HIGH RESISTANCE IN CIRCUIT -- PLEASE HELP!!

Hello All,

I’m having some frustrating issues with electrical / ignition wiring on my 66 Dodge Dart 270 (225) Slant 6. The headlights and dash lights dim at idle and brighten on acceleration as well as varying voltage with acceleration and de-acceleration. After reading quite a few posts here I’ve determined that I have high resistance some where in the circuit.

Regarding the state of things, I’ve replaced the wiring harnesses last year (engine, dash, taillight) with original reconditioned 66 Dodge Dart wiring harnesses including bulk head and fuse box.

Last week, I had to replaced the alternator and regulator and luckily they were both under warrantee from Oreilly’s. I upgraded the regulator to the $50 mechanical one, since I’ve had to replace the solid state ones numerous times. Also, I replaced the starter relay from Oreily’s and a new ballast, headlight and ignition switch from Rock Auto. I have also restored the dash cluster with a new circuit board, new 12-5volt mechanical regulator, reconditioned gauges (temp, fuel, ammeter), and replaced all bulbs. I’ve wired separate grounds for the headlight switch, dash cluster, and ignition switch as well as for the fuel tank.

The BIG question is where and how to track down the high resistance in the circuit without ripping out the harnesses again? Is it possible, that the alternator and regulator are defective – they’ve been in the car a week? Also, this problem existed with the old harnesses, but it was way more extreme. I should also mention that in the last three years I’ve installed remanufactured alternators from Oreily’s – probably four or five in three years.

Below are voltage tests that I performed this morning with my multi-meter.

Tests performed with Engine running at idle in Park for 20min:
Without load on battery: 14.30v
- Ammeter (Batt) post: 14.25v
- Ammeter (Ignition) post: 14.41v

With load on battery: 12.80v
- Ammeter (Batt) post: 12.45v
- Ammeter (Ignition) post: 12.30v

Tests performed with engine off and ignition switch turned to on:
One probe on positive battery post and other probe on regulator post (Ignition) reads: 1.32v
One probe on positive battery post and other probe on ballast post (Ignition) reads: 1.19v
One probe on positive battery post and other probe on ballast post (Coil) reads: 3.72v
One probe on positive battery post and other probe on alternator post (Ignition) reads: .36v
One probe on positive battery post and other probe on alternator post (FLD) reads: 12.31v
One probe on positive battery post and other probe on starter relay post (Batt): .08v
One probe on Ammeter Post (Batt) and the other probe grounded reads: 12.10v
One probe on Ammeter Post (Ignition) and the other probe grounded reads: 11.97v

Same above tests performed with headlights on:
One probe on positive battery post and other probe on regulator post (ignition) reads: 1.82v
One probe on positive battery post and other probe on ballast post (Ignition) reads: 1.66v
One probe on positive battery post and other probe on ballast post (Coil) reads: 4.14v
One probe on positive battery post and other probe on alternator post (Ignition) reads: 1.02v
One probe on positive battery post and other probe on alternator post (FLD) reads: 12.12v
One probe on positive battery post and other probe on starter relay post (Batt): .40v
One probe on Ammeter Post (Batt) and the other probe grounded reads: 11.40v
One probe on Ammeter Post (Ignition) and the other probe grounded reads: 11.20v

Test performed with engine on at cruising idle:
One probe on negative battery post and one probe on regulator mount (ground): .02v
One probe on negative battery post and other probe on alternator (ground): .01v

Also, I should note that I burned up a solid state 12-5v regulator on the dash cluster yesterday while wiggling wires at the bulkhead (engine was running). This pointed my attention to the factory splice near the ammeter where the headlight / cluster regulator feed are connected to the ignition, but no direct connection to the bulkhead. I'm now back to using a mechanical 12-5v cluster regulator.

If there is anyone who can make sense of all this, I would hugely appreciate it!!
Thanks in advance for any advice, help or guidance in troubleshooting the mess!