Scared of electrical fires

[kwm]

Started my car up today to get to work.

1) started instantly
2) Idling up high because it is cold
3) rolled up the elect. windows and closed elect. sunroof
4) turned on radio

About 10 secs. later I heard a pop pop snap snap in the dash. Noticed the pop snapping was interfering with my idle. Rpms dropped for a split sec. with each snap pop. Turned the olfactory setting up a few notches to try to smell anything, nothing. Noticed my fasten seatbelt light flashing on and off with the pops (I already had the seatbelt on and it had turned off just after I put it on) and now it is completely off.
I am really paranoid about electrical and fires b/c this car already caught on fire once before due to electrical. I can live w/o the fasten seatbelt light but is this a sign of further elect. problems? Are shorts under the dash likely to lead to a fire? The blower motor in the smugglers box shorted and locked up about a year ago. The PO also had the large 25amp fuses in every terminal of the fuse box. This lead to the trunk carpet, and heater ducts to catch fire while I was in bumper to bumper in the Hwy. I exit and drive like a maniac to a McDs and put it out. Insurance covered the repairs and I now roll with my own fire extinguisher. Now that the car is PROPERLY fused at the box will this not prevent any fires?

[Jim Sims]

"will this not prevent any fires"

No, it appears the damage has already been done. Sounds like your 25 amp fuse PO was another one of those guys who skipped science class in high school. Many of the wires are routed together and one over heating circuit or wire will melt through the insulation of adjacent wires. Then all it takes is vibration to again short the bare wires to each other or to bare chassis sheet metal possibly causing another overheating and fire situation. Having the correct fuses in place now may not help depending upon where the damaged wires are. The correct fix is to inspect and repair the wiring harness.

[kwm]

Many of the wires are routed together and one over heating circuit or wire will melt through the insulation of adjacent wires.

but would those adjacent wires not lead to a now properly fused junction?

Also if I was to have a electrical fire (please Lord no, please Lord no) is disconnecting the positive battery terminal the first step to stopping it?

[304065]

I agree with Jim, you will no doubt discover, as I did once, that the wires behind the dash have melted to one another. For example, there is a brown ground wire that feeds the back of the gauges, and a red wire with black stripe that feeds the +12v. These chafe against one another and after a while everything shorts. Also, the +12v black wire with blue stripe that feeds the gauge illumination is NOT FUSED, so when it rubs against the brackets for the heater, same problem.

To fix this correctly you need:

1) Patience
2) Remove all gauges from the frontside and heater box from the back.
3) Photograph all wiring connections so you can get them back on correctly
4) Download factory wiring diagram from PP or use the one from the shop manual.

You also need a source for the correct wire. Don't even think of using wire that's a different color, this will ruin your golf game, wilt your prized rose bushes, erode the value of your 401(k) and cause very embarrasing moments when you go to sell the car.

The correct wire is available from:

www.ynzyesterdaysparts.com
or www.riwire.com

As are the correct brass faston connectors and rubber insulation. You want to make it just like original: no crimp-on cheapo radio shack connectors or solder joints without strain relief. By removing the fried wires you can get a sense of the proper length for the new ones.

Good luck! I've been there and done that, it's not easy.

[Jim Sims]

Disconnect the battery GROUND strap to isolate the battery in the event of an electrical fire. Given your car's situation one might even install a quick disconnect switch in the battery ground strap link.

[pieterk]

John, to jump in with a related question, the wiring in your car is an inspiration. My 74 Carrera is mainly a track car, and I'd like to systematically tidy up and rewire the electrical, bit by bit, as it's a bit messy, and several electrical components have been removed from the car; and I'm also paranoid about electrical fires. I'm not concerned about being period correct, just about having the safest, strongest, best connectors and wire possible. I'm quite handy with a soldering iron (I've wired up too many Neutrik TRS and XLR connectors) and have a voltmeter.

Would that still include the faston connectors and original rubber insulation, or is there something even better? In fact, if you can recommend any additional resources with general guidelines, that would be great.

Part of my idea includes chasing any unused wire back to its source and just removing it. I'd really like for my electrical to be tidy.

Also, what did you wrap your harness with? It looks like electrical tape in the photos I've seen, but I'm guessing it's not. If you've seen the black flexible plastic spiral cable wrappers available at A/V electrical stores, would that work?

