1974 Dart 2nd fuse blowout

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NoahSewal

NoahSewal

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Just got my car up and going again after doing the windshield seal and heater core/blower motor and replaced the carpet. I noticed i didn't have any turn signals which led me to realize that my number 2 fuse was blown out. i replaced it and it blew out IMMEDIATELY. my amp gauge bounced when i put it in and it popped instantly. this only happens when the key is on. the fuse is fine when the key is in the off position. on that fuse is the; back up and reverse gear indicator lights, blower motor, turn signals, and the radio. anyone have an opinion on this? i unplugged the blower motor already with no luck. the car is regulating the alternator fine.
 
I'm going to guess you pinched a wire somewhere. I'm thinking there's not a lot by the heater box unless the car has ac, maybe, cause I've never had an A body with ac.....resistor? Or more likely something under the sheetmetal along the floor by the doors. You were messing there when you did the carpet but I don't know of anything that'd be live back there when you power the ignition circuit....tail lights?Maybe steering column harness? Kinda common. Your directional don't work......hmmm
 
The amp gage is inline with the battery.
Whenever something draws current from the battery, the ammeter needle moves toward discharge.
Pointing at D indicates 40 amps discharging (which is a lot of current!)
Pointing halfway toward D is 20 amps, and is still alot of current.
Straight up is 0 amps. Neither discharging or charging.

Since it only happens with key switch in run, that eliminates all of the main feeds.
Further, that it blows a fuse narrows it down a lot more.

I agree that one of the circuit wires on that fuse probably got pinched or somehow is now grounding.
 
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Number 2 fuse on '74 A-body feeds:
Heater blower switch
Radio
Reverse Lamp switch
Turn signal flasher

If you have a multimeter or test light, leave the fuse out and check for continuity to ground.
I think the best initial approach is as suggested above - retrace what you did looking for wire cable that got caught or crunched.

If that doesn't work, then with with fuse out, start disconnecting the connectors and checking for continuity to ground.
Circuit is almost the same as a '73 which we helped someone with not long ago. His ground short was a wire on the transmission but that's neither here nor there. You were working on heater blower so that switch and its wiring is a likely area.
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Fetch fire extinguisher. Keep it close.

Disconnect everything in the circuit.
Install new fuse. It should not pop.

Plug in each thing. When it pops, bobs your uncle. If it pops with everything unplugged, the issue is in the harness.

On my car, the brake wire was melted to another wire inside the taped up harness, and new fuses simply resulted in smoke blowing from dash vents.

I'll wager there is a melted connector at the bulkhead no matter what.
 
If memory serves me, the group of wires that attach to top of the heater box (resistor block) also contains a long brown wire that goes to right kick pad as a ground.
 
NoahSewal said:
and replaced the carpet.
Click to expand...

66Valiant528 said:
I'm going to guess you pinched a wire somewhere.
Click to expand...

Probably.

Noah, remove the driver side kick panel, behind it you should see a set of wires with a connector. Unplug that connector and put another fuse in and see if it blows.

If it does not blow my guess would be you pinched one of the wires going to the back when you did the carpet and put the sill plate back on.
 
Read post 4. Find out everything on that fuse. Suspect any work that has recently been done.

If thing get "worst" there are tools that can help

One is to "rig" an old stop or backup or dome lamp socket and bulb and clip that across the fuse clips. This will create a resistance that limits current. when the bulb lights, either a load such as heater blower is powered on, or a short is present. This protects the circuit so you can look for it.

There are also various "short finders" These generally consist of a special breaker that operates like a flasher. You put the beaker device in place of the fuse, and it pulses allowing current to flow "controlled." There is a probe/ meter that you move along the various suspect harnesses, and the needle movement from the magnetic field in the shorted wire helps locate the fault. These tools have been around "since I was a kid." I'm 73

kd tools short finder - Google Search

One example

Intermittent Short Indicator & Short Circuit Finder
 
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