Console/Radio fuse keeps blowing - Please help

[rundmc]

Hey all,

Installed a new head unit last April. Everything's been just fine since. There's an inline fuse, etc. Anyway, last week while parked with just the accessory setting on listening to the radio, the radio blacks out as do the console lights. I check the fuse box. Sure enough - the radio/console fuse is blown. Head to AutoZone, get a matching fuse, install it, fuse blows instantly.

Back to the home garage. Remove head unit to check connections. Nothing looks like it could be shorting. But I keep in mind that the console lights are also dead. While the radio is disconnected, I try the accessory setting on the starter. The console lights COME BACK ON. We plug in the radio, but don't place it back in the console and try the starter again. This time, the console and the radio BOTH COME BACK ON. We put everything back together and assume it was something weird with the cable positions behind the unit that needed rearranging, even though we didn't see any crimped wires.

This evening, we're going to head out. I turn on the DMC, engine is revving, radio is on and within two minutes, the radio and console go dead AGAIN. Fuse is once again BLOWN.

Can someone please tell me where I need to start looking now for the problem? Thanks - Mike

[1batt4u]

Maybe something with the ground wires?

[Ron]

Check the wiring going to the windows...

[rundmc]

Check the wiring going to the windows...

Have unplugged the window switches. Fuse still blowing instantly. Will look at wiring harness to see if it is something in there. Looks like console removal is unavoidable now...

[DMC5180]

You could have pinched radio feed wire or the feed wire has chafed against a metal edge like the pass thru of the Radio rack support. the rack is grounded via the ground wire cluster on the right side.

[Dangermouse]

Playing that Justin Bieber CD again, Mike? I think the radio is committing hari kari :)

Just for clarification, are you saying that the fuse in the fuse box is blowing, but the inline fuse is not?

I presume that the inline fuse is smaller amperage than the main? As Dennis suggests above, it is most like a chafed wire around the radio frame.

[WelmoedJ]

I think the radio is committing hari kari :)

New way of killing yourself, Dermot? :)

The Japanase called it Hari Kiri (seppuku).

[rundmc]

Thanks everyone! I will check around the radio frame. Unfortunately I'm going to be in Amarillo until Friday on business so I'll have to wait until next weekend to deal with it. Will keep you posted. (And you found me out Dermot, but it's my Call Me Maybe CD)

And yes, it's the fuse in the main fuse box.

[john 05141]

New way of killing yourself, Dermot? :)

The Japanase called it Hari Kiri (seppuku).

:histerical1:

[rundmc]

Pulled the console. Checked around the radio frame. No chafed connections. We disconnected the radio main power after disconnecting the head unit. Fuse still blows instantly. The window switches were out, the radio was out. The console lights were still connected.

Really pulling my hair out on this one. Is it possible it is a ground wire somewhere else in the wiring system? Where should I look? Is it the accessory setting on the starter? I looked at the wiring on the starter and it looks clean.

Any help appreciated.

[DMC5180]

Which fuse is blowing #11 or #17? Do you have a multimeter?

[rundmc]

Which fuse is blowing #11 or #17? Do you have a multimeter?

It is fuse 11 - the 30 amp fuse in the main fuse box. Yes, I have a multimeter. What do I need to do?

[WelmoedJ]

Pulled the console. Checked around the radio frame. No chafed connections. We disconnected the radio main power after disconnecting the head unit. Fuse still blows instantly. The window switches were out, the radio was out. The console lights were still connected.

Really pulling my hair out on this one. Is it possible it is a ground wire somewhere else in the wiring system? Where should I look? Is it the accessory setting on the starter? I looked at the wiring on the starter and it looks clean.

Any help appreciated.

If you have been fumbling with the cigarette lighter, this may be the culprit.
I have found that sometimes while turning the lighter unit, the ground pin of the lamp gets into the lighter fitting.
It than can short against the power contact of the lighter.

[jmettee]

Yes, I have a multimeter. What do I need to do?

You need to troubleshoot. Since you are blowing the fuse (& 30A is quite large), first suspect would be a direct short. Without the fuse in the block, I would do the following as a start:
1) Determine which pin is the +12V feed. Without the fuse, turn the key on & with the multi-meter in voltage mode, test between a known good ground stud & each fuse pin. Only 1 should have 12V. Do the same for the other pin & you should get 0 (or VERY close to 0).

