Duchess Dies On The Freeway

[Jonathan Annear]

While cruising along today at approximate 55mph with the radio and the headlights on, I turned my wipers on when it started to rain. I heard a pop and then the car died. I had popped one of my fuses and the car refused to start. In fact, it would not turn over like it normally does. Instead, it was slow turning and inconsistent. After searching under the dash, I came upon a blown fuse and swapped it out for the one that supplies power to my blinkers. The car sat for 15 minutes and needed to be jumped from repeated starting, but with the cables connected, it came back to life. Any idea what would cause this scenario?

[billnparts]

Too many items running through one circuit. Run separate fused feeds for each individual component, wipers, radio, lamps, etc.

Bill Ascheman
Fiberfab Ford
Modified 5.0, 5sp., 4:11
Autocross & Hillclimb
"Drive Happy"

[Jonathan Annear]

The thing I’m wondering is how wipers blowing a fuse would shut down the entire vehicle.  I was thinking possibly the voltage regulator?

[KentT]

The wipers should be on a fuse that is only powered when the ignition is on.  Depending on exactly how it is wired, this could also be the circuit that is feeding power to the coil.  Blow that fuse, and there’s no spark to sparkplugs…

Suggest you add a “piggy-back” fuse box to split out and separate all these circuits that should be hot only when the switch is on.  Use one high-amp circuit (wire and fuse) from the main fuse box to a smaller 4-6 fuse box, then wire the circuits from there, with appropriate-sized fuses.

This technique/box is often called “power distribution box” or something similar… 

Just off the top of my head, some of the circuits that should be hot only when the ignition is on could be (if you have them):

1.  Coil, most importantly, and this also feeds the fuel shut-off solenoid on a VW carb to prevent “run-on”

2.  Wipers

3.  Turn signals 

4.  Fog lights or driving lights

5.  Radio, amplifier or other accessories

6.  Backup/reverse lights

7.  Heater/defroster fan

8.  Gauges (and senders)

If your car has an “accessory” position on the ignition switch, it should/could  power some of those circuits, but NOT power the coil.  Consequently, you should leave the coil circuit on the main fuse box, and perhaps power the remainder from the “piggyback” fuse box.

Circuits that were typically always “hot” were (again, if you have them):

1.  Headlights (and parking/running lights)

2.  Brake lights

3.  Horn

4.  Cigarette lighter

5.  Dome light or other interior light – perhaps even in the trunk or engine compartment

6.  Emergency flashers

KentT2013-06-28 10:17:45

Early FF TDr on 69 VW pan
Slowly coming back from the ashes...

[Author]

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