Regulator gone bad?

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70Duster440

70Duster440

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Optima red top battery, (Chrome) Powermaster alternator (despite what others may say about either of these, I've had zero issues over the past few years). Use a battery tender during the winter months. When I built the car I elminated the amp guage and ran power directly from the alternator output to the starter relay lug. Have an Autometer volt gauge now.

Haven't run the car since last Spring. The day I parked it the electronic speedo stopped working and I noticed the volt gauge reading below 12 volts. Some quick checks at the time indicated normal voltage output at the alternator stud and battery. Was a hectic Summer and I finally got around to looking at it again. Battery was dead (8-9v). Because of where the car is stored right now I pulled the battery and alternator. Brought the battery back up and had the alternator bench tested. Everything looked good.

I reinstalled everything and the car starts right up but the speedo is still dead (damn). I really don't want to have to pull and send it in for repairs. A few hours later I return to do a little electrical probing. Car still starts right up but I notice the volt gauge is at 9v and will climb no higher when raising the RPMS.

I'm going to go back tomorrow and check the rest of the charging system but I'm leaning towards a bad regulator at this point. It was one of those reproduction OE units from Mancini.

Think I'm on the right track?
 
First, you need to post exactly what you have. "one of those Mancini reproduction" doesn't tell me a thing. Is this alternator/ regulator wired like the original, or is it a one-wire conversion, or one with the regulator on the alternator??

First thing I'd do is eliminate the battery as a problem, it might be discharged, or have a bad cell. Quickest way out is if you have another vehicle with a known good battery--temporary for testing.

Next, suspect the voltmeter/ or it's wiring. Test right at the battery with a multimeter.

REAL nice lookin' ride, by the way. I like the wheels.
 
It was the 77R06285 or 86 unit shown here. Don't remember which one I bought.
http://chucker54.stores.yahoo.net/volreg.html

Alternator/regulator wiring is original with the exception of the alt output wire as mentioned. Standard, double field wire Mopar style alt.

I'll have to dig up another battery. Yeah, I'll testing back at the battery tomorrow. Only had a test light and not my DVM on hand today.
 
OK, identify the two field leads on the alternator push-on terminals. One is traditionally blue, is "on" with key in run same wire as igntion feed

Leave that one connected, pull the traditionally green wire off at the alternator which goes back to the regulator, and ground it with a clip lead

If the alternator charges "full output" it's in the regulator/ regulator wiring.
 
Full fielded the alternator and verified that it's charging at the battery. Swapped in a spare regulator and now the voltage comes up on the volt gauge in the dash with an increase in RPM's. Cleaned up my ground points on the suspect regulator and it works okay too. I've got between 12 and 13 volts at the battery at idle.

Also took the battery to a battery shop and had them load test it. Passed just fine.

I could get my electronic speedo to "turn on" and work by bringing up the RPM's from idle. As soon as the volt gauge hits 12v or more the speedo turns on and works. If I let the car idle it drops to 10v and the speedo shuts off.

I measure 12+v at the battery feed on the fuse box with the car off. As soon as I start it, it drops below that.

I recall seeing voltages below 12v at idle for the past few years but the speedo continued to work fine. I've got to figure out why and where the drop is occuring. Have already looked at the bulkhead connector.
 
You made a comment, "back at the battery." Is the battery trunk mounted? This could be affecting the charging voltage some.

Also, if the voltage still won't come up with the Optima, it might just be undercharged, unless you're sure you "brought it up."
 
No, battery is in the stock location. I'm going to continue messsing with this but after a full day, it's getting frustrating.
 
At this point I'm gonna give the battery a 2 amp bath with a charger for several hours and see what happens.
 
Our optima on the Jensen required easily 24 hours on a 5 amp battery tender smart charger to get the charger to claim "fully charged".
We have a new tuff stuff 1 wire alternator @ 100 amps or so.
Car batt was dead from sitting a few weeks (left the key in acc).
I jumped the car and drove it for about 30 minutes and the battery was still completely dead. I called optima and complained. They insisted I use a smart charger and let it charge slowly for at least 24 hours. I did, and it is 100 % fixed.
Since then (a year ago) it has sat for a month or more with zero issues. Cranks over like a son of a bich with the original starter.
 
Hmmmm, been charging the battery at 2 amps for the last 48 hours and haven't seen any change in behavior. Spins the starter like crazy but the voltmeter in the run position shows only 10 volts.

At one point, while messing around I had the charger connected and set to 30 amps out. When I turned the key to the run position the voltmeter showed the full 12 volts and my electronic speedo came on - as it should.

