74 Duster Electrical

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reefkeeper

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Well I read forums for about 2 hours before deciding to post. Here is the issue.

I have NO power to the fuse block at all. This just started and I think it may be something I did but do not know what it was. I pulled the instrumetn cluster out to replace light bulbs because the dash lights were not working. Not following the 101 for auto electrical I did not disconnect the battery. I think all would have been ok except while wedge under the dash I let my wrench touch the RED terminal of the ampmeter and the frame of the dash. I know...

Ironically with everything put back together I have voltage between the red and black terminals on the ampmeter... but NO power anywhere else in the fuse block. I can also crank the vehicle over... just won't start.

I did replace the ignition switch after this happened as well because I thought maybe I fried it. I read in some of the forums my original "no dash light" issue may be because of the headlight switch.

But I need help getting power back to the fuse block... normally the two fuses on the bottom right have power all the time because I have checked them before while troubleshooting other issues a while back. Now I have no power to them.... and with the ignition turned on I have no power to any of them.

I have a wiring diagram and I am struggling to understand where the fuse block gets it's power from.
 
yeah... have power on both sides of it. Are there more than one? I tested it by sticking the sharp pointed end of the test light through the jacket and had the aligator clip connected to the engine block.
 
another thing I noticed while chasin wires that I did not realize before is that there is no wires connected to the reverse/neutral safety switch. I found the connector the pigtail it is supposed to plug into just hanging down as if it had been removed. The car has functioned like this for several months since I bought it.
 
Changed the ballast resistor this morning just for "grins" as it is a very common failure point within mopars. Bought a new headlamp switch as well and I will install it later today when I have time to pull the instrument cluster.
 
some basic info that may help.
Power comes in the car on the red wire to alt gauge then leave the alt gauge on its black wire. That black wire goes back into the harness where it is bonded to as many as 5 drk. blue wires. One of those goes to the headlight switch, one goes to the hot at all times bar of the fuse box, one goes to ignition switch, etc... Any short or sparks flying on the inside of the firewall is supposed to burn out the fusible link. If the fusible link is still good, I would find the black to blues bond and check backward from there.

And you dont have to pull the cluster to replace the headlight switch but thats a moot point since you have other problems in there.
Good luck
 
I have to agree with redfish. You have a problem either with your fusible link or closer in under the dash. You're looking for an open circuit somewhere so keep poking around. Check your ammeter connections again, make sure they're tight. You should have voltage on both sides of the ammeter. Don't just go replacing parts until you know where the problem is or you'll be wasting your time and money.
 
thanks cuda jim. I will be wedging myself under the dash tonight. I replaced the headlight switch today at lunch but for other reasons. I had no Dash lights which is what sent me down this path to begin with. I am hopeful that when I get everything working again that I will have dash lights too.
 
CUDA JIM... you DA MAN!!!

it was actually something you said that made me realize that I was NOT testing the ampmeter correctly. I was testing it by putting one lead on the black wire and one on the red wire on the back of the ampmeter. This identified that I had power...

However, if I put one lead on a chasis ground and the other on the RED wire I get a good light. If I put one lead on a chasis ground and the other on the BLACK wire... nothing.

So from this I discern that the ampmeter is maybe fried. Not a bad thing because I have another instrument cluster that I can change out the ampmeter from. Or I have a three cluster gauge set mounted below that I can hook the ampmeter leads up to. anyhow... I think this may resolve my issue. I will let you know.

overlooking the simple things can kill you.:munky2:
 
ok... not happy. Did a real quick test by connecting it to the aftermarket gauge cluster I have but have only used for oil pressure and temp. I never hooked up the ampmeter because it was working fine.

anyhow... the test did not go so well. I connected the leads to the other ampmeter and it still did not give me voltage on both sides. Only the red side.

if I take the ampmeter out of the loop by connecting the red and black wires directly together... would that damage anything? I cannot see how but can't hurt to ask.

CUDA JIM still DA MAN for getting me this far.
 
Best plan Put both red and black on the same one post of the amp gauge.
Otherwise you would need a 10-24 screw and nut and tape and well ...
anyway you found it. Happy Moparing
 
ok... so here is where I ended up for now.

connected both the red and black leads to the red terminal on the back of the instrument cluster. I now have power back as I would expect and the same things that worked before... works again. Headlights, turn signals, hazards, fuel gauge, temp gauge, wipers, dome light, etc...

What doesn't work... the dash lights still. When I put a 3amp fuse in the #1 spot in the fuze block it blows it every time. When I got the car it had a 20amp fuse in that spot and I didn't think anything of it. Wondering if maybe that has caused something in the dash to not work correctly.
 
Heres what I suspect... The instrument panel illumination isn't what blows that fuse. Its a bulb socket on the same circuit. The orange wires are the guide. You'll find one at the radio, one at the shift indicater, one at yhe heater control, and probably one in the ashtray hanger. All of those are on the same dimmer reostat.
 
You did the right thing by bypassing the ammeter. I have never seen one blow out but I suppose it can happen.

I am not sure if a 3 amp fuse is adequate for the dash lights or not. Certainly a 20 amp fuse is way too much. If you're constantly blowing fuses then you have to find the short because you're probably grounded somewhere. Get a good schematic out and an ohmmeter. Connect the ohmmeter to the bad circuit and pull things apart until the short goes away. Look at things like the top of the fuse box (pull it down to see) and the light switch and connections to the dash. If you cannot find it you may have a melted wire inside your harness but exhaust all other possibilities first and try to isolate it.
 
here's a new nugget of information.

When I installed the aftermarket stereo I used the cigarette lighter for the "yellow" or always powered connection. And like a bigger fool I found a pigtail hanging near there that tested good for the red "on" only power. Guess what I did!

So here is what I am hoping is the resolve. Maybe as pointed out this pigtail is tied to the dash lights and I used it to power a Kenwood stereo. When my son gets home I will re-wire the stereo the right way.

Shortcuts never turn out good....
 
reefkeeper said:
here's a new nugget of information.

When I installed the aftermarket stereo I used the cigarette lighter for the "yellow" or always powered connection. And like a bigger fool I found a pigtail hanging near there that tested good for the red "on" only power. Guess what I did!

So here is what I am hoping is the resolve. Maybe as pointed out this pigtail is tied to the dash lights and I used it to power a Kenwood stereo. When my son gets home I will re-wire the stereo the right way.

Shortcuts never turn out good....
Click to expand...

That much sounds ok I guess. The cig lighter circuit is a heck of a lot of amps for sterio memory but anyway... the red is radio hot in run so no fault there. The radio also had a orange wire in the same plug with the red that's hot with illumination. The ashtray lamp is on a orange wire too and very suspect. That fixture may have been damaged when the sterio was installed. Hope this helps
 
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