2) Now that you know which side is "hot", you an turn off the key. Then the other fuse pin is known to go to the radio & other items. You can put the multi-meter into resistance mode & test this pin against the ground. You should get an open circuit, but if you get 0 or very low resistance, then you likely have a power wire directly shorted to a ground & need to start searching downstream of that wire/circuit.

An electrical diagram of the will be needed to continue troublshooting & tracing wired to the components that fuse feeds.

[DMC5180]

You need to troubleshoot. Since you are blowing the fuse (& 30A is quite large), first suspect would be a direct short. Without the fuse in the block, I would do the following as a start:
1) Determine which pin is the +12V feed. Without the fuse, turn the key on & with the multi-meter in voltage mode, test between a known good ground stud & each fuse pin. Only 1 should have 12V. Do the same for the other pin & you should get 0 (or VERY close to 0).

2) Now that you know which side is "hot", you an turn off the key. Then the other fuse pin is known to go to the radio & other items. You can put the multi-meter into resistance mode & test this pin against the ground. You should get an open circuit, but if you get 0 or very low resistance, then you likely have a power wire directly shorted to a ground & need to start searching downstream of that wire/circuit.

An electrical diagram of the will be needed to continue troublshooting & tracing wired to the components that fuse feeds.

+1

More importantly Statement 2)

You have a dead short (continuity to ground) Place the meter in the Ohms position W/ Sound (yeah its annoying) You'll also need alligator clips or leads to attach the probe ends. This frees you up start moving wires around. With any luck you'll break the short ,which stops the BEEP.

The Cigarette lighter is powered by fuse 17 (should be a purple wire) I don't see that being the problem unless a Lt. Green/white wire is attached to it.

All #11 fuse wires are Lt. Green/White. 12V for A/C mode switch, Radio, RED resistor, A/C panel lights (relay), Clock(if fitted) Gear shift Light (Automatic), and Window switches. I'd unplug said items and see if it breaks the short. You've already stated you pulled the window switches (no joy) so Pull the A/C panel illumination relay. If it breaks continuity you know the short is down stream from there.

[rundmc]

So I've pulled the A/C relay however, I am uncertain of what I now need to do with the multimeter? Do I replace the #11 fuse? Do I leave that out? I guess I need some step by step on what to do with the multimeter now that the main A/C panel relay is removed...Not sure how to check for continuity.

[DMC5180]

With Fuse removed,Connect the multimeter (RED lead) to the NON 12V fuse terminal if you can't poke the probe into it, then try a small flat blade screw driver and alligator clip the probe to it. Connect the black probe to ground. Your DEAD SHORT should cause the Ohms setting/w sound to make noise. If you've Removed the A/C panel relay already and the multimeter does not sound off or shows OPEN. then you need to probe down stream from the A/C relay socket. I think the terminal to probe is the center one or 87a. See if you have continuity to ground from that point.

[rundmc]

So I've determined that my multimeter is too primitive. It does not have alligator clip adapters for this job. So I begin to look for the right tool for the job--and now I'm very confused again.

I thought I would get a Fluke 115 with alligator clip adapters. Upon more research, I learn that a test light, a Power Probe and a Short Circuit detector are also possibilities. But I'm so confused. What combination of these is best? Do I need them all? Only some? Only one? Which ones?

[jawn101]

So I've determined that my multimeter is too primitive. It does not have alligator clip adapters for this job. So I begin to look for the right tool for the job--and now I'm very confused again.

I thought I would get a Fluke 115 with alligator clip adapters. Upon more research, I learn that a test light, a Power Probe and a Short Circuit detector are also possibilities. But I'm so confused. What combination of these is best? Do I need them all? Only some? Only one? Which ones?

You can get alligator clip wires for a few cents at harbor freight or radio shack. I think a pack of 4 was 99 cents at HF last time I was there.

[DMC5180]

So I've determined that my multimeter is too primitive. It does not have alligator clip adapters for this job. So I begin to look for the right tool for the job--and now I'm very confused again.

I thought I would get a Fluke 115 with alligator clip adapters. Upon more research, I learn that a test light, a Power Probe and a Short Circuit detector are also possibilities. But I'm so confused. What combination of these is best? Do I need them all? Only some? Only one? Which ones?


