fusible links?

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Zinger74

Zinger74

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I have a 74 duster with a slant 6 of course. I went to start it and it was running really rough. I turn on the light and they came on and flickered then both went out. upon turning it off checking the fuses and battery connections, I went to restart it and i have nothing. no turning over or anything. the only way it will turn over is if a use a jumper wire on the starter.I have power to two of the fuses. I was wondering if anyone else has had this problem, and if they know what it was. I was suspecting a fusible link. I checked the one next to the main wiring harness bulkhead on the firewall and I had power on both sides. If anyone knew where the other one is my manual says ther is two. Thanks for any input you have
 
well i checked it and i think it is good i have power on bith sides and i checked it against a new one at napa and it had the same resistance. Becasuse thats what i thought it was.
 
Battery ground seems to be good- check chassis ground, all grounds( voltage reg, relay, dash)
 
Zinger74 said:
well i checked it and i think it is good i have power on bith sides and i checked it against a new one at napa and it had the same resistance. Becasuse thats what i thought it was.
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Checking the resistance on a relay laying on the counter won't tell you whether it is working or not, you need to have power to the relay to see if it is working.

Is your battery fully charged? from what it sounds like it isn't charging and you were running off the battery. Or you have bad connections.
 
i have about 12.5 volts on the battery. And on both sides of the relay. would the starter turn with a jumper wire if the relay was bad? and i havent checked the grounds but it was running before so i assume they are good but i will check in the morning. does anyone think it could be the fusible link?Thanks for the input all the help is greatly appreciated. Im just a young gun trying to learn the tricks of the trade!lol
 
I agree with checking the Body Ground. It will fail without warning. Pull it off of the chassis and clean the spot where it attaches.
Frank
 
74 is the one with a seatbelt interlock i think. it will prevent starting with the key.
 
If the problem is the seatbelt interlock, try to locate an electical connection under the seat on the driver's side. Do the same on the passenger side as well. Disconnect them and see what that does. I know it disables the nagging seat belt buzzer on my 73.
 
Zinger74 said:
i have about 12.5 volts on the battery. And on both sides of the relay.
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What do you mean by both sides? The relay has the large battery cable terminal, the smaller starter cable to activate the starter, the ignition power lead from the switch to activate the the relay which should only have power when you are in the start position and a neutral safety switch wire (on some cars)

Use a test light and see if the ignition wire has power when your switch is in the start position, if it does then ground the neutral safety terminal and try to start it, if it still don't start then I would say the relay is bad.


Zinger74 said:
would the starter turn with a jumper wire if the relay was bad?
does anyone think it could be the fusible link?
Im just a young gun trying to learn the tricks of the trade!lol
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Yes,

If the fusible link was bad, you wouldn't have power to your accessories.

We were all young once and problems like this is how we learned.
 
Well I've checked all of the above. And I still have nothing. Can anyone tell me where the fusible links are so I can check them. And I also buy in another ballast resistor on it and that didn't help.
 
If you have power from the ignition/switch wire at the relay in the start position and the starter turns over when you jump it. The problem has to be the relay, the neutral safety switch wire or a bad connection between the relay and the starter.

1) If your fusible link is bad then you won't have power to any of your assessors so if your radio, interior lights, turn signals and other things work then your fusible link is fine. The fusible link is the wire that comes from the relay and supplys the car with power, usually it has a plastic tag molded into it.

2) double check that you have power at the large terminal of the relay.

3) Is the shifter linkage adjusted correctly? Try and start it but hold the key in the start position while you move the shifter from park to low. If it don't make contact when you do this, then take a piece of wire and bypass the neutral safety wire on the relay, just unplug it and connect the terminal to ground. Then see if it turns over.

If it turns over during that then you know the problem is within your neutral safety switch or shifter linkage.

4) Will it turn over if you jump the two larger terminals on the relay? It should turn over this way even if the relay is bad unless you have a bad wire or connection between the relay and starter.

