Electrical gremlin
 

Guys -

OK, the Charger seems to have a new gremlin. The engine is pretty smooth in neutral and drive and through its rpm range. When I turn on the lights, it gets noticeably choppy, like there's a random miss.

What would you suspect (change first)?

1. Voltage regulator
2. Alternator
3. Wiring (ground short, etc ... somewhere)

Anybody see something like this before?

Thanks,

Archer

Alternator testing is free. I would start with a multimeter on the charging circuit. Could even be a bad battery.

eric -

Curious, how a bad battery??? Once the car is running, isn't the ignition system running off the alternator?

The battery does hold a charge really well - and I've stressed it. It's about 2.5 years old.

Will do on the multimeter, next time I can get the car out.

Thanks

Archer

does it do it at idle or through out the rpm range?

A bad battery will not charge and put a huge the strain on the alternator. It acts like a boat anchor. The headlights drain a huge amount of power. Do you use a Battery Tender on it?

Eric -

Haven't used a battery tender. Just heard a lot of pluses and minuses about how helpful they really were. Usually haven't had a problem over the NY winters.

Thanks,
Archer

WHAT YEAR is your vehicle?

DOES IT HAVE the factory style alternator / regulator, or has it been "upgraded" with a Delco, Denzo, "one wire" or some other aftermarket or newer system?


Schedule a day and do some tests

1. Find someone with a REAL (carbon pile) battery load tester, charge the battery up, let it sit at least a couple of hours after charging and have it tested. If you can get the caps off, have it tested with a good hydrometer as well --one with a thermometer

carbon pile load tester:

http://ecx.images-amazon.com/images/...500_AA300_.jpg

hydrometer:

http://www.wirthco.com/images/products/21040_LR.jpg

2 If the battery is OK, make the following test: Turn the key to "run" engine OFF. If you have breaker point ignition, make sure the points are closed. To do that put your voltmeter on the coil neg. terminal to ground. If you read close to battery voltage, they are open. Bump the engine until the voltage goes low

Now, switch your meter to low DC volts, and put one probe on the battery POS post. Put the other probe on the switched "ignition run" wire coming out of the bulkhead, dark blue. This goes to the "key" side of the ballast resistor, the IGN terminal on the regulator, and the blue second field terminal on the 70/ later alternators.

You are measuring, here, the voltage drop from the battery, through the harness, and back out on the IGN run feed. You want to see a very low voltage here, the lower the better. If you see more than .2v (two tenths of a volt) look for problems, anything MORE that that, approaching 1/2 volt or more, get more serious.

The circuit path you are checking above is from the battery -- fuse link -- bulkhead connector -- ammeter circuit -- ignition switch connector -- through the switch and back out -- back out the IGN switch connector (dark blue) -- and back out the bulkhead connector on the dark blue

If the above voltage is high, FIX it. Start with the bulkhead connector, take it apart, clean it, replace bad connectors, or run spliced wire through the connector and simply eliminate the connector on the "large" heavy circuits

READ this excellent article:

(While it used a pickup for a test pig, your charger works exactly the same and suffers some of the same problems)

http://www.madelectrical.com/electri...p-gauges.shtml

which came from this page

http://www.madelectrical.com/

3 If the above checks out, or when you get it fixed, start the engine, run it at an RPM to simulate low/ medium cruise, and warm up the engine and regulator. When the battery is "normalised" (ammeter centered) measure the battery charging voltage. 13.8 -- 14.2 is about optimum. Anything below 13.5 or above 14.5 means trouble, the lower the worse, the higher the worse.

If the voltage is OK, turn on as much "load" as you can, headlights, heater blower, etc. Recheck the voltage. If it goes below 13.5, check the belt tension. Consider having the alternator checked for output. If you get this far, post back as you can make a couple other checks.

DO YOU HAVE a shop manual?

4 Check the GROUND circuit to the regulator. While the engine is running, again put your meter on "low AC volts" Stick one probe on the battery NEG terminal, and the other directly onto the regulator mounting flange. Be sure to stab through any paint, chrome, rust. Again, you are looking for a very low reading, the lower the better. Anything over .2V means the ground is poor. The battery, engine, and body must all be grounded well to each other.


