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Post by xx2pro4uxx20 on Apr 18, 2021 17:20:08 GMT -5
I'm trying to figure out where the short might be. So right now the entire front end of the car is hot (has positive energy). It becomes hot whenever I turn the key to accessories but it returns to normal whenever I turn the key to start. It also changes (but doesn't return to normal) whenever I adjust either the gauge cluster/headlight brightness dial or whenever I adjust the wiper/washer dial. If you have an idea of what or where it might be then let me know or if you need more information then I can answer any questions you have.
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DynoDave
CO-ADMINISTRATOR
Motown Mopar-Wizard
Posts: 11,163
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Post by DynoDave on Apr 18, 2021 20:05:03 GMT -5
I'm going to create a duplicate quote of your text, and change some of the wording so that I'm sure I'm following what you are saying. Tell me if I have it right. Also, remind us what you have...what model year, engine, trans, etc. Any known modifications to the electrical system? Aftermarket stereo, alarm, fog lights, etc? Note, if you have an electrical short, with power getting to ground, that circuit should be popping it's fuse, or tripping it's circuit breaker if so protected. What are you seeing that makes you believe you have an electrical short? Your original text: I'm trying to figure out where the short might be. So right now the entire front end of the car is hot (has positive energy). It becomes hot whenever I turn the key to accessories but it returns to normal whenever I turn the key to start. It also changes (but doesn't return to normal) whenever I adjust either the gauge cluster/headlight brightness dial or whenever I adjust the wiper/washer dial. If you have an idea of what or where it might be then let me know or if you need more information then I can answer any questions you have. My version of the first part of that: I'm trying to figure out where the short might be......the front of the vehicle has 12 volts when I turn the key to the accessory position, but no voltage when I turn the key to the start position. If I have interpreted that correctly, I'm not seeing the issue (which probably means I did not interpret your comment correctly). There are certain circuits (though not all of them I don't think) that receive power in the accessory position. Things like your radio or fan might work in the accessory position. Other circuits are hot all the time, regardless of the key even being in the ignition. Those would include the horn, lights, etc. With the key in the start position, just about everything will be denied power, to preserve cranking amps for the starter motor. SO if you are noticing that your power windows don't work, fan doesn't work, radio doesn't work when in the crank or start position, I think that's normal. It also changes (but doesn't return to normal) whenever I adjust either the gauge cluster/headlight brightness dial or whenever I adjust the wiper/washer dial. I'm not sure what you are saying here.
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Post by xx2pro4uxx20 on Apr 18, 2021 20:37:43 GMT -5
I'm going to create a duplicate quote of your text, and change some of the wording so that I'm sure I'm following what you are saying. Tell me if I have it right. Also, remind us what you have...what model year, engine, trans, etc. Any known modifications to the electrical system? Aftermarket stereo, alarm, fog lights, etc? Note, if you have an electrical short, with power getting to ground, that circuit should be popping it's fuse, or tripping it's circuit breaker if so protected. What are you seeing that makes you believe you have an electrical short? Your original text: I'm trying to figure out where the short might be. So right now the entire front end of the car is hot (has positive energy). It becomes hot whenever I turn the key to accessories but it returns to normal whenever I turn the key to start. It also changes (but doesn't return to normal) whenever I adjust either the gauge cluster/headlight brightness dial or whenever I adjust the wiper/washer dial. If you have an idea of what or where it might be then let me know or if you need more information then I can answer any questions you have. My version of the first part of that: I'm trying to figure out where the short might be......the front of the vehicle has 12 volts when I turn the key to the accessory position, but no voltage when I turn the key to the start position. If I have interpreted that correctly, I'm not seeing the issue (which probably means I did not interpret your comment correctly). There are certain circuits (though not all of them I don't think) that receive power in the accessory position. Things like your radio or fan might work in the accessory position. Other circuits are hot all the time, regardless of the key even being in the ignition. Those would include the horn, lights, etc. With the key in the start position, just about everything will be denied power, to preserve cranking amps for the starter motor. SO if you are noticing that your power windows don't work, fan doesn't work, radio doesn't work when in the crank or start position, I think that's normal. It also changes (but doesn't return to normal) whenever I adjust either the gauge cluster/headlight brightness dial or whenever I adjust the wiper/washer dial. I'm not sure what you are saying here. Mine is a 1971 SE with the U code 440 and the automatic. I'm thinking that there is a short because I short because I don't think the fire wall is supposed to have positive energy going into it right? Isn't it supposed to be the ground for everything that's bolted on to it?
