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truick fuse box has no power


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jackpruitt
Novice

Jun 25, 2019, 9:48 AM

Post #1 of 10 (259 views)
  post locked   truick fuse box has no power  

Got a 1989 Jimmy s154.3 ltr
Truck quit on me running down the road. Towed it to a garage and the mechanic said the fusebox had no power.
Unfortunately he can not find a wiring diagramI suspect if he found a wiring diagram heI could find out where the fuse box gets power from'he suspects the fusible link in that wire is toast.
The battery is charged according to the mechanic. No power to the ignition , radio, interior, windows or anything,

I checked around and found that the fuse box is either it is hooked up to the starter or it is hooked up to the alternator'
My mechanic can not find a wiring diagram . so he has stopped working on it.

He is stacked up work to do and he told me if he knew where the fusible link was at he could quickly check it andand replacing it if it bad will probably fix my truck but he can't find a wiring diagram.

So can anybody find a 1989 jimmy s15 wiring diagram and tell where the fusible link is?
Thankis, You help will speed up getting the truck fixed because that mechanic is so busy he is going topull off my job until he finds a wiring diagram


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 25, 2019, 9:58 AM

Post #2 of 10 (252 views)
  post locked   Re: truick fuse box has no power  

If he needs a wiring diagram to figure that out, then you need a new mechanic.

The fuse box is fed with fusible links which are special pieces of wire that melt internally when overloaded.

On that year they are probably at the starter. If there are additional smaller wires connected to the main terminal of the starter along with the battery cable, pull on each one and see if any stretch. If you have to replace any of then DO NOT use regular wire. This is fuse wire.

If the links are not at the starter, they may be at a junction box on the firewall.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 25, 2019, 10:36 AM

Post #3 of 10 (241 views)
  post locked   Re: truick fuse box has no power  

Had nasty on a full size not this but set up the same. ZERO anything inside? Was the rubber block full of spade connectors and old white grease. Twisted the spades to connect tighter it worked till that thing wasn't useable anymore! Dumb luck that day on a road call!


T



jackpruitt
Novice

Jun 25, 2019, 6:26 PM

Post #4 of 10 (221 views)
  post locked   Re: truick fuse box has no power  

   
Finally found the fuse link coming off a wire from the alternator that was toast and now I got power to the terminal block on the firewall as the tester lights up. There were two fuse links attached to the alternator. I believe the other one was on a wire that went to the starter but I am not sure.

there are two Wires from the terminal block that go into the wiring harness. I believe at least one goes to the ignition switch. Even though the wire is hot on the terminal block the ignition is still dead. Nothing happens when you turn the key. no lights , horn or radio. Nothing

I found a wiring schematic and two wires going into the ignition switch are red and bring voltage to the switch. Evidently from the switch the power is then transfered to the fuses when the key is turned. Yet right now nothing happens when you turn the key.

Is there something keeping power for the terminal block from getting to the ignition switch. I am thinking there maybe a bad relay that got toasted when the fuse link got toasted. It is either that or the wire from the terminal block is
broke before it reaches the ignition switch.

I found a bare spot on the wire next to the fuse link next to the alternator and I guess maybe there was a direct short. That wire coming off the terminal block appears to be about 16 gauge so I am wondering it goes through a relay before power gets to the ignition switch. If so then maybe the relay is bad now too. I really don't know as I have no idea where that relay would be. If there is a relay where is it? it would be great if all I had to do was replace a relay now.

The mechanic says he is going to connect a wire to the 16 gauge wire that is hot now and connect it to the two red wires that go into the ignitions switch. He wants to do that to three fuses on the fuse box that state on the
wiring diagram that the source of power is the alternator. I told him if he is going to connect wires to the hot wire first tie in the ignition switch because it may be in the circuit from the alternator to the fuse box and if so when you turn
the switch after it is hot it will send current to the fuses in the fuse box. So, I think he is going to do that first. .


(This post was edited by jackpruitt on Jun 25, 2019, 8:36 PM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 26, 2019, 4:24 AM

Post #5 of 10 (186 views)
  post locked   Re: truick fuse box has no power  

Again, this mechanic does not know what he is doing. The power supply does not come from the alternator. It may just be split off from there after coming from the battery.

I think you have another burnt fusible link and again, there are 2 that are attached to the alternator. Do not use regular wire to repair these and do not start jumping power from other sources or your problem will only get worse.