A simple 12V test light is fine for finding power. Most of the time this is all you need for the Delorean. It will NOT do continuity or OHMs testing, unless you find a combination probe set up for it. You don't need to spend big dollars on a Fluke unit. Nice as they are you can get by much cheaper. Unless you found a reasonably priced one under $50. As Jon mentioned you just need Alligator clip test leads. Your local Radio shack has lots of supplies like this and you can probably find probe lead adapters there too.

At this point have you Hand probed the fuse terminals to determine the hot side?

[rundmc]

With the use of a short circuit detector and the multimeter, I found the hot side of the fuse and then hooked up the buzzer. Sure enough, when switched to accessory, it went off like crazy. I started tracing the path back toward the console, making sure to move the wiring harness as I went. I fiddled with wires 20 minutes. That buzzer just kept buzzing. I moved wires in the fuse box, behind the fuse compartment, on both sides of the console, behind the radio bracket -- NOTHING.

The buzzer keeps buzzing and the short is staying hidden. Any suggestions?

[DMC5180]

If you hooked up the buzzer to the hot side, of coarse the buzzer is going be going off. You have to connect one lead to the Dead terminal then connect the other lead to a ground. place the meter in continuity mode (w/audio) if it is still shorted after all that wire movement you did it should still BEEEEEEEEEEP.

Disconnect ALL items in that fused circuit and try again. Do you have a schematic to reference? If not use the PDF in the resources section. For that fuse to blow the short has to be down stream from the box. also recheck your radio wires to be sure they correct and the splices are properly insulated. Did you pull the A/C panel light relay?

[rundmc]

I pulled the A/C panel relay, pulled the A/C panel bulbs (in case there was a short in the bulb housings), pulled the window switches, pulled the radio completely out. At a loss at this point.

Followed the instructions on the short circuit detector to the letter - it said to hook each end up to each fuse terminal.

Is it possible the fuse is blowing because of a loose connection in the fuse box on fuse 11? I have noticed that fuse has some play to it...

I will take my multimeter and proceed as you have instructed this evening.

When you say "downstream from the fuse box" you mean in the direction of the radio/console, correct? Not back toward the battery?

[DMC5180]

A loose fuse could cause Heat (melting) or intermittent operation. You have not indicated an issue like that. I would not worry about it for now.

Downstream is fuse box to the component side. (Not battery) in this case your looking at the termination points of the Lt. green/white wire. They must be disconnected from there component in order to isolate the wire circuits (guarantee no continuity thought at the component)

Component harness Termination points for the fuse 11 circuit:

A/C panel relay socket (Pull relay to isolate)
L & R window switch connectors(disconnect switches)
Rheostat (disconnect spade terminal)
A/C Mode switch (disconnect spade terminal)
Door lock indicator light socket. (remove bulb) also check the body of the socket make sure it is isolated in the A/C panel bezel. If its touching the radio rack that could be a dead short.
Gear selector light (if Automatic) The 2 wire connector, however, is in the harness regardless of it being in use. That could be a source of short if the connector end is wedged against grounded bracket.
Clock (If fitted) (separate White Plastic multi-way connector).
Radio(this has its own inline fuse) If that fuse is OK it's not the Radio Leg of the circuit after the fuse. this fuse is 5A rated and meant blow before fuse 11 (30A).

[Dangermouse]

I

When you say "downstream from the fuse box" you mean in the direction of the radio/console, correct? Not back toward the battery?

Think of the battery as the "source" of the river of electricity. The fusebox is then downstream of the battery, and everything else is downstream of the fuse box.


If you are still stuck, and can make it home one lunchtime, I can come over and see if we could thrash this out. I think I work near your house.

[rundmc]

Thanks everyone for your assistance. Last night nullset was able to stop by and we went through the vehicle and ultimately found it to be one of the connectors for the window switches. The infuriating part of it all was that I had checked the switches and connectors before I ever started removal of the interior of the vehicle. Nullset discovered, by accident while we were getting ready to test another part of the harness, that the wires going into the back of the connector were the culprit because the plastic barrier separating the power and ground had broken off at some point in the car's life and now the wires were touching inside the connector.

Wish I had known enough to turn the connector around before I ripped out all the interior, but lessons learned...

Dermot, thanks for the offer to assist. Even though I'm just seeing it now, it is much appreciated. (The past two weeks at work kept me off the Internet and out of the garage).