Voltage Readings on Ballast Resistor Please

[jforest1]

Guys,

73 Cuda 340.

Been pulling my hair out (not really, don't have any) on this problem:
http://www.cuda-challenger.com/cc/index.php?topic=108059.30

Looking to get the DC Volts for the following on the ballast resistor:

During Start and Run positions of the key/ignition:
1a.  During START position, the BROWN Wire
1b.  In the RUN position, the BROWN Wire
2.  In the RUN position, the BLUE Wire/Plug
3.  In the RUN position the GREEN/RED wire

I've tried a couple of ballast resistors now so I need a sanity check.

Thanks ahead of time!

JF

[dodj]

1a - battery voltage
1b - 0 vdc
2 - system regulated voltage - about 13.8 - 14.2vdc
3 - I don't know. If I had a ballast resistor I'd measure it for you, but I have an MSD ignition now.

During start your battery voltage will drop so don't expect 12.5 volts when you are cranking.

[jforest1]

dodj,

The following suggests that 1b would NOT be 0vdc, as 1b would need to feed power to the ignition coil to keep the car running:

Ideally you would have whatever your battery voltage is but there is at best some loss through the wires & connections, should this loss be to great the car will be hard to start. Start the test at the ballast to determine if appropriate voltage is getting to it during Start, for these purposes I'll refer to it as 12VDC... if much less than that you have issues along the way that will need to be addressed.. If appropriate power is getting to the ballast check how much is getting through it. My ballast tested good with no load but was breaking down under load.. Using a multi-meter set to DC, find a solid earth ground & probe the connections while cranking for Start.

here's a good picture http://www.cuda-challenger.com/cc/index.php?topic=73290.msg747450;topicseen#msg747450

dual ballast , (in schematic below the ballast is shown upside down from how the factory installed them) During START the Lower Plug BROWN  should have about 12VDC, When key released goes to RUN the  upper plug BLUE should get 12VDC.
          In the Run position the lower plug GREEN/Red wire should show power reduced to about 5VDC going to the ECU & the lower plug BROWN wire will drop to about 8VDC going to the coil, this is your run power after the resistors drop the voltage

[Bullitt-]

I ask & the only reply i received is below..... it's true newer ECU's only have 4-pins so power to the green/red stripe wire is of no consequence
If you're like me and still have an older 5- pin it would be... I'll get mine back together eventually & record a value..

Does your ECU have 5 pins or 4 , most have 4 & the green wire / dual ballast is not used

[jforest1]

My ECU has 5 pins.

JF

[dodj]

dodj,

The following suggests that 1b would NOT be 0vdc, as 1b would need to feed power to the ignition coil to keep the car running:

You are correct in that the brown will not have 0vdc. I was thinking of power just from the standpoint of the ignition switch witch would be open. But it gets backfed through the ballast resistor from the blue wire, so about 9vdc.
Your diagram says the blue wire has 12vdc in start and run. The blue wire (ignition 1) only has power in the run position.