This will be a dumb question to the electrical wizards on here, but here goes. When making electrical tests where the ignition needs to be in the "Run" position, does the engine have to be running? Or can you just move the key to the "Run" position?
Ignition switch "Run" position
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Depends what you are testing.
Do you just want to see if a circuit is complete?
Garry in AZ
Building a 9 second Valiant
The run position generally energizes all the circuits in the car, including those required to make the engine run.
When the key is in the run position, all circuits should be energized (with the exception of the "start" circuit which cranks the starter motor). If the car is running, the voltages will generally be a couple of volts higher, but having the engine running doesn't change which circuits are hot.
When the key is in the run position, all circuits should be energized (with the exception of the "start" circuit which cranks the starter motor). If the car is running, the voltages will generally be a couple of volts higher, but having the engine running doesn't change which circuits are hot.
I'm looking to test the dash gauges and the add on gauges. Thanks guys!
67Dart273
Well-Known Member
Some random rumblings
For example if you are testing for spark, you don't want to do so in the "run" position of the key and then crank the engine by jumping the starter relay. This is because the run position powers the coil through the ballast, and when cranking the coil is powered direct to the battery through the keyswitch
So if testing in run, you have the voltage drop of the ballast PLUS the voltage drop the battery will suffer due to the load on the starter. You might conclude wrongly that the ignition system is poor
In "run" the ignition circuits, all the dash circuits, and the voltage regulator and smog devices are all powered, along with all "accessory" loads.
In "accessory" there can be quite a few things........in more modern cars.......that remain UN powered.
In "start" normally, accessories are dropped off, along with some "run" components.
The ignition system in cranking is powered by the brown "bypass" circuit, "IGN2" off the ignition switch. The gauges and warning lamps should go dead while cranking
For example if you are testing for spark, you don't want to do so in the "run" position of the key and then crank the engine by jumping the starter relay. This is because the run position powers the coil through the ballast, and when cranking the coil is powered direct to the battery through the keyswitch
So if testing in run, you have the voltage drop of the ballast PLUS the voltage drop the battery will suffer due to the load on the starter. You might conclude wrongly that the ignition system is poor
In "run" the ignition circuits, all the dash circuits, and the voltage regulator and smog devices are all powered, along with all "accessory" loads.
In "accessory" there can be quite a few things........in more modern cars.......that remain UN powered.
In "start" normally, accessories are dropped off, along with some "run" components.
The ignition system in cranking is powered by the brown "bypass" circuit, "IGN2" off the ignition switch. The gauges and warning lamps should go dead while cranking
Good info as always, 67DART273. We cranked the engine for the first time last weekend and it ran really well, but the dash gauges and add-on oil pressure gauge did not work. Dash lights, new gauge lights, and new radio did work. I want to check the gauges and trace the problem, hence my question about the Run position. Also looking at a digital IVR conversion.
It's a 73 Dart Sport 340. Harness is stock except for aftermarket oil and water gauges, crackedbacks headlight harness and his heavy weight alternator wires. I also removed the ammeter and joined those 2 wires, and added a volt guage.
67Dart273
Well-Known Member
Does anything in the cluster..........which is switched by the keyswitch........work? Such as warning lamp(s)? That would give you a clue what might or might not be getting power. This might help when/ if you get the cluster out
Printed circuit pins repair
And if you are unaware, you can download the 73 shop manual, free, from MyMopar. That manual and several others over there came from a few of the guys right here
Printed circuit pins repair
And if you are unaware, you can download the 73 shop manual, free, from MyMopar. That manual and several others over there came from a few of the guys right here
thanks. Yes, the dash lights work. Seat belt warning is disconnrcted. Oil pressure idiot light was replaced with an aftermarket gauge. Gas gauge does not work. Headlight switch works. Turn signal lights and emergency flashers work. I grounded the dash since it's removed from the dash frame. I have that shop manual. In fact, I printed out the schematic, taped the pages onto a long piece of cardboard, and it's been invaluable. I'll start today checking that round dash plug to make sure all the pins are good, and continuity from their source is good. Plus I got the new IVR yesterday.
67Dart273
Well-Known Member
I'm not sure from your description that you have anything else in the cluster that you can check "by visual" with the ignition switch. Oil warning lamp wouldhave been one
The circuit path "in general." One PC board pin gets 12V "run" from the ignition circuit. Those pins (above article) must be tight or repaired
12V goes on a circuit trace to the gauge limiter. LIMITER CONNECTOR fingers in the pc board can lose connection at the board traces, also detailed in that link
Limiter itself of course can be bad
The gauge stud nuts can become loose/ corroded. Consider replacing gauge nuts with "real" ones, loosen/ tighten a few times to "scrub" the contacts clean
Sender connections run right back to the PC board connector pins, so check for more loose pins
The temp gauge and oil warning senders both run through the bulkhead connector, so check that as well
The fuel gauge runs through the tail harness and the left kick panel connector which is "usually" not a problem but can be
The circuit path "in general." One PC board pin gets 12V "run" from the ignition circuit. Those pins (above article) must be tight or repaired
12V goes on a circuit trace to the gauge limiter. LIMITER CONNECTOR fingers in the pc board can lose connection at the board traces, also detailed in that link
Limiter itself of course can be bad
The gauge stud nuts can become loose/ corroded. Consider replacing gauge nuts with "real" ones, loosen/ tighten a few times to "scrub" the contacts clean
Sender connections run right back to the PC board connector pins, so check for more loose pins
The temp gauge and oil warning senders both run through the bulkhead connector, so check that as well
The fuel gauge runs through the tail harness and the left kick panel connector which is "usually" not a problem but can be
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