If still no contact, then you know the problem is between the relay and the starter. but if it turns over there then the problem is the relay.
 
ok well none of my accessories work so i t would be a fusible link. ive checked the resistance across the link and i have no resistance. if it was bad it would read an open. that was the one in the engine compartment next to the master cylinder marked with the tab. my service manual says there should be two. does anyone know were the other one is?
 
Zinger74 said:
ok well none of my accessories work so i t would be a fusible link. ive checked the resistance across the link and i have no resistance. if it was bad it would read an open. that was the one in the engine compartment next to the master cylinder marked with the tab. my service manual says there should be two. does anyone know were the other one is?
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I'm not sure about the 70's Mopars but the 60's A-Bodies only has the one. I'm sure someone on here knows where the other is.

How is the contact between the fusible link at the bulk head connector and the under dash wiring harness? It is common for these connections to get lightly corroded and loose contact.
 
I wish I could help you . You claim there is a second fusible link and I'm not one to argue.
I know the one link at the firewall disconnects everyhing inside the car. If you have power to those fuses hot at all times ( horn and brake lights ) that link is good. The row of fuses hot in run gets its power from the ignition switch. The ignition switch gets its power from the first same fusible link disconnect at the firewall. I would start by locating the ignition switch harness connector exiting the column and use a test light to determine whats hot and whats not in the various switch positions. Hope this helps
 
Ammeter could have died.

If you have a typical A body it probably has a water leak right into the fuse box area too.
 
Wiring diagrams for a 74 Dart and Valiant show only one fusible link in the system. Understand that all of the accesories run off of power that goes through the ignition switch. Follow Redfish's advice and start at the ignition switch and follow the power. If you do not do it systematically you will drive yourself bonkers. www.MyMopar.com has a section devoted to electrical diagrams. If you do not have one in your manual go there and use the Valiant one as a guide.
 
slantzilla said:
Ammeter could have died.

If you have a typical A body it probably has a water leak right into the fuse box area too.
Click to expand...

Back in the 80's my 340 Duster just died. I had all my accessories including lights and could not jump start it. I towed it home and found a large red wire that went from the firewall towards the starter that had a larger diameter in the middle of it. The wire was fatter for an inch or so from what I remember. I believe I was told this was a fusable link back then. It looked burnt. I spliced in another piece of the same gage wire and it started right up.

I don't know if this helps or not but it fixed my problem back then.
 
well it turns out that i traced the wire from the ignition switch and the privios owner removed the fusible link from the wire and used a wire nut to fasten them together. well the wire nut melted and it shorted out. i put a 40 amp fusible link in it and my accesories now work the engine turns over but wont start. i checked all of my fuses and all but one have power. it is in the number one slot and has an orange and brown wire coming from it. the fuse isnt blown but i dont know what circuit this fuse is for. would anyone else happen to know?
 
thats the dash light fuse . It gets power when you pull the headlight switch on..
 
You can't use a fuse to replace the fusible link. You need to replace the fusible link wire with another fusible link wire. The wire is only on the outside of the firewall though and runs between the terminal on the relay and your bulk head connector, the wire on the inside of the car is the main circuit.

The fusible link wire is actually one size smaller than the wire for that circuit, that is how it works, it gives the circuit a week point to burn if you have a short. A fuse will not work because the current in this circuit is not constant because your charging system goes through this wire and will keep blowing a fuse. Especially a 40 amp fuse since most alternators are 60 amp.
 
My brother has been with Bosch and antilock brake controllers since the beginning. I learned from him that there is very little quality control in fuses.
30 amp fuses can carry 50+ amps for .X miliseconds before they blow.
 
Zinger74 said:
And I also buy in another ballast resistor on it and that didn't help.
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Hi Zinger

I thought it's worth mentioning that if the ballast resistor is bad, the motor will crank and crank, but won't start.

Be sure and keep that original (good) one in the car. They can go bad any time, and if you don't have a spare you're stuck.
 
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