01RedSS

iTrader: (2)

Mods, wasn't sure which forum to put this in, Please move it to the correct one.

Driving down the road last night heard a pop, and the dash lights went out, stopped and ate, got back in the car and whole cluster and radio doesn't work.

Today I checked all the fuses with a test light and the Power Acc and Taillamp fuse was blown. Changed them, everything worked and shut it off. Went back out to wash the car and it has blown both fuses again.

I just had the car apart while painting it, checked to make sure no wires got pinched or cut etc and everything looks fine. Electrical is not my strong point.

Anybody else had issues like this before and could give me some pointers?

Thanks

Adrenaline_Z

Under what conditions are the fuses blowing?

It seems that the fuse(s) does not blow immediately which tells me there isn't
a direct short

or

There is more than one event that hasn't occured:

IE: Press the brake , while the radio is on.

The latter would indicate a mix up in wiring. Do you happen to have an
aftermarket stereo with additional wiring?

Did you ground a stereo component ground wire to the brake light system?

In any event, DO NOT place a higher rated fuse in a socket that is not designed
for high current. You WILL start a fire, or damage something.

Do you know how to use an Ohm Meter?

If yes, pull the blown fuse and touch the probes across the fuse socket.
What is the resistance? If it's zero, or close to zero, something is shorting.

If there is "sufficient" resistance with the probes touching the socket, start
pressing the brake, or anything that caused the fuse to blow initially
(whether it's circuit related or not) and ensure that the resistance does drop
to zero, or close to zero.

If it does, post the reason/action that caused resistance to drop

IE: I was measuring across the Power Acc and the resistance dropped to
zero when I turned on the A/C.

01RedSS

iTrader: (2)

Thanks, Ill try this, the car is bone stock except for a lid and filter, no aftermarket stereo etc.

The car was off when I installed the fuses, I started the car and everything was working, I shut it off and didn't move it. Came back later to pull the car out of the garage to wash it and everything was dead.

I'll try to dig up my meter and post back what I find.

Adrenaline_Z

Hey, I just noticed a typo, but you`ve quoted it so I can`t edit.

The last paragraph should read:

`...and ensure that the resistance does NOT drop to zero, or close to zero.

If it does, post the reason/action that caused resistance to drop.`

01RedSS

iTrader: (2)

Results:

Tail lamp Fuse:
Key on .05
Key off .05
Headlight switch on key off 16.64
Headlight switch off key on 16.35
Switch on key on hit brakes 16.06
Switch off key on hit turn signals 16.20
Switch on key off hit turn signal .03

If I have the car off, put in a tail lamp fuse it blows as soon as I turn on the headlamp switch

Power Acc fuse:

Key off, door open 16.06
Key on door open 16.0x
Key on, door open, switch on 15.84

Can't make it jump around really by hitting brakes, turn signals, radio, AC, power seat

Think the headlamp switch is bad?

Adrenaline_Z

No, I don`t think the switch is bad.

There must be a short between the load (bulb) and switch.

Unless the headlamp switch is directing current to ground, then no it can`t
be the switch. The switch is supposed to provide a resistance free connection
when it`s closed.

I would locate the circuit wiring in question. Remove the `load`(bulb, etc.) to break up
the circuit.

Then use the ohm meter between the frame/chassis and the wire sections
to rule out a short/pinched wire.

You might want to triple check wires harnesses, looms and strands to make
certain they are not pinched between a door, or body panel after painting.

Adrenaline_Z

Does anyone happen to have a detailed wiring diagram of these two circuits?

I have a feeling the short is happening after the `flasher` because the
resistance drops to 0.03 ohms only when the car is on , and the signal is
engaged.

01RedSS

iTrader: (2)

So I should remove all the bulbs that tie into the headlamp switch, and test each one by itself? Should I replace each bulb after testing?

The headlights still work but obviously the tail lights don't, should I remove the headlights also?

