Voltage drop with when ignition on

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First Car 75 Duster

First Car 75 Duster

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Bakersfield
No idea when it started. I parked it 6 months ago to pull the power steering gear box and rebuild it to stop a leak. It turned into a fiasco with a broken header stud and I had to pull the head. Fast forward later. Got the car started and idles and runs fine, "Cool time to put the Holley Sniper on." Got it almost finished up when I'm just looking for a 12v ignition switch that stays on before, during and after cranking when I found that wires that are supposed to be 12v or now at 9.8. Que a storm of the loudest f-bomb I can muster. I have no idea what my next move should be.
 
There really is "no such" ignition switch. If you are using an ignition system that does NOT use a ballast, you can jumper the IGN1 and IGN2 feeds together. In the engine bay, this amounts to the "ignition run" feed that went originally to the ballast--and this also branches off to the alternator field, VR IGN terminal, and other 12V loads in the engine bay such as electric choke. IGN1 "run" GOES DEAD during cranking, and ignition power during cranking is supplied by the IGN2 contact, which jumpers full power to the coil That was normally brown and fed the coil+ side of the ballast resistor.

IF YOU are getting low voltage to the "run" line with the key in "run" one solution is to electrically cut the "run" line soon after it comes into the bay. Used the bulkhead connector end to trigger a relay, feed the relay 12V off the starter relay "big stud" and connect the engine bay end of the "run" line to the switched contact of the relay

The normal "path" for the run line is battery............starter relay.........fuse link.........bulkhead connector..........ignition switch connector..........through the switch.........back out the switch connector on the "run" line..........back through the bulkhead connector..........and branch off to the underhoold "run" loads

EACH OF those terminal points as well as the switch contacts are a potential trouble spot for "drop."
 
Here is a "poorly done" not very hi rez copy of the wiring from the 75 factory manual.
 

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67Dart273 said:
There really is "no such" ignition switch. If you are using an ignition system that does NOT use a ballast, you can jumper the IGN1 and IGN2 feeds together. In the engine bay, this amounts to the "ignition run" feed that went originally to the ballast--and this also branches off to the alternator field, VR IGN terminal, and other 12V loads in the engine bay such as electric choke. IGN1 "run" GOES DEAD during cranking, and ignition power during cranking is supplied by the IGN2 contact, which jumpers full power to the coil That was normally brown and fed the coil+ side of the ballast resistor.

IF YOU are getting low voltage to the "run" line with the key in "run" one solution is to electrically cut the "run" line soon after it comes into the bay. Used the bulkhead connector end to trigger a relay, feed the relay 12V off the starter relay "big stud" and connect the engine bay end of the "run" line to the switched contact of the relay

The normal "path" for the run line is battery............starter relay.........fuse link.........bulkhead connector..........ignition switch connector..........through the switch.........back out the switch connector on the "run" line..........back through the bulkhead connector..........and branch off to the underhoold "run" loads

EACH OF those terminal points as well as the switch contacts are a potential trouble spot for "drop."
Click to expand...
Thank you I will follow some wires till I find the culprit
 
Also if you are unaware, there are 2- page NON factory diagrams over at MyMopar. They leave out options and sometimes connectors and are not depicted quite the same. They CAN however be easier to follow --that is, I often use both
 
First Car 75 Duster said:
when I found that wires that are supposed to be 12v or now at 9.8. Que a storm of the loudest f-bomb I can muster. I have no idea what my next move should be
Click to expand...
what wires did you use? (Where the 9.8v is)

If you took off after the ballast resister that could be the reason for 9.8.
 
There is going to be some voltage drop in the system & the amount will depend on how many components are drawing power through the sw & harness. 9.8v might be 'normal' if components or parts have been added to the electrical system. There could also be some voltage drop from corroded connections.
 
If there is a voltage drop with the ignition on, just drive it with the ignition off and you will have the proper voltage...
 
First Car 75 Duster said:
No idea when it started. I parked it 6 months ago to pull the power steering gear box and rebuild it to stop a leak. It turned into a fiasco with a broken header stud and I had to pull the head. Fast forward later. Got the car started and idles and runs fine, "Cool time to put the Holley Sniper on." Got it almost finished up when I'm just looking for a 12v ignition switch that stays on before, during and after cranking when I found that wires that are supposed to be 12v or now at 9.8. Que a storm of the loudest f-bomb I can muster. I have no idea what my next move should be.
Click to expand...

been a long while ago , but I had to tie 3 wires together on the ign. switch to make my fast 2.0 with an msd work -----------------??

talk to someone that knows more than I do tho...
 
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