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Jun 26, 2019, 4:31 AM)


jackpruitt
Novice

Jun 26, 2019, 5:15 AM

Post #6 of 10 (167 views)
  post locked   Re: truick fuse box has no power  

This wiring diagram is has a generator. My 1989 Jimmy has an alternator. Are the they same except for one havingan alternator and this one having a generator?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 26, 2019, 5:22 AM

Post #7 of 10 (163 views)
  post locked   Re: truick fuse box has no power  

It's just the terminology they used. It has an alternator. Generators haven't been used since the early 60's.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jackpruitt
Novice

Jun 26, 2019, 12:43 PM

Post #8 of 10 (150 views)
  post locked   Re: truick fuse box has no power  

Went out to a GM dealer. They told me to have the mechanic put the ignition back in the truck.they said until it is completely installed he will not know if replacing the fuse links fixed the truck ornot.

They said since the two bad fuse links are replaced with in line fuses the ignition should and thefuse box probably will be getting voltage again after I told them the terminal block on the firewallnow had 12 volts.

They said since he had replaced the ignition cylinder he had disconnected the ignition
switch that is controlled by a rod that is attached to the ignition cylinder. Once the switch and rod is back attached
to the steering column and adjusted when I turn the key the power should be correctly routed to the right places to start the truck again. If it does not start then I will know I still have an ignition problem. They said they thought it
would start since I was not having any problems until the fuse link failed and that problem had been fixed.

The said both the in line fuse and the fuse link will protect the wiring and keep it frombeing damaged if there is a short. They said the difference was the fuse link took a lot longer to failthat an in line fuse. They told me they thought I could get a roll of 8 gauge fuse link at NAPA. They saidthey had no idea where I could get it if Napa did not carry it any more. I told them I would check.theysaid if I had to use the in line fuses I should go ahead and use it until I found some fuse link.

This made sense to me. I looked at the wiring diagram you sent me. It is so small can not read much of it. What I could read is enough to make me realize I need to take this to someone who is capable of figuring out what is wrong with the truck if I find it still won't start. My mechanic appears to be as confused as I am trying to understand the wiring diagram for the truck. I am just hoping fixing the fuse link has fixed my problem. I am betting it did after talkiing to the guy at the dealership.

I remember a few years ago I replaced the battery cable from the battery. When I put it backtogether I jumped in the truck and it did exactly what it doing now. Nothing when i turned the switch.
I went back to the battery and saw I had left off the second cable that was also attached to the positive pole of the battery. I put it back on and it started right up. I realize now the cable I had left off had the wire attached to it that went to the alternator and those two fuselinks were in that harness too. I am basicallyexperiencing the same problem again except it was due to the bad fuselinks. But this time I got anotherproblem trying to determine if the truck is going to get voltage necessary to run when the ignition switchhas not been mounted on the steering column yet because the mechanic has removed it when he replaced theignition cylinder lock. It was so worn out that it would start without a key. I wanted it fixed since he was workingon the ignition anyway.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 26, 2019, 1:40 PM

Post #9 of 10 (140 views)
  post locked   Re: truick fuse box has no power  

You just wrote a big long answer that basically confirmed what you were told already

The fusible links are your problem

Your mechanic doesn't know how to read a wiring diagram and doesn't know what he is doing. I don't know why he disconnected an ignition switch to change an ignition lock. It is not necessary. I don't think this year has a pellet in the key but if it does, this is never going to start.

Fusible links are used because they are slow burn and necessary for those circuits. This is why I advised to use only fuse wire. It can be bought at most any auto parts store, not just NAPA.

Yes, they feed the ignition switch so you won't see power at ignition controlled fuses until the ignition is on.

The big question now is ....... how did you blow both fusible links in the first place? Did someone hook up jumper cables or battery cables backwards? If that is the case, you could have even more damage.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 26, 2019, 4:41 PM

Post #10 of 10 (123 views)
  post locked   Re: truick fuse box has no power  

OK, I deleted your insults and I will close this thread when I finish this response.

I did in fact tell you what was wrong with you car and how to fix it in my first response. All your so called mechanic spewed was shade tree nonsense and Mickey Mouse repairs. You asked for the wiring diagram that I supplied and then your guy couldn't even read it.

Also you never stated that you had the ignition switch removed while you were doing your testing so that is on you.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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