This720Guy Posted January 19 Report Share Posted January 19 So I am new to this page, but I desperately need some help I have a 1985 720 that I purchased a new fuse box for. The old one looks to have caught on fire at some point in the past. The issue I'm having is that the new wire colors don't match up to the old wire colors. On top of that it seems that some are not even in the same spots. I know nothing when it comes to electricity and I'm at a lost with what to do next. I thought this would be an easy fix..:( 1 Quote Link to comment
datzenmike Posted January 19 Report Share Posted January 19 What was the old fuse box out of? It really shouldn't matter. Ive replaced one before. Bad contact causes resistance causing heat that melted the plastic causing bad contact in a positive feedback loop. Release the terminals I think I used a straightened hair pin, and transfer to the new block. There are four blocks of fuses. From the left, the first 5 fuses are turned on by the ignition switch. Fuses 6 and 7 are also on when switched to the accessory position. Fuses 8 through 13 are powered by the battery and are hot at all times with fuse 9 blank and unused*. The last two are 14 and 15 and are for right and left side headlights respectively and are powered at al times. * you can see that blank position in the picture of your fuse box. Quote Link to comment
This720Guy Posted January 19 Author Report Share Posted January 19 I don't know what the old fuse box is out of. I assume it is the original fuse box, and are you sure the color of wires don't matter. Quote Link to comment
datzenmike Posted January 19 Report Share Posted January 19 The '80 fuse box is the most different with only 10 fuses. The '81 and up should physically be the same for the rest of the 720s but the '81-'82 has a blank space for the #5 fuse which is used in the '83 and up for the electric fuel pump. Color wires don't matter as you'll be putting yours into it. Above, the colors on the left side agree with what I have for the '81- and at least to '84 Below, this could be '85- '86 I just don't know, but can't see any reason to change them. However from April '85 there was a Z24i engine option with throttle body fuel injection. Maybe??????? Quote Link to comment
This720Guy Posted January 20 Author Report Share Posted January 20 Ok, so I got the fuse box hooked up. The truck is running now. But it just strangest thing when I turn my truck off. It stays running. I can pull my keys out and it stays running and I don't know what I did wrong. Quote Link to comment
This720Guy Posted January 20 Author Report Share Posted January 20 I tried my best to put everything exactly where it came from Quote Link to comment
datzenmike Posted January 21 Report Share Posted January 21 For now just disconnect the battery to shut off. I guess this was not happening before? Two things... 1/ Are the gauges still reading with the key off??? 2/ does the windshield wipers work with the key off??? Quote Link to comment
This720Guy Posted January 21 Author Report Share Posted January 21 Yes the windshield wipers still work with the key off And as for the gages, I don't really know because none of them really work. But the battery light is on, on the instrument panel Quote Link to comment
This720Guy Posted January 21 Author Report Share Posted January 21 And as for getting the vehicle to shut off. I have just been stalling it out in first or I will cut off the fuel pump and let it run out Quote Link to comment
datzenmike Posted January 21 Report Share Posted January 21 But that would eventually discharge the battery as things are powered still. 13 hours ago, This720Guy said: Yes the windshield wipers still work with the key off And as for the gages, I don't really know because none of them really work. But the battery light is on, on the instrument panel Well that isn't right. This is your old box. At the bottom the White/Blue stripe provides power from the ignition in the ON position along that side of the box for the 1-5 numbered fuses. The first five fuses share that White/Blue power source and it is separate from all the others. Above that is a White/Red wire from the ignition switch that is powered in the ON and the Accessory position for the 6 and 7 fuse only and separate from the others. Above that is a White wire that powers 8 through 13 and is hot at all times. Last is the 14 and 15 fuse that is powered by a Red wire that is hot at all times. So that's 4 separate sections on that side of the fuse box. Check that side of your new box has 1-5 6-7 8-13 14-15 separate from each other. Quote Link to comment
This720Guy Posted January 21 Author Report Share Posted January 21 I'll check it in the morning with my voltage meter Quote Link to comment
datzenmike Posted January 21 Report Share Posted January 21 The first two will turn on with the ignition. The second one will stay on when in Accessory only. The last two will be on at all times. On the hot side of all fuses there should be a separation into four groups. A visual inspection will expose if they are or are not. Quote Link to comment
This720Guy Posted January 28 Author Report Share Posted January 28 They are not Quote Link to comment
datzenmike Posted January 28 Report Share Posted January 28 Well then that's the problem. Certain functions need turning off/on with the key others like the horn, headlights, brake lights, clock, interior light should be powered and available at all times. You have the old fuse box I hope??? Perhaps a dremel could be used to sever the buss bar on the right side into those four sections and it should work properly. Quote Link to comment
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