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

[AKcharger]

Car idles good in park, also idles good when put in reverse/drive but as soon as the lights are switched on the car misses and dies unless RPM's are kept up. I've cleaned the ground for the voltage regulator, ECU and headlight ground onthe fire wall as well as replacing the voltage regulator...still the same, any ideas?

Thanks

AK

[Chryco Psycho]

carb tuning or vacuum leak , the extra draw from the alt shouldn`t kill the engine

[Plumcrazy]

Put a voltmeter on the battery and see what voltage you're getting there

[AKcharger]

This problem is still vexing me  Checked all grounds, swapped out voltage regulator with a known good one and last night removed alt and tested it at Autozone ®...Checked good.

Alt puts out 15 volts on the car and about 12.5 reaches the Battery. Put lights on Alt still puts out the same but car dies (when in gear).

Thinking out loud here:

- AMP's??? could low amperage cause the problem..Autozones ® tester doesn't check Amps

- I thought about a wire grounding out somewhere causing a problem but that would have blown a fuse

- Bad Ammeter gauge? I'm using the factory gauge but it's working fine and deflects left and right normally

- All visable wiring is tight and looks good

- Voltage Regulator? Swapped that out...but even if I installed a bad one would it really kill the car?

- I'll try enriching the carb mixture as Chryco suggested. I was fiddling with it but I didn't think the alt would pull that much power and stall out the car

- Vacuum...I'm sure it's good, plus when I hit the power brakes (large user of vacuum) that has no effect so I'm discounting that ave.

- Also not only headlights cause the problem but lots of electrical power stuff on...especially when car is at operating temperature and running a while. For example I was backing up in the gargage and car was stalling. Realized I had stereo on and brake lights. Turned off stereo and backed up fine...no stalling problem

Guys....I'm open to any suggestions. Anyone hear of anything like this before???

[71_deputy]

to me it sounds like you have a bad connection somewhere.

the volts at the alt should be the same at the battery- within a volt or so- 3.5 volts different is telling me that there is a problem.   check the bulkhead connections for the power wires and the ing. wire feeding the ing.system.

next- what is the fusable link look like??? look at the outside covering- does it look like it is burnt, plastic wavy? it maynot pass enought current to operate the whole system- but enought to allow you to start the car and run it and no acc.'s running.

what is the rpm's at idle??? if it is less than about 8-900- then the alt will not generate lots of power until the rpm's get up past around 1000-1100.

John Mac

[Plumcrazy]

Just for the heck of it I'd have the battery tested.

[AKcharger]

Hmmm fuseable link...well I'll try anything..I'll go take a look, thanks Deputy.

Batt is only 3 months old and is strong. At least it sits all week and cranks every Friday for work (drive it once a week...wether it needs it or not)

[71_deputy]

10-4  what you are looking for is a weak spot in the system- burnt, discolored wires or connectors!!!!!

[NHCharger]

Had the same problem when I bought my 71 about 10 years ago. One of the wires running from the alternator was damaged. Out of the approximately 16 strands of wire in the cable, only 3 or 4 were still good. So everytime I turned on something that used a lot of juice (like the headlights) the car would die.

[AKcharger]

OK played with car for about 6 hours today with no success...here's what we did

- Shot power from Alt all the way up to bulkhead connector..about 15 volts

- Shot power coming out of bulkhead connector ar Fuseable Link (FL) was down to 13 volts...would seem like problem is inside the car

- 13.4 volts going in to Ammeter and 13.4 comming out ( I thought that might have been bad)

- Systimaticlly disconnected everything in the hopes of removing whatever was causing the resistance...NOTHING

- Harness under the dash is new and unmolested, no bad wires

- If we isolated either the tail lights, brakelights or headlights problem went away. I thought we had it licked when we disconnected the wafer plug at the drivers kick panel and problem went away but that was just 2 hours of chasing our tail..It seems to be a current draw problem not a bad ground/short problem

- Took another voltage regulator and a new Alt of my '72. The new Alt was actually worse and would stumble and try to stall with car in park and RPM's highter!

- Checked for bad gounds on everything...nothing 

NH, tell me more about those bad wires...

AK

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[71_deputy]

two things come to mind here.

one- there is a splice in the harness in the dash- this feeds the headlights and to the ing.switch. it is a chrimp type of connection- factory did this- don't know about repo's!!! 

second.... the connection at the bulk head harness is bad- like it dosen't have a GOOD connection to the engine harnees/ or  harness to the battery.

any bad connection can cause it to drop several volts, this will cause some heating of the wires/connectors.

hint- do you know ayone with a infrared / remote temperature reading device??? pointing the puppy as the system is running will pinpoint a reading higher along a cable that's causing a heat point- tada- problem found!!!

[NHCharger]

NH, tell me more about those bad wires...

AK

Sorry AK, it was so long ago I can't remember. Trying to think back it's also possible that it was the ground from the battery to the engine that had the broken wires. I do remember I couldn't figure it out and had to have my mechanic find it for me.

[AKcharger]

- NH, We tried that, ohmed the batt ground wire...checked good as was ground at the block itself.

- 71, I'm following with ya'. We pulled the plugs at the bulkhead and all the connections were clean and tight. The actual bulkhead block was part of the new (5 years) wire harness so it is in good shape.

- That splice on the cockpit side of the bulkhead is indeed suspect but we couldn't find it since the bundle is so think. At 1st I thought "no way it could be splice since the harness is "new" but if there is one thing I've learned on this car is "new" or "rebuild" doesn't guarentee anything...that temp gun is a brillent idea! just need to find one

Thanks for following this guys.....

[71_deputy]

10-4  looks like a tough one to find!!

[Nacho-RT74]

I'm agree on what 71deputy is saying.