5 The bulkhead connectors along with other wiring problems with connectors and switches are becoming more and more of a chronic problem in these cars as they age. You need to learn how to troubleshoot them, or find someone who does. Consider "doing" the ammeter bypass in the article if need be. Consider installing headlight relays

440 -

OK, thanks, looks like I have some testing to do.

74 Dodge Charger. Very little in the engine bay is stock.

1. The battery was checked out and charged as you described a few weeks ago, when I was having starting problems. The battery was fine and it turned out to be the 30 something year old Orange ignition box - been replaced with a Chrome box.)

2. Electronic ignition and regulator #P-3690731 (Blue box). Voltage jumps, last time I tested it was almost no-existent.

Except for the lights, no load to use! No A/C, no, heater, no radio, just lights. (Used to be a race car ;). )

The regulator is 30+ years old as well, so might just replace that for grins.

Will try the other tests, next decent day and get back.

BTW - this may not be a new problem. There were always times the the engine would be a little rough for no apparent reason. The light thing was pretty obvious last night though.

Thanks!

Archer.

One thing I forgot to mention. Move the connectors in/ out several times to scrub the terminals clean, and "feel" for loose terminal contacts, IE if the connector goes on "to easily." Consider adding "dielectric grease" available at any electrical supply. If you've ever been into modern rigs with rubber sealed connectors, you'll know. Put a considerable amount in the tail/ park light sockets as well

Since you have the later car, you can make the harness test (battery positive, ignition run) by also checking the blue field wire at the alternator. It also hooks to the supply side of the ballast resistor.

I did part of the mad electrical thing. I run a Nippon Denso alternator in my Dart. I bypassed the ampmeter by bolting both of the wires together. Since all my wiring was new from Year One I took the old feed wire coming from the alternator and moved it to the battery. I now have two 12 vdc sources feeding the fusebox.

440 -

Regarding the article on the Ammeter. Any reason way I can't remove the wires from the ammeter and insert a voltmeter inline? Sorta killing two birds with one stone.

Also curious, as to how many people have actually experienced ammeter problems like that? But the way the article was written, seems like it should have been a lot.

Archer

You can bolt the two wires together and use it as the positive reference for the voltmeter and then a good chassis ground for the negative of the voltmeter.

Eric -

Even easier - thanks!

Archer

UH.....actually hooking the voltmeter to the ammeter circuit is not a good idea, unless you use a relay or something, because it will be hot at all times. This will eventually run down the battery in long term stoage.

Best thing is to improve the bulkhead connector situation to where voltage drop is not a problem, and just hook it to the "ignition run" coming out of the ign. switch. This feeds the original dash cluster -- switched voltage to the oil light if used, and to the voltage limiter for the temp/ fuel gauge, so you could tap in there.

440 -

Quick update. Battery, alternator and voltage regulator (replaced) all check out correctly. Bypassed the ammeter, no change. Engine runs fine, even with running lights on. Turn on the head lights (with or without the high beams) and the engine gets a somewhat "regular" hiccup.

What's the next logical step? (I would like to run the car at night...) Just not looking forward to doing a full rewiring job.

Thanks

Archer

Good read at mad electrical about bypassing the amp guage and bulkhead connector I have two wires feeding the 12 volts into my Dart.

http://www.madelectrical.com/electri...p-gauges.shtml

I often reference that article.

Did you perform the harness "voltage drop" test I mentioned earlier? This is really starting to sound like a bad connection in that path

NOTICE in the Mad article posted the "IN HARNESS SPLICE." There has been a number of these BREAK. This splice is taped up, in the under - dash harness, and factory welded, but they DO fail.

The other problem you may have is a bad connection in the bulkhead, either the battery feed or alternator charging line, OR the ignition "run" voltage feed going back out to the IGN system from the IGN switch.

Pull your bulkhead connector apart and inspect the connections

YES these gave trouble "back in the day." My own sixpack RR had problems, and long before Al Gore invented the internet, I pulled apart the melted connector and ran a new charging lead right through it. That car had hang on AC, some amateur radio gear, and the optional 60-65 amp alternator. I also helped some friends, and have MYSELF over the years found 3 or 4 cars with bad "in harness" splices, along with other cars (or pickups) with damaged bulkhead connectors. Up here, in particular, pickups with snow plows (electric/ hydraulic hoist) had melted ammeter and bulkhead problems.

