84 3+3 454 sm465 - No power, fusible link?

[Affende]

truck has been running mostly fine. drove to work today and it was uneventful. parked, left the lights on, and came back out to ZERO power whatsoever.

No dash lights, no crank, no fuel pump (its a loud electric one mounted right under the driver seat) ....


Had my multi-meter so i checked battery and had great voltage on both optima red top batteries.

poked the insulation on the fusible link (one of the MANY wires jammed into the junction block) and had continuity across the fusible link.

are there other fusible links? if so how many and where? Would leaving the lights on burn out the headlight switch and cause this problem?

Im pretty frustrated (BMW died first week of january) and the truck is now 30 miles away (caught i ride home with a co-worker).

the electrical on this truck is a #$*%*$ mess. I have already been talking to gmachinz about rewiring the entire truck this summer, but it bit me before i could do that.

any help is appreciated. Im down 2 vehicles right now and out of luck ...

 

[Dougnsalem]

Did you have voltage to the junction block? There are two fuseable links at the starter. One goes to the junction block, and then it feeds through another one, which is probably the one you checked.

The other one at the starter goes to the alternator, but it also splits off and heads through the firewall connector. So, do you have power to the alternator? (Easy way to check that fuseable link). I still need to look and see what exactly gets fed by the line that splits off, and goes to the firewall connector.....

Can you read schematics? (Serious question- not ment to sound like an ass) There is a great wiring diagram in the technical library....

Fuses and links are like light bulbs. They heat up, and cool down, and can eventually blow even if you don't have any issues....

Easy fix- jumper wire from the battery to the junction block, and another from the battery to the alternator. That should bypass the links(except for the one you checked as being good). Get it home, then crawl around under it and check the ones at the starter....

 

[Dougnsalem]

Easy fix (part 2)....

This is assuming that a link is your problem. I'm still looking at the wiring diagram. Did you happen to check for power at any of the fuses? That will be the best clue to where your issue is....

 

[Affende]

Did you have voltage to the junction block? There are two fuseable links at the starter. One goes to the junction block, and then it feeds through another one, which is probably the one you checked.

The other one at the starter goes to the alternator, but it also splits off and heads through the firewall connector. So, do you have power to the alternator? (Easy way to check that fuseable link). I still need to look and see where exactly what gets fed by the line that splits off, and goes to the firewall connector.....

Can you read schematics? (Serious question- not ment to sound like an ass) There is a great wiring diagram in the technical library....

Fuses and links are like light bulbs. They heat up, and cool down, and can eventually blow even if you don't have any issues....

Easy fix- jumper wire from the battery to the junction block, and another from the battery to the alternator. That should bypass the links(except for the one you checked as being good). Get it home, then crawl around under it and check the ones at the starter....

I was too frustrated to think clearly and actually check what i should have checked .... so i dont know if there was power to the junction block or the alternator. I can check those tomorrow though, as i did leave the DVOM in the truck, which is what i used to verify battery voltage.

I can read electrical schematics as well as i can read greek poetry while wrangling alligators in a mosh pit ... so i honestly take no offense to your question. The extent of my knowledge is tracing a line or two and hopefully finding the right ones in the engine bay. but being able to look at a schematic and use it as a diagnostic tool to figue out what is downstream of what is well outside my knowledge ... electrical work is wizardry to me.

What size wire should i use as jumpers? if i can get it home i have a much higher chance of a proper fix ... which i hear is an inline fuse?

 

[Dougnsalem]

I was too frustrated to think clearly and actually check what i should have checked .... so i dont know if there was power to the junction block or the alternator. I can check those tomorrow though, as i did leave the DVOM in the truck, which is what i used to verify battery voltage.

I can read electrical schematics as well as i can read greek poetry while wrangling alligators in a mosh pit ... so i honestly take no offense to your question. The extent of my knowledge is tracing a line or two and hopefully finding the right ones in the engine bay. but being able to look at a schematic and use it as a diagnostic tool to figue out what is downstream of what is well outside my knowledge ... electrical work is wizardry to me.

What size wire should i use as jumpers? if i can get it home i have a much higher chance of a proper fix ... which i hear is an inline fuse?