I'd think that with a load test at the battery shop, if there was an issue with the battery or if it didn't have a full charge, it would have failed the test.
 
70Duster440 said:
Hmmmm, been charging the battery at 2 amps for the last 48 hours and haven't seen any change in behavior. Spins the starter like crazy but the voltmeter in the run position shows only 10 volts.
Click to expand...

I'd be double--checking that voltmeter with a test meter right at the battery

Hell, even if the alternator is not charging at all, after starting the car, it should run at about 12, more or less, for awhile.

10V is a dead battery. 10V is less than I'd expect to see for CRANKING voltage.
 
I already know I have 12+ volts at the battery (car off or running). I have 12 v on the interior side of the bulkhead connector (car off). I've got a voltage drop somewhere between the bulkhead connector and the gauges. With the car off I get a little less at the battery feed of the fuse box. And even less on the accessory side in the run position. It drops yet another volt there at the fuse box when the car is running.
 
70Duster440 said:
I already know I have 12+ volts at the battery (car off or running). I have 12 v on the interior side of the bulkhead connector (car off). I've got a voltage drop somewhere between the bulkhead connector and the gauges. With the car off I get a little less at the battery feed of the fuse box. And even less on the accessory side in the run position. It drops yet another volt there at the fuse box when the car is running.
Click to expand...

OK, I misread/ misunderstood. My first guess would be problems in the bulkhead connector.

Too bad we aren't within miles of each other. So difficult to "imagine" what's happening.
 
70Duster440 said:
I already know I have 12+ volts at the battery (car off or running). I have 12 v on the interior side of the bulkhead connector (car off). I've got a voltage drop somewhere between the bulkhead connector and the gauges. With the car off I get a little less at the battery feed of the fuse box. And even less on the accessory side in the run position. It drops yet another volt there at the fuse box when the car is running.
Click to expand...

Ok, let's go step by step. Assuming a fully charged battery (12.7v) and an operating charging system.

You say you have 12+v at the interior side of the bulkhead, so there is no large drop through the bulkhead with no load.

You go on to state that there is a voltage drop between the interior side of the bulkhead, and the fuse box feed, even with no load. So you have the first part of your voltage drop there.

Finally, you say there is a 1 volt drop at the fuse box with the car running.

So, someplace between the bulkhead connector and the fuse box, you have a high resistance connection. Most likely the fuse box connection on the main feed from the bulkhead, but it may also be the bulkhead connector. With no load, a crappy connection can measure close to no drop - yet drop a volt or more under load.

Without knowing much about this car, it is hard to diagnose. Is the alternator output stud wired directly to the battery positive? Is there some sort of ammeter bypass done? KOER, you should have 14v or so at the fuse box.

You definitely have a high resistance connection someplace. That type of problem generates heat. The connection will be warm to hot. It will not get better with time - just hotter.

With the engine running, and the battery charging above 13.5v, check the voltage at the starter relay stud on the firewall, and work your way toward the fuse box. You will find it.

B.
 
Thanks. Seems the drop is occuring after the bulkhead. Like I said, I can probe the interior side of the bulkhead and voltages are okay. When I built the car I cleaned the main power terminals and greased everything. I pulled the 3 connectors and reseated them the other day.
 
bohica2xo said:
OkWithout knowing much about this car, it is hard to diagnose. Is the alternator output stud wired directly to the battery positive? Is there some sort of ammeter bypass done? KOER, you should have 14v or so at the fuse box.
Click to expand...

I did do the ammeter bypass. The two ammeter wires were spliced and soldered in the dash harness. There is a wire direct from the alternator output (with fusable link) to the starter relay. Another wire from the relay passes through the original bulkhead fusable link, and through the bulkhead. The original dash harness (red wire) picks it up from there. The return power wire (black) ends on the interior side of the connector - it does not continue on the engine side.

As expected, the voltage comes up inside with a rise in RPM's.

With the engine running, and the battery charging above 13.5v, check the voltage at the starter relay stud on the firewall, and work your way toward the fuse box. You will find it.
Click to expand...

I'll keep looking, guys.
 
Well, that narrows it down quite a bit.

The battery charges straight from the alternator through the termnial at the starter relay. Good.

Your issue is someplace between the connection at the starter relay, and the fuse box. Since the ammeter bypass was done, all of the system power comes through the firewall on one wire.

Check the connections to the OEM fusible link. Check the link too - bend it gently, it should feel like a wire, not a hose full of gravel.

Check the connection at the red wire.

