Total electric power loss, intermitent

[rob249]

On the way home from work yesterday, just got off the freeway, and had an instant loss of electric power, only lasted half a second, then ran normal. I turned into a parking lot and and it happend again, then back to normal. As I pulled into a parking space, it happend again, this time killing the engine. Once i parked, I tried restarting it, which worked, it ran for a couple seconds, then died again. While waiting for a tow truck, I tried it a few more times, each time, it would start, run for a second or two, then total electric failure. When it happened, I was at a high electrical load, A/c, headlights, turn signal. Trying to move it around my yard, it died a few more times and now I have no power at all.

I have another vehicle to drive for the time being, and ill be able to work on it this weekend.

My question is, what should i be looking for?

Im assuming its a broken ground, or battery/alternator cable, and not a fuse, although I think the headlights have auto-reseting breakers, dont know if there are any other breakers that could be bad. All my cables are OEM, and I had already planned on doing "the big 3".

Its a 94' Yukon, 5.7 TBI, new battery last month. Any suggestions would be greatly appreciated, thanks.

 

[east302]

With a new battery last month, it may just be a cable didn’t get tightened good and came loose from it. Positive side-post cables (if that’s what you have) have to be sandwiched together so check if they’re tight together.

 

[someotherguy]

1994 and older there's only 1 positive cable, not the dual arrangement the later trucks have trouble with.

I would expect if you had a loose battery cable you would experience trouble starting the truck as that's an extreme high load situation and usually turns up loose connection issues quickly. It's still smart to start there and ensure good connections, though.

Based on symptoms and a wild guess, my suspect would probably be the ignition switch. The 1994 and older design is pretty stout and doesn't often have issues (1995-up redesign is a whole different story) but at the age these trucks are getting to, we're going to start seeing new types of failures crop up.

1994 and older the electrical portion of the ignition switch is on the steering column about midway down towards the firewall.

Richard

 

[df2x4]

In addition to what's already been mentioned, I've had a side terminal on a battery fail inside the case and cause intermittent connection issues. Highly unlikely but something to be aware of.

 

[heskahoka]

I have had very similar symptoms on an earlier GM vehicle. Power cuts out intermittently, engine dies.

Turns out that it was a stretched fusible link. Check the link from your positive terminal to the junction strip for too tight or loose.

Similar situation in this video.

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[pressureangle]

Fusible links fail so infrequently that most people don't even know what they are, so when they do nobody knows what to look for. Check them carefully.

 

[rob249]

I replaced the ignition switch, to no effect. Ill start messing with the positive cable

 

[rob249]

So, im an idiot. Started tracing my fusible link back, Its fried and broken. I didn't see it at first due to the new wire conduit I had placed over it a couple years ago. Wish I had seen that before I replaced the ignition switch, but at least I have a new one of those I guess. Can I replace this with a new wire of the same gauge, or is there something special about it?

edit; Or should I replace the whole positive cable to starter and battery as well?

 

[heskahoka]

Can I replace this with a new wire of the same gauge, or is there something special about it?

A fusible link is a special type of wire, stranded, that is designed to melt in case of a power surge. It is designed to 'give up its life' to save the rest of the wires in the harness. You can buy replacement sections that you can cut and splice in.

If you power cable looks good, I would just replace the burnt out section with a new link.

Great video on fusible links here:

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[GoToGuy]

It's often sold on bulk roll, just get the size and length you need.