84 gmc jimmy(k5) electrical

greenandblackjimmy

Member
Joined
Mar 25, 2012
Location
Johnson county
So yesterday I got off work at three after nine hours of work & I had to drive home in the rain. I had my headlights on. At something like 8:30 at night my fiance gets home and tells me my lights are on, I go outside cut the lights off and start the truck. The truck started right up but of course it wasn't idling right. My tach light went off on it's own and then I turned the truck off. After turning it off when The key was turned nothing would happen and the tach light wouldn't come on. I pulled the battery and charged it over night. At 5 am this morning I hook the battery back up because it's fully charged. Still no light and the engine won't crank. The only electronics I see working is the head lights can still be turned on. Is there a fusable link between the starter and the firewall bulk head electrical connection that powers things in the interior?
 
Does that year have a fusable link in the starter wire from the ign sw? Looks like a bulge in the wire with a piece of wire that will burn out like a fuse. (Need a Haynes manual or, look it up online) If so, cut it out and put a heavy butt connector in it's place to test it with.Sounds like you need to break out the test light and check where you arent getting power.
Could be the ign. Switch, firewall plug for the harness is loose or shorted (Wiggle plugs and harnesses while you have someone try cranking it), usually a simple thing once you track it down. You say your tach LIGHT isnt working... If you meant the tach quit reading, I would say it is the distributor. Tachs read off the coil on the HEI's.
 
tach won't light up or move at all when the key is flipped to a start position
 
Check with a test light and see if you have power switching on and off with the key at the IGN terminal on the dist cap. You can unplug it from the cap to make it easier. If no power with the key in the run/crank
position, it is either a broken/shorted wire, loose terminal on the ign. switch/fire wall plug or a bad ign switch. You can jump it from the battery to see if it will crank and run.

If you have power there, it is probably a ign. module or a coil. Advance and Autozone test ignition modules for free. Be sure and put the supplied dielectric grease on the metal bottom of the module when you install it. It is right under the rotor button with 2 wire terminals plugged into either end.

Hope that helps.
 
I found that I have a blown fusable link, I replaced the fusable link with a inline fuse 30 amp. The truck will start and run then right away pop the fuse and start to run bad. Can't I run a inline fuse instead of a fusable link? (I did on my 85 dodge) or is something else bad?
 
  • A fuse is fine in the signal wire to the solenoid.
  • Does it pop the fuse when you are cranking it... or while it is running?
  • You need to check that the factory ground wire from the block to the chassis is good, and make sure you have a extra one from the chassis to the neg term on the battery. Weak or non existant grounds can cause this type of trouble.
  • Pull the ground strap and scrape the mounting areas on both down to clean metal and wire brush the bolt.
  • Is the starter solenoid releasing when you turn the key loose, or does it continue to run?
  • I assume the battery is hot and strong, and the starter is not dragging when you crank it, right?
  • Ign switches are cheap and easy to replace. If you dont see a bad wire in the harness and the starter tested good, stick one in it and see what happens.
  • If that dont fix it. Its about got to be in the harness.
 
Yes the battery is fully charged. it pops the fuse right after the truck starts running. I'd added more ground wires a while back. the starter solenoid does release.
 
You probably have a short. A wire is rubbing on a sharp metal edge, or on another bare wire somewhere. Pull the wires out of the loom and look them over good. Put a fuse in it and look for arcing at night when you move stuff around. When a fusable link or a high amp fuse melts out, wires get hot and can melt the insulation. 2 wires can be fused together.
 
I'm having the coil tested tomorrow at auto zone, and I'll look over the wiring again. When the truck starts up and runs and the fuse pops the rpm's go all the way up on the tach with the engine running at a low idle.
 
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