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What size and type of glass fuses to use for 57 3100 original optional Fuse Junction Block?

I need to know what size AMP fuse to use for the Radio,
Deluxe Heater,
Original Electric Wipers,
accessory lights - (well I think these just pull off the Light switch Gray wire extention and maybe do not use a fuse).

So like 2, 5, 10 AMP or what?
Wires seem to be about 16-18 guage.

I do not seem any mention of the size fuse to use in the accessory guide or the wiring harnesses.

can't find a spec for the wiper, the original was connected directly to the hot end of the ignition resistor, I don't remember what I use, but 10a should be safe ... the fuse panel was only added to a truck that had multiple elec options installed, which is where fuses would then reside ... others:
backup - 9amp
heater - 9a
fog - 14a
park brake alarm - 9a
radio - 7.5a
spot lp - 9a
under hood lamp - 9a

Bill

Great! Where did you find that information?

The fuse Panel you show is the repro type but similar to the original I have except that their is no AIR CON on mine and the ACC is 90 degrees the other way and the mount is different. But basically the same.

I found it on my computer gathered over time, like lots of other parts info .... the fuse panel changed over the 5 years, from none at all in 55 to the one with AirCond on it, which I believe started being offered in 58, they were all "similar", and each year added positions - the 59 [and repro] had provision for about 3 more fuses than the 57, and was slightly wider as well as a wider mount bracket

Bill

Cool.

Mine is for the 57 and does not have the AIr conditioning.

But looking at the directions for installing it I have a question. The orignial NOS instructions say to put the 3 wires on it from the provided wire harness. RED to upper Left area of Junction block, and it runs to RED Battery Terminal with Fuse on Light Switch. Then it has a PINK wire to lower LEFT of Block which goes to ACCESSORY on Ignition Switch. And third is a GRAY wire that goes to Upper Left corner of Junction Block to the Light switch area.

So am I correct in assuming the following on the Junction Block?:
1) RED wire is always live (HOT) so all things I hook to those 4 or so tabs will always have power?
2) PINK wire provides Power to Junction Block while Key is ON to those tabs that you use in that area?
3) GRAY wire provided Variable Dimmer Light power intended for other Optional Dash lights - like Heater Bezel light control?

So are these 3 areas on the Junction Block all separate?
As in they are acting as 3 separate junction blocks, 1 for dimer dash type lights, one for constant ON power and one for Accessory Power?

The RED one seems to be Fused by the Light switch but it also has places for 2 Fuses on the block. One with 2 tabs and one with 1 tab for pulling power from.

The GRAY wire has 3 locations for Power to be pulled directoy and a 4th one through a Fuse. I do not understand the reason for this Fused one. Or should The GRAY wire be put on the bottom so that the 4 upper tabs are fused? That is not what the instructions show.

Here is a couple reference pictures:
junction_block
Installed
wired
Directions

On the GRAY I have the Radio light attached to the GRAY tab Upper Left.
And the Heater Light on the other GRAY tab.

On the Pink I have Radio Power, Electric Wipers in the "BACK Lamp" position and the Heater in the "BRAKE LP" position as I did not have a Long 9Amp fuse. for the Heater SLot.

In the RED I currently do not have anything attached.


I have not attached the actual Batter leads yet. I am trying to verify what I have hooked up prior to smoke testing and Frying all my new wires.....


Any comments/suggestions or explanations appreciated.

"A" question?? I'd have to dig one out and examine the connections, but from memory and the wiring diagram:
1) yes red always hot - connection at the light sw to the fuse block is a junction point, the fuse on the lite sw is for the lights - note that the other red wire on the lite sw there comes from the BAT terminal of the ign sw, the main power source .... the red should go the the strip of 4, where it looks like you have it

2) the pink wire to the ign sw is so the accys hooked to that area turn off with the key off, the pink will go to the single terminal end in that corner and the things hooked to the 4 terminal end will be fused together - not sure what was intended for there, but the LP would indicate things like a spotlamp or the glove box lite, or emerg vehicle lighting

3) the gray wire is for the accy dial lights, don't need to be seperate, but can be, or can be spliced into the cluster light wires, also gray [along with the light in the key sw] ....

the long metal strip with the fat red BATT wire is the power supply end of those 4 fuses, there is only one wire attached, and nothing will be fry-able if the other ends of the fuses go to the right items, but yes, that red wire is always hot and things on those fuses need to be turned off individually - just make sure everything is off before you hookup the battery and it should be fine

hard to be sure on colors in your pic, but it looks like you do have the [a] red feeding the 3 fused items hooked up, and no power or fuse for the 3 wires in the ACC LP position - although looks like a red wire on the unlabeled and unfused position at top?

Bill

Right.

I am picturing these as 3 separate Functional BLocks.

Since I have nothing I need to be ON without the Key on I have no fuse or wires to the RED wire area to the upper right.