I would say that you should be safe using some 10 gauge for each jumper, as long as you aren't running lights or a lot of other things (heater fan mainly). Two 10 gauge wires to each would be safest. Now, if you go to do those jumpers and there is a LOT of sparking, or the jumper wires start getting hot and start smoking..... Well, you could have a short going on, and the jumpers won't help/work....

EDIT: (Liability Disclaimer) It would be best if the jumpers had a heavy duty fuse to prevent catastrophic meltdown. I'm not recommending people to randomly toss in jumper wires!!! Lol

 

[Affende]

Easy fix (part 2)....

This is assuming that a link is your problem. I'm still looking at the wiring diagram. Did you happen to check for power at any of the fuses? That will be the best clue to where your issue is....

I did not ... i was too damn mad over two vehicles in two weeks going down on me.

 

[Dougnsalem]

Don't stress out on it. Electrical doesn't get much easier than these things. Side post or top post batteries? Could be as simple as a loose terminal end on a cable....

If you want, I can PM you my number. I'm still checking the wiring diagrams right now, however, at the very least, you could call me tomorrow. I can walk you through what to check....

 

[Affende]

I would say that you should be safe using some 10 gauge for each jumper, as long as you aren't running lights or a lot of other things (heater fan mainly). Two 10 gauge wires to each would be safest. Now, if you go to do those jumpers and there is a LOT of sparking, or the jumper wires start getting hot and start smoking..... Well, you could have a short going on, and the jumpers won't help/work....

ill take some 10g to work tomorrow and see what i can get going. ill try one at a time to see if i can narrow down which side needs work.

which fuses should i check to help narrow things down?

 

[Affende]

Don't stress out on it. Electrical doesn't get much easier than these things. Side post or top post batteries? Could be as simple as a loose terminal end on a cable....

If you want, I can PM you my number. I'm still checking the wiring diagrams right now, however, at the very least, you could call me tomorrow. I can walk you through what to check....

that would be great man. it wont be until about 445 my time (Mountain) ... you will have to talk to me like an idiot, real small words and you might have to repeat them.

Side post batteries, i checked connections at the batteries but did not check connections at the isolators, etc. ill check that on lunch tomorrow so im not wasting too much of your time on simple stuff.

actually, a loose connection makes sense to me no that we are talking. The last week so so the truck has randomly lost all power and then regained power while driving ... fast enough so i cant get my foot off the gas ... but slow enough to where there is PLENTY of slack in the drivetrain to snap your neck back when it fires off again. all happens within about half a second.

 

[Dougnsalem]

that would be great man. it wont be until about 445 my time (Mountain) ... you will have to talk to me like an idiot, real small words and you might have to repeat them.

Side post batteries, i checked connections at the batteries but did not check connections at the isolators, etc. ill check that on lunch tomorrow so im not wasting too much of your time on simple stuff.

actually, a loose connection makes sense to me no that we are talking. The last week so so the truck has randomly lost all power and then regained power while driving ... fast enough so i cant get my foot off the gas ... but slow enough to where there is PLENTY of slack in the drivetrain to snap your neck back when it fires off again. all happens within about half a second.

Captain Obvious here, but I gotta say it.... Lol. Check the grounds too. I like to turn the key on with the heater blower on high, so if I hit an intermittent connection when I'm pulling on wires, I'll hear it. Be good to do this before even opening the hood.

Had a some time to check the diagram a little more....

You should have 12v at the alternator batt terminal.
That checks one starter link, and the link by the junction block

You should have 12v on the red wire, on the 2 wire connector at the alternator. That's your other fusible link at the starter. It also goes to most of your ignition/fuse block stuff. Hopefully it's this and not something like an ignition switch. Be the easiest for you to get it home....

Sent you a pm with my number. Good news is this should fix your cutting out issue... That's a plus! Lol. You'll probably figure it out at lunch....

 

[Affende]

Captain Obvious here, but I gotta say it.... Lol. Check the grounds too. I like to turn the key on with the heater blower on high, so if I hit an intermittent connection when I'm pulling on wires, I'll hear it. Be good to do this before even opening the hood.

Had a some time to check the diagram a little more....

