late to add them to my Amayama order. Doh!!!!
92_talon_awd
Active Member
Nooo!! Isn't that always the way ha.
sealica
Active Member
I'm wondering if there is a specified fuse box layout for red/green/diameter on the LOCK/LIGHT/DEF/IGN. Box on top the positive(+) battery terminal?
sealica
Active Member
In other words red = 0.5mm2 and it goes on ignition, with green (0.85mm2) going on the others?
InstrumentOfPeace
Active Member
I’ve replaced a few previous vehicles I’ve owned. I believe it’s suggested to use Maxi fuses.
Also, you may (I’ve started looking) be able to find a newer model (maybe out of a 400) to see what they replaced it with. A fuse box located in the engine bay that handled the battery, starter, and power back to the accessories. Then swap that in and remove the fusible links. It’s a partial upgrade to the power distribution system.
Also, you may (I’ve started looking) be able to find a newer model (maybe out of a 400) to see what they replaced it with. A fuse box located in the engine bay that handled the battery, starter, and power back to the accessories. Then swap that in and remove the fusible links. It’s a partial upgrade to the power distribution system.
sealica
Active Member
Alright looks like the answer is 0.5mm2 except IGN which is 0.85mm2 (for most L300s). “Australian minibus” uses a second 0.85mm2 on LIGHT.
moroza
Active Member
Hm, every fusible link I've replaced (BMW, mostly) has been rated for a current.
Another suggestion: circuit breakers. There are quick-blow and slow-blow types. Some are useable for both AC and DC, and some only one or the other. Some reset automatically after some seconds, others manually. It's reasonably common for vehicles (91 Ford F250 and 98 Passat, for example) to use automatically resetting slow-blow 30A breakers on power window circuits, which are more prone to overloading in routine use. When they get old, they can get a bit dodgy, but are typically designed to fail open (safer), not closed.
Another suggestion: circuit breakers. There are quick-blow and slow-blow types. Some are useable for both AC and DC, and some only one or the other. Some reset automatically after some seconds, others manually. It's reasonably common for vehicles (91 Ford F250 and 98 Passat, for example) to use automatically resetting slow-blow 30A breakers on power window circuits, which are more prone to overloading in routine use. When they get old, they can get a bit dodgy, but are typically designed to fail open (safer), not closed.