[rick-l]

Originally posted by kwm
Also if I was to have a electrical fire (please Lord no, please Lord no) is disconnecting the positive battery terminal the first step to stopping it?

Removing either battery terminal will isolate the energy source that is heating up the wires. Of course if the ohmic heating has caused something to reach ignition temperature it won't put that out.

Most people remove the negative battery terminal because when you are flaying about with a wrench you are less likely to arc weld the metal wrench to the body.

[kwm]

I like Jims idea of the quick disconnect. Although I am unaware of any battery ground strap that may exist.

pieterk- can you come over and bring that soldering iron with I will put you up at my house for about a week, feed you and keep you liquored up (when you are not working with the hot iron that is).

I am so not looking forward to this. I tried to get my shop to do all of this when the bill was being paid by my ins. co. after the fire but they were too moral to do so!?!?!?!?!?!? They went in and replaced individual wires but would not do the whole wire harness behind the dash b/c they said they could not effectively parcel out the ins. co. cost and my cost.

[Wil Ferch]

Any "other" chances of electrical fires ???

Just to make you even MORE paranoid.. I'll repeat here what I said in another post-->
===================================

There are many more electrical areas ( besides adding dash instrument light fuses)..Porsche does a really poor job in this category.
- For A/c cars....add the 7.5A fuse kit for the front condenser fan. Another fire hazard.
- add headlight relays, as mentioned
- add upgraded relay with external 16A fuse in smugglers box ( A/c system)...late 70's to late 80's cars.
- oddly *all* relays that Porsche uses ( ex: foglight relay) is fused only on the power side...not on the control side. Quick wire switcheroo will fix this.
- fuse box disaster. Design uses riveted construction of fuse holders that may get loose over the years. At some point in time, take box out, re-tighten or solder the rivet connections. Some of these have "bus-bar" connections that jumper incoming points on the fusebox. Or use external wire jumpers. Best to add external wire jumpers *everywhere* there is a bus connection with no external jumper wire to begin with. This would end up being a duplicate, parallel circuit.
- 930 A/c system gangs too many loads into too few circuits. Steve Grosskemper ( again) ....or was it John Rice..offers suggestions on how to add more fuses to separate these loads and have the wires run cooler. I think this article resides somewhere in the Pelican Tech Article section.
- no headlight relays ( as mentioned)
- other interior lights are still not fused with this mod ( cig lighter...fresh air panel).

I could go on....but I'm getting ill again thinking about all this...and all the work ahead of me to remedy these "excellence expected but not achieved" designs. What did Porsche do?..hire apprentice electrical designers??

- Wil

[pieterk]

KWM, how far are you from the Smokey Mountains? I'll solder, and then we drive!

I had a wonderful trip through there three years ago a few days in to a two week 5,000 mile cross country trip in a friend's 87 MR2. Next trip will be in a 911!

Seriously though, if I wasn't bogged down with work, I might just take you up on that. Do you have an iron? If not, do yourself the favor of buying a good, professional iron with variable temperature. Do some practice runs on an old broken radio or something. Be sure to tin the wires correctly before actually making a connection. I'd guess regular solder is fine, but personally, I always use silver solder. At least that's how we do it with studio electronics. If there's something different to the technique with automotive, hopefully someone with far more expertise than I have can chime in.

[kwm]

pieterk- I do live about 2.5 hours from Deals Gap (home of 318 turns in 11 miles featured in Excellence magazine this month and AKA "The Tail of the Dragon") Nov. 5th there is a big 911 run you want in? Buttt, you do live in cayon country so I am sure you have similar access.

[randywebb]

summer interns, Wil...

[Jim Sims]

Consider putting something like this in series with your battery ground strap:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?function=Search

[randywebb]

Jim -- "Sorry, the item number is not a valid item."

[Jim Sims]

Shuffle, shuffle (sound of digging HF catalog out of paper recycling bag): Item 92688-2ASB, battery cut-off switch $2.99; 100 amp capacity at 12 volts (1000 amp surge capacity at 12 volts).

[randywebb]

thanks!

what do you think happened to the URL?

www.harborfreight.com/cpi/ctaf/displayitem.taf?function=Search