Eng. idles good in "drive" but turn on lights and car dies?...UPDATE!!!

[AKcharger]

OK, this weekend I replaced the rear harness and the Fusible link (which actually was pretty messed up) no changes 

A few of you guys have made credible suggestions that I've yet to act upon, sorry about that...all my idea's aren't working so time to try yours one-by-one 

[Dino]

I would definitely start with the battery.  For the second time now I have been fooled into thinking that a seemingly working battery may actual be the cause of a lot of electrical gremlins. The second time was only yesterday. 

If yours is good it's good but it doesn't hurt to test it out or try another like you said.

It seems that it hardly matters what you activate, the result is he same so it doesn't seem to be a switch.  What are the odds that light, brake, and wiper switch are all bad?

Ground can be a culprit so grab a bunch of test leads and make some temporary grounds.  If the issue is resolved then you can narrow it down.

Have you checked the fuse box?  An issue there can certainly cause something like this to happen.  Check it for wear as well as the power wires and check the main splice.  Have you tried measuring voltage at the fuses while someone turns on the lights for instance just to see if it is stable? 

Have you done anything to the cluster lately?  Are he circuit board pins soldered to the board?  This may be the time to do those little things, upgrade to a solid state voltage limiter if you haven't done so and consider upgrading the charging system.  I didn't try to hide my upgrades but it can be done without being too obvious if you want it so. 

Besides lights, brakes, and wipers, what else makes the car die when switched on?

[AKcharger]

Hi Dino

I'm done throwing parts at it for a bit and will just trouble shoot.

As far as what else causes it to die the above it it, but i don't think there's any other electric stuff left to turn on?

Well vacation this weekend, I'll look at it again next weekend

[74calicharger]

just read through your thread. sound like my issues after i had my engine rebuilt a few years ago. 318 with some internal upgrades but had to pass smog test. so the 318 got a bigger cam up to 214/224 and some headwork done along with 4bbl. after installing new motor idles 800 in nuetral drops to 450-500 in gear. dodges dont like low rpms and electrical draw. i searched as you are looking for a short. found many wires and connectors i thought were the culprit all the while arguing with engine builder and carb shop about what causes that kind of rpm drop. 4 years later when i blew the tranny it turns out my 727 had big torque converter from a truck or something in it. rebuilt the tranny and put in a mopar hipo converter stalls 1800-2300. fixed the rpm drop. idles 850. drops to 700 in gear. no more electrical issues. hope this helps any

[flyinlow]

You said the car runs fine when cold. Does it have a stock choke that keeps the car at a faster idle during warm up ?

A couple ideas:

With a known good ,fully charged, battery in the car. Start the car and let it warm up.

(1) With the car idling jumper from the battery + to the headlight bright light connector at the lamp. All four high beam lamps should light This will put a 20 + amp load on the electrical system without going thru the inside of the car. What happens?

(2) With the car idling jumper from the battery + the ignition. Go in the car and turn on the headlights the normal way or any electric load that would cause the car to quit. What happens?

[AKcharger]

Thanks  for the tip'74 Cali that would be a good direction to go but it's the same even after a Manual transmission swap

Flyin - I did the headlight mod so the headlights are completely powered by the alt via relays so I think this address's your suggestions, that is the power for the headlights does NOT go through the main harness/switch anymore.

[AKcharger]

Here we go...I'm going to go down the list in order till it's fixed, if you think of something I missed please let me know and I'll add it
- Headlight relay mod to bypass main harness
- New Alt
- New ECU
- Another New ECU
- Ballast resistor
- Check/clean all grounds
- Replace Voltage regulator
- Replace ignition Switch
- Replace rear light harness
- Replace Fuseable link
- Check Voltage at coil before/after issue
- Replace Battery
- Bypass Alt gage and run both wires to one stud
- Recheck Alternator wires for broken strands
- Hot wire ignition to test "out of the loop"
- Pull test/inspect all wires
- Check wires with laser temp reader
- Voltage measurements
- Replace Alt with Denso unit

[b5blue]

  I'm still wanting voltage readings at the coil to see if your getting a drop that stalls the car? A before-during-after kinda check. Heck at this point we could be looking at a resistor that needs 10 minutes of run time to get hot enough to be too resistive? (Heat=resistance electrically.) 
  Did you do a tug test on both sides of the wires for bulkhead dash feed and ignition circuits? (Even that is subject to inspection...one part of the crimp holds the conductor and the other part holds the insulator jacket.) I'm thinking of having you run some temporary jumpers here and there like Nacho has suggested just to isolate the issue.
  I'd be BATTY by NOW! Hang in there!       

[fy469rtse]

Just read through this again and again, ?
Even though you will have done bypass shortly, sorry it's one of the main culprits on these cars , yes check and redo all earths , check that it has none missing , rear of engine to firewall , ? Steering column earth , and check all earths in harness , there's a few
Your problem is a resistance build up in bulk head plug and old engine bay wiring , read all your ignition wires go through this plug , re check all connectors in bulk head , clean , crimp , these should be tight, look up the seals hat should be on here, die electric grease is a must ,
Either order new harness for engine bay, or re work your old one one wire at a time , I would be doing it this way just because I would like to find the culprit,
I had a car do similar to me recently,
Turned out it was the battery lead , joint half way under cover, badly soldered joint by Chinese manufacturer, WTF in in a new lead

[myk]

Ugh just replace that 40+ year old wiring and stop pounding your head against the wall...