Do you have the same problem when you turn on the A/C or Heater ?

I ask this becasue all accesories runs by ignition switch and lightning net Doesn't, just runs directly from charging system line with a direct wire from the splice mentioned. The blower is the electric device with higher consumption on the car. My thoughts is if you don't have problem when you turn on the blower, then the problem could it be on lightning system, starting with lights switch.

That splice comes from the bulkhead cavity of the Alternator wire and runs up ammeter, so isn't really hard to find.

You could try this to discard or not the splice: remove the black wire of alternator from cavity and runs a separate one from bulkhead up to ammeter ( black side stud ). From ammeter ( same stud )feed the ignition switch on red wire prong ( of course, remove also the red wire on ignition switch plug ). and start the engine... be sure you have tighten the nut stud on ammeter. Check on batt.

With this step you are bypassing the splice stuff and just running the engine, no any device connected on battery side of fuse box or lightning net.

if you get good juice at batt then next step is FEED DIRECTLY FROM AMM STUD the lights switch. It is also a heavy black wire what runs up to switch and make a new test without lights first and then with lights on.

You can do the same with batt side of fuse box after or before that.

Sounds hard but really is easy to do this.

[AKcharger]

Thanks for the tip Nacho

Reading your suggestion it sounds like I'd have to cut into the bundle at the black wire to by pass everything...so I'd still have to find the splice to see where the problem is...I may take that route as a last resort.

I played with it again tonight with not much success. put the old alt back in and changed out all the brake light bulbs in case they were internally shorted. The extra frustrating part is it is not constant. For about 10 min I could put it in gear turn on all the lights and it would be fine...other times turn on lights and it dies right away.

One thing I keep coming back to is the tail light splice that we played with Monday. (see picture with corrosion) as I was cleaning out the trunk with the radio on I hit the splice and the radio went out.It came back on in a minute hit it again and it went out again...this must be it!!! Well, I restripped the wires respiced them again and it was worse than ever (but wires were short and simply twisted). Made wires a bit longer with tighter twists and...about the same sometimes it was good, some times it would die...no difference

I might just wait till something catches on fire...at least then I'd know where the probelm was!

[Nacho-RT74]

ok, then as we have supossing is apparently on lighning net.

what  I was saying is not hard, just running a parallel wire from bulkhead up to ammeter and then from there to ignition switch and anywhere. you need just remove terminals from bulkhead/plugs to be able to reconnect everything.

[AKcharger]

OK I'm with ya', let me take a look at that tonight!

[Plumcrazy]

You might want to retest the circuits that you checked with an ohmmeter using the voltage drop method using a voltmeter.

Ohmmeters don't test the circuit under actual operating conditions. Here's an example.

Lets say you suspect high resistance between point A and point B in a circuit that draws several amps.  The wire has 20 strands in it but 18 of them are broken.  An ohmmeter will show low resistance because it sends a very tiny amount of current through the wire.

But if you take a voltmeter and test between points A and B with the circuit operating it will probably show several volts on the voltmeter.
That is how much voltage you are losing by trying to push a lot of current through a couple strands of wire.  A reading of .5 volts or less is reasonable in most circuits.  The thing to remember is that the circuit must be operating.

[AKcharger]

so it's like a poor man's  way to check amperage? Makes sense. Car is on hold till the weekend then I'll play with it again...leave next week for Kansas show so hope to get it fixed by then...or I'll just drive without headlights

[Plumcrazy]

so it's like a poor man's   way to check amperage? Makes sense. Car is on hold till the weekend then I'll play with it again...leave next week for Kansas show so hope to get it fixed by then...or I'll just drive without headlights

You're not checking amperage, you are checking resistance.
For example, If you have a good battery cable to the starter and put your voltmeter between the battery post and the large post on the starter.  You should see a low volt reading on the voltmeter when cranking even though a large amount of current is flowing through the cable.

[AKcharger]

Well, now it's not doing it? After I fiddled with all the stuff above the problem was still there, then I drove 3200 miles to Kansas and back and during the trip and ever since I've had no problems at all. I'm almost mad the problem cleared up on it's own because that means is it could come back as quickly as it vanished...Perhaps I should change the car's name to "Christine"

Thanks for all the suggestions though guys!

[Ghoste]

Sometimes it's just the driving.  I make a 5 hour (one way) drive to Columbus every summer with the constant running around at the Nats for four days.  My car usually runs its very best when I get to Columbus and when I get home.  As soon as it gets back into the once or twice a week around town gig, little problems seem to crop up.
The moral of the story?
DRIVE YOUR CHARGERS!

[cudaken]

 Is your factory Alt gauge still hooked up? When they go bad you lose your power. Now I have had two just died. Just hooked the power to ALT gauge to the power out post and was fine.

Reason I ask, if you have one going bad, but still trying to hang on I would think that maybe it could cause something like you where posting about.

I will add I was getting the creeps reading this posting.

                                             Cuda Ken

[AKcharger]

Ok...it's back. Same problem as 8 years ago. Only difference now is when the car is "cold" it's fine, it only happens when it's been operating for 10+ min. And now I can be driving at highway speed and car will actually "stumble" for a split second when the headlights go on. Here's what's changed since 2005:
- car has been in humidity controlled storage and driven on occasion, last trip was 750 miles in April
- did the famous "headlight mod" last Oct bypassing the ammeter and light switch, worked fine after that and drove it at least 1000 miles since http://www.dodgecharger.com/forum/index.php/topic,168.125.html
- just finished a 1200 mile trip from PA through blue ridge parkway to Florida. Wasn't noticeable at start of trip and now have to do some fancy footwork at traffic lights to keep it from stalling when I hit the brake (lights)

Open to any all suggestions....