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Admin
FORUM OWNER
Posts: 6,891
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Post by Admin on Apr 19, 2021 8:33:52 GMT -5
(FYI...I'll give you my thoughts, but I'm not the guru on electrical stuff...that's Nacho's job! Hopefully he'll be along soon.) No, there is current for the whole vehicle going through the bulkhead connector on the firewall. (Assuming you mean there is electrical wiring passing through the firewall with voltage present, not that the sheetmetal firewall itself has voltage present in it). If you are referring to the wiring, this is one place where Ma Mopar was a little late to the party. Generally Chrysler engineering was quite good, and in many cases ahead of it's time. But for whatever reason, long after the rest of the industry had moved from the AMMETER (or amp meter) to the VOLT meter, Chrysler stuck with the ammeter meter. An ammeter have to be inline, between the alternator and the load (the circuits of the car). That means the main power off the back of your alternator goes through the plastic bulkhead connector (large electrical connector below the brake booster) on a rather small electric terminal, flows through the ammeter that you see in your dash, then out to the vehicle. With a Voltmeter instead (like on a Ford or GM or the era), that guage is kind of liek an eyeball just looking at what is going o nin the system, without any actual current flowing through it. Expressed like plumbing, Voltage is electrical "pressure", Amps are the electrical "flow". With a tiny little wire and a big giant cable, both can show 12v, but they cannot both flow the same amount of amps. That's why your whole car is 12v, but different circuits have different amp loads (as seen in the different amperage of fuses used to protect them). FYI...converting from a amp guage to a volt gauge is a popular conversion, so you DON'T have all the vehicle amps flowing through a little connector at the bulkhead, and coming into the interior. One such how-to article is linked below. MOPAR CONNECTION MAGAZINE
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Post by xx2pro4uxx20 on Apr 19, 2021 8:41:09 GMT -5
Oh ok I might do that. And whenever I use like, a voltage tester and I touch it to the firewall itself, it lights up. Or if I touch it to something like the radiator supports or stuff like that.
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Post by 71se3834v on Apr 19, 2021 20:51:09 GMT -5
Oh ok I might do that. And whenever I use like, a voltage tester and I touch it to the firewall itself, it lights up. Or if I touch it to something like the radiator supports or stuff like that. When you touch the firewall where is the other wire of the tester/meter connected to?
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Post by xx2pro4uxx20 on Apr 20, 2021 5:22:55 GMT -5
Oh ok I might do that. And whenever I use like, a voltage tester and I touch it to the firewall itself, it lights up. Or if I touch it to something like the radiator supports or stuff like that. When you touch the firewall where is the other wire of the tester/meter connected to? I have the ground connected to the ground on the engine.
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Post by xx2pro4uxx20 on Apr 20, 2021 6:43:08 GMT -5
The engine seems to be the only thing not with positive energy.
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Post by Nacho-RT74 on Apr 20, 2021 7:46:05 GMT -5
Hi! I'm still trying to understand at this moment what exactly the problem is. But my first coment will be:
YOU DON'T NEED TO CONVERT THE AMMETER TO VOLTIMETER like the Mopar Connection magazine is showing... just make te propper mantenience to the ammeter if needed and some wiring upgrades. soooo let's continue LOL
why you are saying there is a short ? is there something burning ? a short will make to blown fuses on fuse box or, on the worst scenario, blow the fuse link.
with ign switch in OFF the only wires energized on engine bay will be the battery wire to starter motor, the battery wire to starter relay, the fuse link and the red wire running to the firewall ( bulkhead Conector ) cpoming from starter relay stud. If everything is in correct order into the cab, the next wire energized is the black wire between alternator stud and bulkhead conector.
Inside the cab, the wires energized will be the red and black wires arriving to ammeter ( these are the ones coming from the engine bay, described previouslly ), the black wire at lights switch, the ignition swithc red wire and fuse box buss bar on batt side, which feeds throught the fuses, the brakes pedal switch, the dome light, the map light, the glove box light, ignition switch courtesy light flasher ( if equipped ) and the hazzard flasher.
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Post by Nacho-RT74 on Apr 20, 2021 7:55:43 GMT -5
to get power to the engine need to put the key in RUN ( Ign 1 ) position. This will activate the blue wire circuit arriving to the ballast and everything around with same wire... voltage regulator, Ignition module if equipped, alternator brush, choke wire if equipped...
and also the blue wire to the wiper motor, but this don't take action into the engine function.
all this system will be on 12 volts rate ( 11-12V depending on batt conditions and terminals conditions ). COIL will get also voltage at brown wire but since is sourced throught the ballast, will be on 4.5-9 volts rate depending on temperature. The ballast resistor changes the voltage to the coil according to temperature, and coil load request according to Engine RPMs.
when changing to START position on ign switch ( Ign 2 ), the wires being feeded with full 12 volts will be the yellow wire to starter relay and the brown wire arriving to ballast and spliced to the coil. This circuit bypasses the ballast to give full 12 volts to the coil for a faster ignition. The blue circuit will be retro feeded through the ballast from the brown wire to the blue circuit with a decayed voltage ( 4.5-9 volts )
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