Cascade Crew

alloy · Posted: Sat Jun 11, 2011 3:10 pm Post subject: Accessory electrical power loss

On the 89 I have lost power to the radio, windows, hatch, ect. But it still runs and has brake lights and turn signals. All fuses are good, so are the breakers in the fuse box.

I'm guessing it's a fuseable link, or a relay. I'm working on it tomorrow and don't really have any access to the net then, so thought I'd ask the question today. A friend loaned me a mitchell's manual for 89 vehicles, but I thought someone might have some words of wisdom to share with me about this.

aaron_sK · Posted: Sat Jun 11, 2011 4:04 pm Post subject:

Some cars have additional fuses/relays in an auxiliary panel with the blinker module.

If you suspect a fusible link they're easy to test. Just yank on them. Bad ones pull like a rubber band.

Leejo2005 · Member Joined: 12 Jul 2009 Posts: 466 Location: Kennewick

There's a bunch of fuseable links near the starter. I think 3. One of them could have blown, cut, or burned on the exhaust.

alloy · Posted: Sun Jun 12, 2011 5:07 pm Post subject:

After a lot of checking I've found that I have no power to the accessory buss on the fuse block. The one I'm pointing to in the pic is the wire that has no power to it. I took a jumper wire and put power to it and everything works. I checked all the fuseable links by the starter and they are all good. Other than a broken wire I can't see why there is no power.

Ideas?

Al Hasse · Posted: Sun Jun 12, 2011 6:08 pm Post subject:

The purple wire or the red one? Is there power to it at the fuse block? If not, then the problem is most likely in the block, possibly a broken bus bar where the wire attaches. If yes, then you most likely have a broken wire.

alloy · Posted: Sun Jun 12, 2011 6:43 pm Post subject:

The red wire. Everything else is fine. I jump power to the red wire from an external source and everything works perfectly.

I would hate to run an external wire to power that part of the box, but finding a break in the harness will be extremely difficult I think.

Xophertony · Posted: Sun Jun 12, 2011 10:27 pm Post subject:

Looking at my factory service manual. I see several fusible links on the starter. One of them powers the hatch fuse, light switch, courtesy fuse, and it's difficult to follow, but at least one or two others.

Just because a fusible link appears to be fine, does not mean they work. Use a test light (or DVOM) and check for battery hot on all those wires, check them again after the fusible links. That should be where your issue is.

If the fusible link is ok, and you have power flow from there, the accessory power wire joins the large loom that is bolted to the transmission bell housing. You are not getting those wires loose without pulling the transmission, or getting lucky. Unless of course you were smart enough to pull those clips the last time you were back there Wink

because of the difficulty of getting to the fusible links for testing and repair, I am an advocate of cutting them off, and replacing them with the appropriate fuse and running them directly off the battery.

One counterpoint that was raised by the Dewey Llama when I have mentioned this is that the fusible links can take a few little spikes here and there, as they are simply one gauge smaller wire, shielded in plastic. A fuse will 'pop' with a few extra amps. I have been running two different fire birds without fusible links now for a year or so with no ill effects, but I would recommend placing the fuse in an easy to reach location, such as adjacent the battery.

On a fuel injected Firebird, with the Battery on the driver's side, this has the added benefit of removing about 3 feet from that wire. the three feet that have been the most exposed to heat from the block over the last 20 years.

I do not know if you can get replacement fusible links anywhere. I have never looked.

blue89 · Posted: Tue Jun 14, 2011 6:54 am Post subject:

Without looking it up, I believe you want 2 gauges smaller. And by that I mean, a 10 gauge wire would use a 14 gauge as a fusable link.

The thing to remember here is wire and insulation melting points. A fusable link is a fail safe against a dead short. It does not have the same properties as a fuse. You could run a fusable link to the point that all of the insulation melts off. So I would advise against replacing it with regular copper wire unless you know it was fused downstream, which you are. Knowing is half the battle.

aaron_sK · Posted: Fri Jun 17, 2011 7:46 pm Post subject:

Do not cut off the fusible links and replace them with fuses.

Do you think every engineer who designed every modern automotive electrical system was just smoking crack?

Seriously now.

Give them a good yank. If they past that test throw a multimeter on them. If one fails go down to NAPA and buy a new one for a couple bucks.

Also, two gauges (numerical four numbers) smaller is correct. 10ga = 14ga, 14ga = 18ga, ect.

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2328

aaron_sK · Posted: Sat Jun 18, 2011 5:55 am Post subject:

I agree with you 100% there Rodney, and I don't even think the solenoid should be down there. GM did it to cut costs vs. the way Ford did it.

Whenever I do a rewire I grab a junction box and throw it on the firewall or fenderwell somewhere. Run a wire from the hot-side of the starter there, as well as a wire from the alternator charge post. Then pull all of the fusible links off of that box.

blue89 · Posted: Tue Jun 21, 2011 12:33 pm Post subject:

That sounds like a great idea Aaron. Would make it look better down there.

Xophertony · Posted: Tue Jun 21, 2011 3:30 pm Post subject:

Out of curiosity, why off the hot side of the starter instead of the battery?

aaron_sK · Posted: Thu Jun 23, 2011 4:37 pm Post subject:

Most accessories need to be connected to the alternator before the battery. That way a voltage drop at the battery won't cause dim lights/ect.

Just in general it's a bad idea to hook things to the battery. The only time it makes sense is when something will be drawing power directly from the battery (as opposed to the alternator) like a winch.

For most cars the only wires coming off the battery will be hot to starter solenoid, ground to block, and ground to chassis.

blue89 · Posted: Thu Jun 23, 2011 8:19 pm Post subject:

It's cause your battery only starts the car. The alternator powers things when its running. So run 4awg from the alternator to a post and run everything else to that post. I guess it would work to run everything to the battery, but that would look ugly and be a pain if you have to service it.