So I would be looking hard at the following:

Bad wiring connectors, broken inside, or loose/ corroded at the alternator, bulkhead, maybe even the ignition switch, and ammeter, and the possibility of a bad under - dash in-harness splice.

To check this splice, you must pull the cluster, and untape the harness. Follow the BLACK ammeter wire, and untape from that wire until you find the splice.

This is not as bad a job as it sounds.

You DO have a service manual, right?

440 -

Thanks again. Rechecked everything. The voltage drop from bat + to the blue side of the ballast resistor is 1.6V. I know that's too high.

The problem is that the bulkhead connector is behind the power booster and the driver's side valve cover. While nothing looks burnt, it is old. Unfortunately, it really can't be reached readily. So, if I have to start removing things to get to it and clean it up, just want to make sure I'm not just spinning my wheels.

Again, without the head lights, the motor is rock solid. Kinda think that if there was some kind of electrical leak, it would be more noticeable all the time.

Archer

Mad electrical also has a spin on rewiring your headlights so they run straight off the battery with relays. This keeps them from drawing voltage through the bulkhead connector. Your old headlight wiring turns on two relays and the relay poles are connected straight to the battery.

Eric -

Here's the problem, the voltage difference with the head lights on vs off is literally in the 10mV range, if even that much.

I figure I gonna have to tear this thing apart sooner or later to get all the gremlins out, I just want to make sure I'm doing the right thing for this current issue first.

Archer

If your wiring is hacked on or it that old either go with the 500 dollar painless wiring kit or you can get the engine forward and underdash for about 700 bucks from Year One. Year one will bring it back to stock appearance.

Eric, 440, et al -

OK, I understand that old wiring in cars or houses is problematic and I figure the Painless wiring kit is going to be my next project, but ...

Here's the part I don't get. If I'm getting a 1.6V voltage leak on the ignition relay, and turing on the head lights, causes minimal if any drain on the charging circuit, then why/how are the headlights causing a noticeable hiccup in the engine performance, basically making it sound like there's a constant electrical misfire. (Yes, it seems that regular.)

That's the part I'm having trouble getting my arms around.

Thanks,

Archer

Your dropping below the 12vdc on the ECU. I run a Summit Box and a MSD box. If you drop below 12vdc on these the same thing will happen. Misfires and sounds like it is cutting out. Have you checked what the voltage is on the run side of the ballast resistor.

Attachment 14697

Any updates Archer?

I would guess Brem is correct. If you don't want to rewire the car, you can "get around" the voltage drop, at least for now, by using at least one relay to supply ignition/ regulator power. Use the blue "run" wire to trigger a relay, and draw the relay contacts power off the big stud on the starter relay.

eric/440 -

Everything I've looked at seems to be within spec, except for getting about a 1.5V drop from the battery + to the blue ballast wire. Nothing looks burnt or corroded.

eric - Voltage on the run side of the resistor is effectively battery voltage (12.7V something cold and about a volt more when running).

Going into the shop tomorrow.

Thanks guys, I'll let you know what happens.

Archer

Guys -

Apparently it's a faulty alternator. Rechecked (and rewired) just about everything on the ignition circuit. No change, ran the car without the alternator circuit and no problems - zero.

(Yes, the alternator was charging the battery, but best we can figure was that the rectifier was flaky - go figure.)

Will replace alternator, hopefully over the weekend.

Thanks,
Archer

THAT is certainly possible. One or more bad diodes will cause uneven AC ripple on the charging/ 12V buss. This is always evident if you have a radio.

440 -

The hardest thing on this car was to "load" the alt. No radio, no heater/blower, nothing, just lights and the wiper motor. We resorted to using the break lights.

Annoying because all the basic tests came back clean.

Thanks again. Hope this works with the new alternator.

Ya know, it's always the last thing you check ... LOL

Archer

Guys -

Two last questions (on this anyway).

1. The current alternator is over 30 years old, and I assume it is a 60 amp, stock model. Since new ones come in versions up to 100 amps, can my old wiring and components handle that much?

Mopar electronic ignition, chrome box, "race" regulator, Accel Super Coil etc.

2. When Diagnosing the problem on Friday, called Accel about the ballast resistors. The said you didn't need the stock dual resistor, only their single one to protect the coil. Didn't make sense to me, so I didn't change that. What's the deal?

Thanks,

Archer