You should have 12v at the alternator batt terminal.
That checks one starter link, and the link by the junction block

You should have 12v on the red wire, on the 2 wire connector at the alternator. That's your other fusible link at the starter. It also goes to most of your ignition/fuse block stuff. Hopefully it's this and not something like an ignition switch. Be the easiest for you to get it home....

Sent you a pm with my number. Good news is this should fix your cutting out issue... That's a plus! Lol. You'll probably figure it out at lunch....

Thanks for taking your time to help me out. I looked over the 84 schematics and i found the fusible links coming off the starter and the junction block ... that only took me about an hour and a half.

kinda feeling like captain oblivious, here.

Ill definitely use the heater blower trick, thats a damn great idea for finding and intermittent connection.

ill take the test light, some 10g, wire pliers, and some terminals to work so i cann splice if needed ... DVOM is already in the truck.

Ill poke around today and see if i can find it.

I REALLY appreciate your help, man. I cant thank you enough.

 

[Dougnsalem]

Thanks for taking your time to help me out. I looked over the 84 schematics and i found the fusible links coming off the starter and the junction block ... that only took me about an hour and a half.

kinda feeling like captain oblivious, here.

Ill definitely use the heater blower trick, thats a damn great idea for finding and intermittent connection.

ill take the test light, some 10g, wire pliers, and some terminals to work so i cann splice if needed ... DVOM is already in the truck.

Ill poke around today and see if i can find it.

I REALLY appreciate your help, man. I cant thank you enough.

Not a problem at all. Hope I can help.

And I have to say a thank you to @hatzie !!! The wiring diagrams in the technical section are so easy to use. Big time saver when looking for a certain year.... It just sucks trying to read them on a phone.... Lol

 

[hatzie]

Try a tablet. LOL

 

[Affende]

got the truck fired up and back home. No idea what is going on with it. There was ZERO power anywhere on the truck (checked the alternator, starter, and junction block) except right at the battery and at the battery isolator.

I piddled with it poking and prodding around trying to try to make sense of what was going on.

yesterday i measured almost 20V on the primary battery and 13V on the auxiliary battery .... went back today and had 1V on the primary and 13V on the aux. I trust the meter, its a nice klein meter so i think the isolator is doing some funky stuff and letting voltage bleed back and forth depending on its mood.

so without going any further, i jumped the positive aux battery over to the positive primary battery and lights and blower motor kicked on (thanks to Dougnsalem for the idea to leave the key on and blower on to help find an intermittent connection).

after that it was a simple jump start (a truck hooked to the primary battery and a jump box hooked to the aux, just the truck on the primary batter wouldnt even try to turn it over).

let it idle 15 minutes to charge the batteries, shut it off and it fired right back up. turned it off, let it sit for 5 hours while i went home and got the wife (to play musical cars) came back and it fired right off.

so ... best i can figure ... there is either a problem with the dual battery isolator or there is a angry ex with a hoodoo doll poking it with a stick.

Im open to ideas and how to proceed from here.

 

[OkieFishMan]

I tell you a story I had with mine, a damn weird one at that. I once went out to start the square. Opened the door and the dome light came on, turned the key the seat belt light lit, went to fire it off and it just barely barked the starter, and everything went dark. No more dome light, not a damn thing. Went to the battery figuring it had bit it. It showed 12.5 volts, so it was good. So I started tracing things backwards from the fuse block. Everywhere but the battery would only show about a volt. I could even put my meter on the terminals and it only show one volt. So I took both terminals off, cleaned the hell out of them and the posts (they were already spotless), put them back on. So now its showing 12.5 volts everywhere, so I figure its fixed and go to start it. It barely barks the starter and BAM everything goes dark again. So I am like what the hell??!! I repeat this process about 3 times and then I replace the battery terminals terminals. I went ahead and cleaned all the wires that connected to the new terminals (they all looked fine) and put it all together. Worked fine. Never did it again. I figure it had to be a bad terminal (never even heard of that) or one of my wires to the terminal wasn't making a good connection. This was on a square I used to have that had been converted to top post. So you might want to make sure that your connections at the battery are all clean and in good shape.

Glad you got it home!