[AKcharger]

- Blue I changed out voltage check to swapping the coil...my bad That will be next thing I try (list adjusted)
- 469 I'm cleaning checking every ground I come across..but I agree those seem likely. Only parts of the harness now that aren't new is on engine side
- Myk like I told 469 only parts of the harness that aren't new are on the engine bay...we're swappin' 'em out 1 by 1 but my guess is It's not a wire...we'll see 'cause this IS getting fixed this time


...Or I'll have a Killer deal for someone on a '70 4 speed B/O Charger   

[b5blue]

Right we are assuming the coil is crapping out to stall but do not know yet. (Or if so why?) It's the "after about 10 minutes of running" part that bugs me....

[Dino]

I've had coils do exactly that, crap out once they warm up and working again when cold.

[AKcharger]

OK knocked two more things off the list:
- Coil voltage 5.25-5.35 while normal idle and when lights are flicked on drops to 3.45-3.49 till it dies. Not sure what that tells us?
- Installed battery out of the '72, it's 3 months old, no real difference, same thing

In related news:
-- The low beams aren't working now...high beams are fine
-- Fuse blew for instrument lights
-- I really think a big clue is my stereo cutting out. When I switch on items like heater/wipers/washer the car is unaffected AND the stereo is unaffected. BUT anything that effects car like break lights headlights the stereo will cut out. It's wired into the original radio harness.

Next - Crawl under dash, inspect all wires and grounds, replace that instrument fuse and put alt wires on one post...stand by


Here's a video I made so you can see what's up. I could have let the car die but gave it some gas to keep it running...at least it sounds pretty good :-)

[b5blue]

Your ALT gauge drops to drawing off the battery big time? How is the HL mod done?

[AKcharger]

Well I think the draw at idle is somewhat normal with low RPMS...at least that's what I thought  

The Headlight mod, in a nut shell, Runs power from the ALT directly over to headlights bypassing the main harness. The headlight switch controls relays that in turn control the power. Idea is it keeps all that current flow from going in/out the small wires in the dash

[b5blue]

Okay I'm assuming the red wire from the bat. to alt. is the normal exciter circuit? (Stock Alt/wiring.) Your volts are dropping like a rock when that needle swings into the left. Will this stall occur above idle?   

[AKcharger]

No, any RPM above idle and there's no symptoms at all...except the radio cutting off

[b5blue]

  Okay for many years my ALT gauge did something similar, the engine didn't stall but but with the headlights on anything else and the gauge dropped to the left. Blower fan wipers everything at idle ether dimmed or slowed down, the more things on the worse it got.
  My friends Lynn and Steve both own battery and alt./starter shops and spent some time trying to solve what I came to call "lazy idle alt. output". There was no cheap/easy fix. I thoroughly cleaned and went over every connection, raising the idle as much as was tolerable. Getting the vacuum advance working and switching to Firecore wires helped make idle stronger but nothing fixed that low idle alt. output. One thing Steve and I considered was the standard alt test, putting it on a tester machine can't reproduce idle speed for an output test "at idle". (There is no easy way to know the RPM's of the alt. to the RPM's of the engine as a ratio.)
  A few years back I ended up doing the Denso 120 amp conversion as there were really no other options to get +40 amps at idle. (That retain stock wiring the way Mopar did it in 70.) Now it looks like there are many improved systems that don't even need the brackets changed like the Denso did.  The radio clipping may just be the volts dropping momentarily to a point that effects the operation.
 
   

[AKcharger]

OK, I don't want to get too excited but I think I found the problem!!!!! at least for the moment all symptoms are gone, the most telling is the radio, no cut out at all when any lights are turned on. Woo Hoo!!!!!!! 

- Headlight relay mod to bypass main harness
- New Alt
- New ECU
- Another New ECU
- Ballast resistor
- Check/clean all grounds
- Replace Voltage regulator
- Replace ignition Switch
- Replace rear light harness
- Replace Fuseable link
- Check Voltage at coil before/after issue
- Replace Battery
- Bypass Alt gage and run both wires to one stud Ding Ding Ding Ding!!!!!!!!
- Recheck Alternator wires for broken strands
- Hot wire ignition to test "out of the loop"
- Pull test/inspect all wires
- Check wires with laser temp reader
- Voltage measurements
- Replace Alt with Denso unit

[b5blue]

 

[flyinlow]

    For now,  hope it's a   

[b5blue]

New ALT gauge time? 

[AKcharger]

Yup, don't like the idea of it being inop. 

[69wannabe]

Convert that troublesome gauge to a voltmeter and save yourself more troubles in the future. I never chimed in since all the comment's on here had pretty much covered all my suggestions. I just had the voltmeter conversion done on my charger and I feel alot better about it now!!!