BTW, I did change a turn signal bulb that had blown out the other day, Actually had 2 blow out recently and the connectors look slightly charred, but I blamed it on the bulb failing. (Both front turn signals)(right then left)

Adrenaline_Z

Check the harness. I think that`s the problem.

If not, i bet some shielding melted further up the wire and is touching the chassis.

By removing the bulbs, you can isolate sections of the wire into small lengths.

That will help you pinpoint the short.

01RedSS

iTrader: (2)

Just double checked

Key on, Switch off, Signal on .03
Key on, Switch on, Signal on 14.62

01RedSS

iTrader: (2)

Just to clarify, I changed the turn signal bulb today, the fuses originally blew last night.

I'll try what you said, check the harness for the front bulbs that blew?
What exactly am I looking for? Just a burnt wire?

01RedSS

iTrader: (2)

Another question, are the front headlights/turn signals tied into that fuse? Because those still work while the tails do not.

Adrenaline_Z

With the bulb out of the harness, probe the prongs.

If there is a short, the meter will read close to zero.

I wish I knew how that switch was wired. I have a feeling you're very close
to finding the problem now...and I don't want to lead you down the wrong path.

Adrenaline_Z

Look in the area of the tail lights.

If the front turn signals are working, then the circuit and/or short is isolated from the tail lamps.

Just remember, current will take the least path of resistance. If the tail lamps
have half an ohm of resistance with the key on, of off, that seems to be the
location of the short.

Some of the tail lights are used with the turn signal circuit. That explains
the low resistance when the turn signal is engaged.

The front lamps wont burn out because they have resistance and the current
will flow to ground via the least path of resistance (tail lamp circuit according
to your resistance values).

01RedSS

iTrader: (2)

Am I checking this with the switch off? Because as soon as I turn the switch on it blows the fuse. Sorry, got a little confused.

Adrenaline_Z

I would leave the car off, and turn signal off.

Pull the bulbs from the tail section.

Probe between the socket prongs, and also probe between the socket prongs
and chassis ground.

From the info you have posted, the short is happening whether the car is on,
or off.

I also recall an electrical problem with the center mount spolier lamp/brake lamp.

Check that too.

01RedSS

iTrader: (2)

Will do,

The woman wants to go to dinner, so I will post my results tommorow after pulling the rear apart. Thanks for your help so far. I appreciate it.

eallanboggs

iTrader: (1)

If you could actually hear a POP when the fuse blew the short is in or near the passenger compartment or else you wouldn't hear it. Since the fuse now blows immediately you have a direct short to ground. NOT GOOD! You need to split the circuit in question in sections by opening up the connectors between the fuse box and the failed component. You then put in a known good fuse and one at a time start plugging the connectors back together. You should start at the power source side (fuse box) to plug the connectors back together. Once the fuse blows you have isolated the AREA where the short is located, but you have not as yet spotted the EXACT location of the fault. All you know at this point is that the faults lies between the connector you just plugged in and the one just before it. Now you must trace out the wires that go to the failed component between those two connectors. That's where you'll find the pinched wire. This sounds like a pretty generic way to troubleshoot this problem and it is, but it will lead you to your problem as long as you have a schematic wiring diagram which I'm sure you do and I'll be you even know how to read it too.

eallanboggs

iTrader: (1)

I should have mentioned that the POP you heard wasn't the fuse blowing, but was actually the sound that an arc makes when you insulation fails and a HOT wire meets bare metal face to face. At the point where this occurred you should be able to spot some soot or pitting on the bare metal where the insulation failed. When you fined an area that looks smokey your work is just about done. Man, your on your way to becoming an electrician the hard way.

01RedSS

iTrader: (2)

Looks like I had pinched the small peanut bulb wire on the passenger side rear tail lamp, The reverse light also appeared to be shorted out, pulled it, put it back in and it made a spark but didn't come on, switched it around and it works.

Both fuses appear to be holding, I'll see how it does over the next couple days(ran out of 20amp fuses so a 15 is in there right now).

Thanks for your help!