Car is a 73 Duster with a stock ignition system. Everything except the wiring harnesses is new (ign switch, module, dual ballast resistor, coil, distributor). With the car not running, but the ign switch in the run position, we have the following. (The Ammeter is bypassed)

Battery positive terminal: 12.20 volts
Under dash bulkhead (blk & red wires): 12.06 volts
Ignition switch connector + in (red wire): 12.01 volts
Ignition switch connector run out (dk bl wire): 11.46 volts
Engine side bulkhead connector (dk bl wire): 11.41 volts
Dk bl into ballast resistor (both circuits): 10.53 volts
Brown wire out of ballast: 3.26 volts
Green wire out of ballast: 10.47 volts
+ side of coil: 3.21 volts

If I disconnect the + wire from the coil (module still connected) I get 11.2 volts at all connectors at the ballast resistor and at the coil.

If I unplug the module (coil connected) I also get 11.2 volts at the ballast resistor and the coil.

Is the drop at the ignition switch too much?

Is the drop caused by the coil and/or the ECM normal?

I assume 3 volts at the coil is too low since the car will not start unless I jump the ballast resistor. Do I have wiring issues?

Thanks in advance for any help.
Ken

The MOPAR setup had long lengths of modest guage wire so voltage drops get pretty high.

On your findings... it sounds like you are testing with engine off?

One comment on the start system. The factory setup has a run position for the key and a start position. With the key turned to start, the coil side of the ballast should be energized with full battery voltage... basically the stock system bypasses the ballast for starting. That's why one side of the ballast has two wires - the second should be the start wire that gives full voltage tot eh coil for starting. You should not have to jump the ballast to get it started. Sounds like something is mixed up in the wiring. One way to test is to remove the solenoid wire from the fender realy so the starter won't engage. Have a helper turn the key to start and check for full voltage at the coil.

Once you get the start sorted out I'd measure voltages with the engine running. First with all lights and accessories turned off then turn them on and check again.

ahy,

Yes, the car was off for the tests. We checked the voltage at the coil with the key on start and got 11.87 vs 12.2 at the battery. About the same drop across the ignition switch as the run circuit.

RapidRobert,

Is the drop from the ignition switch okay? I really don't want to replace it again if I don't have to.

Also, I read somewhere that the volage at the ballast resistor should be within 1 volt of battery. Or is that too much drop?

I also read that something like PPG metal cleaner can be used to clean the terminals. Anyone ever try it?

Thanks again for the help.
Ken

When I've needed to really clean terminals I've used electrical contact cleaner and (carefully) emory cloth. Also check the "clamp" on the female connectors. A very careful squeeze with needle nose pliers can help tighten up the connectors. Follow cleaning with protection. For the bulkhead connector, filling with common grease helps keep corrosion at bay. On others a light coat of grease or at least some WD40 helps.

I think your voltage drops are a bit on the high side but not terrible. Cleaning of the terminals and inspection of the wires should be sufficient to keep it going.

I'd also suggest a voltage test with the engine running. The voltage regulator controls voltage at the "# 1 splice" in the engine compartment. This is close to the circuit that feeds the ignition so engine running will change the differences/drops... probably for the better.

With nearly 12V at the coil with the key in the start position, I would think the car should start. As has been said the key in the start position basically 'jumps' the ballast resistor. How are you actually bypassing the ballast resistor to get a start?

I like to glass bead all my connections and grease em up.

Okay, we were able to spend some time on the car today. We disconnected and cleaned every connection we could find. Even pulled bulkhead out of the firewll and cleaned all of the terminals. It made a big difference. Maybe too much. At every point we tested, the voltage jumps around from about 14-16 volts. We checked at the battery, both sides of the junction block, in and out of the ignition switch, at the blue wire at ballast resistor and at large wire and the blue at the alternator. (The + term on the coil bounced around 7-9 volts)

I don't think it's supposed to jump around like that, right? We checked the green wire at the alternator and it bounced around from about 3 volts to 15 or so. We hooked up a ground wire from the neg batt terminal to the VR and there was no change. We disconnected the plug at the VR and momentarily grounded the green wire. The voltage at the battery started increasing steadily from 15 to about 16 in the 5 or so seconds the wire was grounded. We didn't want to hold it too long but it was pretty evident it would keep climbing.

Does this indicate a bad VR? Or is there something else?

Thanks again for the help.
Ken