Author Topic: Voltage spike at ballast resistor  (Read 1052 times)

Offline thedarkside

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Voltage spike at ballast resistor
« on: February 20, 2016 - 07:45:13 PM »
Hi all,

The 70 challenger recently lost all spark but after replacing the coil, ballast resistor, and voltage regulator she is back running great. The issue I now have a massive fluctuation in voltage specifically at the ballast resistor feed and coil. It was jumping between 4-16 volts which I know will turn it into a bonfire quickly. I rechecked all my grounds and they all seemed fine. I ran a 10ga fused bypass from the alt to the starter relay which eliminated the spikes from going above 12 volts but I am still seeing rapid fluctuation. I put a multimeter to my ignition connector in the bulkhead and found the red ign wire is at 12v but the brown ign 2 wire is only at 8v. Would the drop in voltage cause the fluctuation? I have steady volts at the battery and starter relay so it seems to be stemming from the bulkhead. Does this seem correct? Im thinking the only way to remedy the issue is by replacing the dash harness with one from MH but I don't really want to drop the funds if chasing a ghost. Another weird issue is that occasionally I will get a little static shock getting out of the car once it is turned off. Im thinking it may all be related and could be a ground issue but after 4 hrs of trying to hunt down problems I am stuck. I appreciate any help. Cheers.




Offline dodj

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Re: Voltage spike at ballast resistor
« Reply #1 on: February 20, 2016 - 07:50:49 PM »
Check the bulkhead connector connections and the column connector - the one with the large size wires. common problem areas. :2cents:
Scott
1973 Challenger  440 4 spd 
2007.5 3500 6.7 Cummins Diesel, Anarchy tuned.
Good friends don't let friends do stupid things. ........alone.

Offline thedarkside

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Re: Voltage spike at ballast resistor
« Reply #2 on: February 20, 2016 - 08:03:47 PM »
Check the bulkhead connector connections and the column connector - the one with the large size wires. common problem areas. :2cents:

I checked the bulkhead and it seemed ok. I guess as good as they can be for the age but no burns or hotspots. The column connector has been replaced with butt connectors because the original connector was toast. I do think the problem is hidden somewhere in there though.

Offline Jefferyfem

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Voltage spike at ballast resistor
« Reply #3 on: March 12, 2016 - 01:38:48 PM »
Thanks Yatzee I didn't realize the voltage bypassed the ballast resistor during the start cycle. I was only using the feed wire for it because it was the closest 12v switch to the MSD. I'll find another.