94 GMC pickup mystery starting problem
 

Guys, got a 94 GMC Sierra 350.
Looking to sell it, it's been sitting awhile but running fine when parked it.
Went out to fire it up this morning as it's been a bit cold here.
Almost started right up, but battery was sounding tired. jumped it off my other pickup, and now nothing. No dash lights, no headlights, no nada.
Any ideas?
thx!

Battery connections, or fusible link ?

It's not clear if the truck started when you jumped it, or if you tried to jump start it and it 'died'.

Are you sure the polarity was right on the jumper cables? There is likely also a main fuse that might have failed.

Get a multi-meter for $6.
Search results for: 'multimeter'
It'll tell you battery voltage levels, voltage drops, whether there's power to something, etc. Great for everything.

Popped main fuse? Are the engine/tran ground cables there and clean? Is there play in the ignition switch?
Start with the battery.

Hopefully you didn't cross the jumper cables?

OK no particular order:
No cross connection of cables. truck was almost starting but it's cold so battery was tired. After I connected jumper cables I got zip.
Checked and cleaned connections.
Fusible link looks OK
Messed with ignition switch tried neutral back to park etc.
Got a volt meter battery fine.
Negative to block reads fine.

No head lights or dash lights.
It's like there's no ground, but when I ground the block to the negative terminal with a jumper I still have nada

Sounds like battery is too dead to jump. Try another battery if you know your connections are good.

Put the jumper cable from the block to the body. You may not have a chassis ground, the engine might be insulated from the chassis, or you may have burned off a jumper.

Or just measure the voltage at the cigarette lighter and then from + to the engine block.

Good point. Pull the + off the truck battery and connect it to the jumper cable only.

And measure the battery voltage with the ignition and headlights on.

What exactly do you mean by this? Positive to block should show voltage near 12v. Negative to block should show continuity.

A thought on this:
A ground wire can be attached with one thin strand remaining, and still show continuity using the multimeter ohms setting.
But when the big amps start flowing, there will be a huge voltage drop there.
The best way to find this is using the volt setting on both sides of the connection while cranking.

Sounds like a cooked battery cell. Open the fill/vents plugs, do you smell rotten eggs?

Sorry boys, battery is good.
positive to block shows 12.6
I have had the bad ground cable before that's why I say I jumped the neg terminal to block and still no headlights.
All connections at starter fine,
Got to be a fcked cable I guess..

And all fused links appear fine.
Like I say, everything was fine until I jumped the bloody thing

Fusible Link - Ask the GM Technician - GM-Trucks.com
For what it's worth, GM uses 5.0 mm sq. fusible links on their factory auxiliary battery option for the charging wire. Two, actually. One between the battery and the relay, and the other between the relay and the starter. In additon, GM has a 40 amp Mega fuse protecting the loads from the Auxiliary battery.
...
A fusible link on the other hand, works for protecting from catastrophic damage from a dead short that isn't consuming the current by turning a motor, but is instead just generating heat. Thus the link melts apart, end of current flow.

Measure at the cigarette lighter...

If all dead and battery good - try fusible link - it's not quite what you think it is, looks different;

Sparky's Answers - 1994 Chevrolet C3500, Replacing A Damaged Fusible Link

For the record - just TWO DAYS ago, I got to replace a dead nuts shorted battery in my daily driver 1999. Cranked a little slow one day, next day nothing and would NOT take a charge. New battery, now zero issue.

angela

So here it is: the positive cable had failed just at the side post connection.
That's a first for me. ( don't get me started on the genius that decided that side post batteries were a good idea on a work truck..)
Chopped everything off wired it to a post clamp ( the battery had both side and post ) and presto changeo!
Flashed right up and the guy is headed over with the cash!
Thanks for the input guys!

Awesome! In true Pelican fashion - you got to the bottom of the issue and fixed the problem. Conquered!

Count me as another person who hates those stupid side posts...

angela