Hi guys,

Im rebuilding my 1971 Dodge Challenger. I put in a new dash harness and basically everything in the electrical is new including the ignition switch. I am testing it now and with the ignition off I have power to the coil. Any ideas were I went wrong?

The dash harness is unmodified with the exception of bypassing the amp gauge. The engine harness I modified to not use a ballast resitor so the two leads to the resistor are connected and thats were in getting the power. I am testing so nothing was damaged. Any help would be greatly appreciated.

Thanks
Sanman68

With the engine harness off the terminal with constant power is the dark blue wire on terminal 23.

So the problem is somewhere in the dash area. Everything did work yesterday but now it seems I have a short someplace. I have a digital multimeter and I am measuring voltage on the firewall? I am going to start disconecting plugs and see if can isolate it.

You might get one of those inline pull apart fuse holders with the pigtail on each end & install large clamps on each end then pull a batt cable & connect the fuse holder in series with a 20A fuse to the post and to the removed cable to protect the system as you continue your search. it'll go open if you touch something improper. grab a little tin box of fuses also

Thanks For the tip! The short is somewhere after the black wire on the amp gauge. Im running out of time but im gonna keep chasing it.

take a break/chill for a day/get back after it. I do that on the toughies tho I rarely get bent out of shape over mechanical issues these days (comes with age/experience/mental training). As you know your meter is your best friend right now. Holler what it ends up being.

The black wire goes to 6 spots according to the wiring diagram. One of them being the igntion switch. The short is in or after the igntion switch in the steering column. Thats all im doing today but I did make some progress!

Thanks

The aftermarket ignition switch I bought for my 73(Advance auto) is designed to fit multiple applications and has an extra ground wire in the plug. On my 73, the ignition switch side of that plug was unused. The main dash harness side of that plug however, has two orange wires in it that have power. I had to remove the extra ground wire from the plug and tie it off out of the way. Check to make sure that's not your problem.

You can also take apart the ignition switch connector and test for continuity between the red power "in" wire and the blue "ignition run" wire. You should only have continuity when the key is in the "run" position. That would isolate the switch if that was the issue.

I have a aftermarket ignition switch and I will check that out.

Thanks

What Burdar said, seperate the dangling under the column connector & start ohming (always pull a batt cable off of its battery post before switching the meter to ohms)

Super frustrating few hours with no luck. Ok the short is not with the ignition switch. I am quitting for tonight nothing new to report.

Next spot to look is the key in buzzer.

OK guys,

I should have told more of the story. There is no engine in the car. I am only testing the dash and other harnesses. The car is under construction.

The problem was no dash ground or a poor ground.

I reread your original post, if the coil is hot (positive primary terminal) with key off then either the blue wire ign1 "run" circuit or the brown wire ign2 "crank" circuit is being fed improperly (could be either one cuz you tied em together to bypass the ballast) from the main power in to/thru the ammeter to "welded splice") and further downstream from it to: (ign sw has power all the time as does HL switch & fuse box & horn. the diagrams at www.mymopar.com are fairly accurate (some acc are deleted here and there but its a good site)

https://www.amazon.com/Electronic-Specialties-230-Audible-Trouble/dp/B008LQ61JE

Expensive for this issue only. However a handy electronic troubleshooting tool to have about. Has saved me hours of effort in the past.

Rapid Robert

IT is the blue wire on terminal 23 with power the brown was zero. Again when the dash is grounded they are both zero. Do you think I still have a problems or was it just a ground issue?

the blue and brown should be hot when energized even if the dash ain't grounded & yes you want it grounded well. with the blue/brown tied together is the coil positive primary hot in run and in crank?

The blue wire had power to it with the ignition off. When I attached the ground, the power was off on the blue wire with the ignition off.

Everything is working as it should be now after I grounded the dash.

sumpin ain't kosher, the blue wire should be dead with the ign sw off. with the key on, the blue wire should be energized no matter if the cluster is grounded or not (& yes the cluster needs a good ground) cuz it has to power everything in the blue wire ign 1 run circuit. stay on top of it as you proceed (make that fuse holder) & keep your meter close at hand

Im not 100% sure it is not OK the way that it is. The ground seems to be the main problem. I do agree the blue wire should not have power when the ignition is off and that is how i realized I had a problem. Everything is working now but probably will draw down the battery when i get the rest of the car going. I will find out more once I have everything installed if the car. I wired the car up for no ballast resistor and I will be using a 1 wire alternator running to the post on the starter solenoid.

Sanman68


Without a ground the voltage will find the path of least resistance to ground which can do strange things.