Pull the fuse box loose, and check all of the connections.


B.
 
You have eliminated some of the potential hot spots. I'd concentrate on the ignition switch connector or the switch itself

Check the main power going INTO the switch at the column connector, and the igniton feed coming out.

My wiring is not "pretty." I bought a late model Caravan engine bay relay box, and used the relays / fuses inside for 1 ignition, 2 charging, 3, fuel pump, 4, 5 hi// low beam headlights. This was mated with a "like new" Painless harness I bought used off Craigslist, so now I have a nice clean fusebox. I converted my ammeter to a voltmeter, and eliminated all bulkhead connections except the wiper section, which was OK.

Voltage drop to the regulator is now almost ZERO Thing is bang on 14V, plus or minus temp correction
 
I've printed out another copy of my factory wiring diagram and marked it up with a yellow highlighter to see current paths. I will systematically check the circuits starting at the starter relay, both sides of the fuseable link, etc with current flowing.

67Dart - my eye will be on the ignition switch/connector. I'm drawing power for the speedo from the accessory feed of the fuse box. The other instruments are drawing power from the original cluster harness (G5 - DBL*). Both of these sources come from the ignition switch and both sources have lower voltages than they should.
 
70Duster440 said:
both sources have lower voltages than they should.
Click to expand...

Sounds to me like you are closing in.

You can use the same "voltage drop" checking

Make sure the switch has a load on it "on."

Measure between the battery feed going in and the switch output going out to the load. That will tell you the drop at that point.
 
Here's what I've found so far. I did a few tests with the car running briefly but it's indoors, so rather than gas myself I did them with the key on, engine off. Load would be the dome light, ign. system.

When I began the battery had been on a slow charge for the last 48+ hours. Surface charge was high at the battery but it settled down after a few tests to 12.2v. Optima says is should be between 12.6-12.8v (car off). That concerns me a little. Even batteries measured in a couple of other vehicles were at 12.5-12.6v at rest.

No change at the battery posts with the car idling. Alternator doesn't start charging till RPM's come up to 1200-1500 RPM's or so. At high idle it's 15+ volts.

Voltage drop tests - key on, engine off:

Battery posts: 11.94v
Starter relay: 11.92v
Fusable link connector @ bulkead: 11.88v
Interior side bulkhead: 11.66v
Battery feed at fuse box: 11.42v
Accessory terminals at fuse box: 11.29v
Battery feed at column connector (Red):11.39v
Battery feed after column connector (Red, B4 switch): 11.34v
Return from switch (DBlue, B4 connector): 11.20v
Return from switch (DBlue, after connector): 11.12v

Forgot to measure and note the Black Accessory wire on either side of the connector.

With the column connector disconnected (which essentially removes all loads from the battery with the key on except for the dome light) voltage at the fuse box and connector are very close to battery voltage.

I'm going to run the same tests again after the battery has had a chance to sit to make sure it's holding a charge.
 
Did the volt drop test again. Here are my findings:

Voltage at battery terminals - no load = 12.2v

Key on, headlights on, domelight on (engine not running):

Battery posts: 11.68v
Starter relay: 11.65v
Fusible link connector: 11.58v
Interior side bulkhead: 11.34v
Battery feed at fuse box: 10.9v
Accessory bus at fuse box: 10.8v
Battery feed at column connector (Red): 10.94v
Battery feed after column connector (Red, B4 switch): 10.89v
Return from switch (DBlue, B4 connector): 10.7v
Return from switch (DBlue, after connector): 10.69v
Accessory feed from switch (Blk, B4 connector): 10.85v
Accessory feed from switch (Blk, after connector): 10.85v

I noticed a very slight warming of the connector during these past two tests.

Voltage at battery posts after tests - everything off: 12.06v

After running through the bulkhead, connectors, and switch that's a drop of .88v between the battery terminal and the accessory tap where the speedo is drawing power. And a .99v drop from the battery post to where the balance of the instruments are drawing power.
 
How much of the under-dash harness is original? Even though you have bypassed the ammeter, some of that wiring under the dash is still acting as the battery buss

Your most probable areas are:

recheck the bulkhead connector (interior) on the battery feed

If that's OK, then your most probable are the ammeter/ ammeter connectors (which may be jumpered?)

ALSO there is a great big splice in the ammeter/ battery feed circuit IN THE HARNESS. This is a factory "welded" splice, taped up in there that junctions the ammeter, and the hot feed to the fusebox and ignition switch.

I HAVE FOUND three or four of those which failed over the years.

You are narrowing it down, stay with it.
 
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