Total electrical shut down.

[Massboy]

Today while I had my Blazer running in the garage I had the radio playing, the seat heat on, heater fan on full, and the lights on. The seat heat is on a separate circuit with a relay closed by the ignition circuit so the load is on the feed from the driver's side battery.
While the truck was running I pulled the high beam switch back and withing half a second the truck just stopped and everything went dead. This is my M1009 which has been all converted over with a 86' harness. I believe I probably have a short in the high beam circuit that most likely popped the fusible link at the starter solenoid.
Do you guys think that is what happened and if so, where do you think I might look for the short? Would it be in the column or somewhere in the feed to the headlights?

Thanks, Ted

 

[4xcrazy]

Check that little junction block on the firewall, not sure if it gets corroded over time or what, Pauly383 had that happen to his truck a few times until we figured out it was a bad connection at that point. It's a main connection point that feeds all power to the fuse box.

 

[Massboy]

I quickly checked that before with my test light. No power there. That is why I think it's the red wire and fusible link at the starter. I haven't gotten underneath it yet to look. Maybe tomorrow. We've gotten about 15" of snow so far tonight. I'll be doing a lot of shoveling tomorrow.

 

[Mastiff]

It's been a while, but aren't there a pile of fusible links on the firewall? I remember debugging my CUCV and I could see I wasn't the first guy to be stabbing probes into the wire on each side of those things.

 

[Massboy]

There are more fusible links on the M1009 harness than the civilian for sure. I converted this over to a 86' civilian harness and it has about 5 links on the whole thing.

I did find the issue today and it was with the fusible link at the starter. It is a 14 fusible link in case anyone needs to know in the future. It wasn't the link but the connector at the stud on the starter solenoid. The wires were mostly broken and what was left were loose in the connector. It was a crimp connector somebody had installed to replace the original I guess. Shame on me for not changing it when I started redoing this whole thing. I took a new connector eye, pulled off the plastic insulator, and tinned it with solder. Cut the wire back and of course had the typical blackened corrosion on the wire strands. A quick brass wire brush to the wires allowed the solder to finally stick. Put some shrink tubing over the wire and then soldered the new connector to the wire. Slid the shrink tubing down and shrunk it right close to the eye connector. Connected the wires back to the solenoid stud, connected the positive cables on the batteries, turned the key, and "Shazamm!", no more issues. I didn't have a short in the high beams either. It was just too much load on those few strands with the high beams on.
I should have realized something was up when I was testing the tailgate window switch the other day. When the window bottomed it put enough draw on the system to pulse the voltage enough that my radio lost it's memory. After installing the new connector I tried the tailgate window too and found it no longer kills the radio memory even when holding it much longer than necessary. My power windows also work faster and better now plus the heater is blowing a little harder. A whole bunch is fixed with just that one wire.

 

[diesel4me]

I have taken those 2 red wires at the starter with the fuse links off the main battery post there at the solenoid and removed them from that stupid conduit tube they routed them in,which fries them often due to being right next to a red hot exhaust pipe and manifold...I've had several trucks "die" because of that in a bad place!..

I extend the two red wires with the fuse links on them and run them right to the battery's positive terminal(and I use that plastic split wire loom tubing to protect the wires)--just like GM used too on the older first generation 67-72's...now there is just the purple "crank" wire on the solenoid,and the positive cable to deal with--less wires to mess with or get burnt up under there..the fusible links get left intact,so the harness is still protected..

I noticed my truck was not charging sometimes the past few days,and my batteries seemed weak--but after checking the voltage at the plug on the altenator,it showed 12V at both wires,so the altenator should have been charging..checked the regulator terminals and there were clean,so were the contacts in the plug..the two wires are original and look beat though--but I found out it was charging OK,the amp meter on the dash cluster must have a bad connection..

After dorking around for half an hour testing wires and thinking about snipping wires and putting a new plug on the altenator, or swapping another known good altenator on--a good firm smack on the dash made the amp needle jump back to the "charge" position where it should be with it running..I hate it when you "make" a problem,when none really existed..
I still should change that plug anyway though--and my batteries are probably on the way out,I've had them in the truck 10 years now,and they were "old" then!..Duralast made a few good ones back then I guess..