My picture may be confusing as there are 2 RED wires. One with a White pastic end in the upper right corner and no fuses goes to the BAT.

The other RED wire with the BLACK end is from the Heater to get power off the Accessories PINK strip with the 4 fuse locations.

The Pink Area along the bottom should get power from the PINK wire from the Ignition switch. They all have separate fuses (not really fused together).

The GRAY pulls power from the light switch and I would think is variable as you turn the light switch clockwise and make it dimmer or brighter. The GRAY wire area with the 4 tabs Upper left of my pictures, has the place for a fuse and a single tab at the bottom of it. What is the purpose of that fuse? Seems to be for some other accessory or something but it would be variable power as it gets it's power from the GRAY wire that shares the tabs on the light switch that go to the Panel lights which are variable intensity?

I was thinking that the Fuse on the light switch was for something else (like some accessory) as the Switch itself looks like it has a Breaker setup in it that would disconnect and trip when it got too Hot from a short for the head lights and then reset when it cooled down.

except for the main strip of 4 fuses, each fuse position has one end with a single terminal and the other end has multiple terminals - the single terminal should be the only place you have a 'hot' wire, the other side of the fuse goes to the item powered

as above, the corner upper left your pic is labeled ACC LP, meaning accessory lamps, the single tab is where it gets power - what are the 3 wires you have there [on the other end of the missing fuse]? if one of those is the gray wire from the light sw, the other ones will be hot if and when the lights are on, [you're just using it as a "junction"], so it should be that the gray is on the single terminal and the other 2 [radio and heat control?] are fused, as they aren't now - yes, the gray wire only is hot when the lights are on, and dims with the dash lights which get power from inside the sw

the 2 bi-metal breakers on the headlight sw are for the headlights only, the small fuse is other functions in the switch [tail lites I think[ and is there regardless of any accessories

Bill

OK seems to still match my general assumptions, I think.

The Gray Wire with White connector is in the spot that the instructions say to put it which is on the Junction side (far top left tab). It is a group of 4 tabs. The other wires I have up there are Lights for the Radio(yellow) and Lights for the Heater(Grey with Black connector). So both will dim and be ON with the light switch but no fuse there. But there is that place for a FUSE below them with one Tab below the FUSE? I guess maybe that is so you could use this whole setup for something other than intended? Instead of using it for a GRAY lights junction you could run a HOT wire to the solo tab and then use a Fuse and have 4 tabs that use a comon fuse. If it was not meant for that then they have a place for a fuse for one wire to use but it would still be dimmed. That does not make any sense.

Wait. Looking at the instructions that came with it, it seems that their GRAY wire goes to the Top Left tab (top right in instrutions as they look at it from the rear) but the connector is HORIZONAL and only shown from the back. My connectors up there are VERTICAL. So Maybe the directions were for an older version of the fuse block. It all came in the same NOS box, which has since fallen apart.

But I am thinking like you said above that my Fuse block is different than the instructions show. I should run the GRAY harness wire for this Fuse Block to the single tab at the bottom of that 5 tab cluster, on the other side of the fuse. Right to the left of where it says "vHEATER" Then put in a fuse above it and then connect my Radio light and Heater Light wires (yellow and grey) to the 4 tabs on the other side of the FUSE.

This all would have been easier to figure out if Chevy had printed a picture of the front of the Fuse Block instead of just the rear of it! Who wrote these instructions!

OK I will move my GRAY wire that comes from the light switch to the single tab below the Fuse.

That makes more sense.


Well this other version of a Fuse Junction Block Different Fuse Block does not have a fuse for the Gray Lights just 5 tabs.

Mine locks different: My Fuse Block

So with Mine what size fuse should I use in the GRAY Lights fuse slot?

no, the intended use was as it's labeled: accessory lamps, meaning the radio and heat lights will be fused so that they don't blow all the dash lights if they screw up [unlikely] .... you've misinterpreted where the instructions say to put the gray wire, it is the power supply for the other 2 and there will be a fuse between them - as I said, any wire from a + supply is the single connector, any wire to a load is the opposite side of the fuse, multiple terminals or not

the later fuse block is a different arrangement, not "5 tabs" but one and the 4 others the fuse holder, I think you'd find there are connections across the back not seen on the front that power others to the right .... and maybe the gray wire isn't used later, the radio and heater lights can connect direct to the light sw, but fused seperate on yours I'd go with about 3amp, which is what that short fuse on the sw is

also note on the last pic of yous, the unused red wire is hooked where it can supply 2 unlabeled fuses, one right that can supply 2 items, and one left that can supply one item, that could be used to supply additional things later

Bill

ok I will change it to incorporate the Fuse on that part of teh FUSE block for the Accessory Lights.

Thanks again!

you now owe Bill $100

nice ... 'bolt consulting pays better than the day job

Bill

Your probably correct but then I have not connected the battery yet to see if anything sorts out. ;-)

for sure you need to do that...
if Bill tells you something, you can take it to the bank..