Thread: For 70s-80s gm truck guys...82 k5 Blazer - Electrical issue

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Friday night, my 1982 k5 w/350 ran great. Drove my other truck, saturday. sunday, the blazer wouldn't start.

what i know:
-battery voltage is fine, and BATT terminall on fuse block reads same.
-things i've installed myself that bypasses the fuse block, such as my fog lights, and power port work fine. (the circuits are fused individually)
-headlights/taillights, starter, dash lights do not respond.
-all fuses in fuse block are fine.

at first, when it wounldn't start, i thought bad neutral position switch or ignition switch. neither problem would affect the headlights, though. since they are dead, i'm looking for a problem with the hot lead or ground for the fuse block. i felt stupid, yesterday, when i found the wire i thought fed it did not. i'm working in the dark, with a maglite, since i get off work late, and i haven't replaced my droplight yet.

i don't know how the heck sitting for 24 hours killed my truck. if anyone has diagrams of the fuse block or advice that could save me some hassle, i'd really appreciate it. thanks. at least this isn't my dd, thankfully.

Does the engine crank and not start?
If so, have you checked the distributor 12 volt feed (the wire to the cap) to make sure it has voltage when the ignition is at the RUN position. Have your cousin put his tongue on a spark plug wire while you crank the engine (just kidding).

Does your distributor have a pigtail wire connector coming out of the bottom side of the metal part of the distributor? If so, this is the ESC (electronic spark control) and is probably the problem.....disconnect the connector (4 wire pigtail as I remember) and jumper the black and blue wires together on the distributor side of the connector....dont reconnect the connectors. You can use a short piece of junk wire to test it. It should start if the ESC was bad. What the ESC is doing is changing the timing so your jumper is taking the ESC out of the timing loop. You can permanently fix it with a jumper wire installed with some waterproofing OR you can get a HEI module that doesnt have the ESC pins...from an earlier model.

mike in tucson

no. the engine does not attempt to start. turn the key and nothing. absolutely nothing. no starter solenoid engagement, no dash lights, nothing. unsettling dead silence.

nope. no esc on the old beast.

this could take forever to hunt down since i have no idea what the cause is. it was just sitting there in the driveway. very frustrating

fusable link is burnt out, gaurenteed. check the starter S wire, that's your likely wire that has the burnt link, or possibly a fuse box feed

Your major clue regarding the problem is that the headlights, etc. do not work. This obviously rules out anything in the starting circuit such as solenoid, ignition fuseable link, starter key switch, etc.

Let's tackle the obvious first.
(1) a battery can put out 12 volts and still not have enough oomph to work the lights or starter. Measure the voltage with and without the lights on. Does it always show 12 volts or higher? Honk the horn...does it honk? If no, does the voltage drop when you push the horn button? Even a good battery will dip in voltage when the horn honks. If no, go to item 2
(2) check your battery cables. I have had cables corroded at the battery post interface and corroded inside the cable jacket. Take your battery cables off and clamp a good set of jumper cables to the terminals, the plus will go to the alternator stud (or the starter stud) and the minus should go to the engine ground. This takes the battery cables out of the system. Now, turn on the headlights. If the headlights work now, one or both of your cables are crap. If not, something else is wrong.
(3) Is your ground strap to the engine connected? Use one of your battery cables and make a ground between the engine (like the alternator bracket where the negative battery cable attaches) and to the frame. Again, use the headlights as a test.

I will bet on the battery cables as being the problem....but try the others too.

mike in tucson

the battery is definitely healthy. as of last night, it can easily power my offroad lights at 100 watts apiece.

i checked the ground strap last night, as well. securely fastened to the engine, firewall, and the extra point on the frame that i added when i installed the engine.

as my original post said, i've been hunting for the damn fuse box feed, and it turned out not to be the one i thought.

starter is fine. i tested it with jumper cables to the battery, sunday.

i keep the battery cable connections clean, so they're fine. even with the flashlight, i couldn't see what i was doing when i was trying to check the positive battery cable. i plan to grab a new droplight tonight, after work, and search for breaks or insulation tears.

it's actually easier to mess with this junk when you build it yourself. you remember where you ran everything, not where some bonehead po or a company put it. and the po of this truck was a major bonehead.

thanks guys.

Fusible links will cause your problem, and arn't that uncommon.

saturday, i checked the battery cable and the wires with fusible links. all fine. then, i started digging under the dash and found a little box crammed way in there that was obviously not stock. the po had removed the alarm to install in another vehicle, but he forgot a piece...a kill switch. i'm not certain what tripped it, but some snipping and splicing took care of that issue.

thanks for all the suggestions.