71 Satellite ammeter bypass help needed

[71 plymouth]

First thing to do is get a lamp in series with the ground lead of the battery. This will show if the system is drawing current.

Then make SURE EVERYTHING is shut off, check the trunk light, dome light, glove box, ANYTHING, and yank out the cigarette lighter.

Next pull out ALL the fuses

Then jumper around the fuse link. Smart way to do this, until you find the problem, is buy an inline fuse holder and get some 20A fuses

(You'll have to jumper the fuse link to do any testing)

With everything above unhooked, and the light still comes on as Steve says, unhook the main alternator wire.

From there it's a matter of unhooking stuff until you find the problem

Look at the simplified MAD diagram, which represents the "main feed" from the battery, through the bulkhead, and back to the alternator

Look at the diagram below. The battery main feed is represented by the red wire, through the fuse link, through the ammeter, and back out the bulkhead to the alternator

NOTICE the "welded splice". This is a factory splice under the dash, taped up in the harness. You can examine it by untaping from the ammeter, following the black ammeter wire until you get to the splice

This splice supplies UNFUSED power to

the ignition switch

the fuse panel "hot" buss"

the main headlight power (breaker in / on the switch)

the wiper switch on at least some models (breaker on/ in the wiper switch)

Catalog

Also SUSPECT that other wires IN the harness have melted/ welded together. It would be a WISE idea to unwrap the underhood harness if there's evidence that this "came from" the alternator, and certainly do the same with the under -- dash harness

IF you have made changes to the wiring, suspect those. As I said, the ignition feed is NOT fused, is ONLY protected by the fuse link, which will NOT protect the smaller size ignition wires. So if you've added a tach, or changed the ignition system, check that out carefully

Hey guys,
My Dad had a 71 Satellite that I'm trying to keep running. I was hoping to use this upgrade, but I'm hung up on how the wire route changes from the alternator to the battery with my external voltage regulator. In addition to me not being a mechanic or an electrician, I managed to kill my battery before I realized that it wasn't charging, so now I'm beyond figuring it out.
PS The ammeter bypass portion was awesome because my car went from driving down the road to zero electrical power a couple of miles from my house and now at least I could get it up on ramps.

 

[TrailBeast]

If going direct from your alternator output stud to the battery terminal on your relay killed the battery your alternator has at least one bad diode.
Diodes are basically a one direction gate for electricity. (power goes out to the battery when running but not back through the alternator when not)

 

[71 plymouth]

I knew that I didn't make myself clear. I was commuting with it until I had an issue on the way home and suddenly had no power. Jumping and charging the battery had no effect on power to the key, dome light, wipers etc until I did the ammeter bypass, then it would start and run. When I attempted to start it again, it would only rub until I unhooked the battery box

 

[67Dart273]

Well I thought this was supposed to be a new thread but "OK."

First, you can download many years of factory service manuals as well as aftermarket wiring diagrams over at MyMopar for free. Some of these manuals are due to the efforts of the guys right here

Next, Understand a bit about "how it works."

Here's a simplified diagram right from MyMopar

Whether you bypassed the ammeter or not, the "BATT" line at the top of the alternator, in the diagram is your large charging wire, and ends up at the battery. It's possible, due to bad connections, that this has opened up

Now find the "ballast resistor" at middle left of page. The blue labled "ignition1" is the "ignition run" power coming into the engine bay from the ignition switch. Notice that it goes to the alternator field (blue/white) as well as to one terminal of the VR. This is 12V battery power

Last, notice the bottom field connection in the diagram is GREEN and goes only one place........to the VR. This is the wire which the VR uses to control charging........by controlling the "amount of ground" on that field wire.

TO CHECK:

Run engine at fast idle.

Double check battery voltage. If it's below 13, move your meter to the big BATT stud on the alternator. If that is also below 13, it is not charging.

Next, take a "clip lead" and disconnect the green field wire at the alternator. Hook one clip to the alternator field terminal you just disconnected, and ground the other end.

Start the engine, slowly bring up RPM, and watch ammeter/ voltmeter. A charge should be indicated.

If not, shut off engine (for ease) and turn key back on to "run." With your field ground wire still attached, probe the blue field wire at the alternator, still hooked up. You should have "close to battery" at that point

If so, disconnect your ground clip wire, and repeatedly ground/ unground the wire. In subdued light, you should have a small but noticable spark. If NOT, the field is open or the brushes are not making contact.

If you see a spark, there is something else wrong with the alternator, stator, diodes, etc.

++++++++++++++++++++++++++

Now if the above tests DO CAUSE a charge to occur, it's time to examine the VR/ field wiring

Reconnect everything "normal." Now unplug the VR connector. While you are at it, make CERTAIN the VR is tightly grounded. Unbolt it if there's ANY doubt, scrape clean around the bolt holes and firewall, and remount with star lock washers

Now take a clip lead, and "adapt" into the two VR connector terminals. Small screws can be used for this. Jumper across the VR connector.

Now take a clip lead and disconnect the BLUE field wire at the alternator, and ground THAT. Turn the key to "run." Again tap your ground clip wire, and look for a spark. If so, start engine, slowly bring up RPM. If it charges, look over the VR connector for rust/ corrosion, and looseness. Work the connector in/ out of the VR several times to "scrub" the terminals. Again, check the VR for grounding.

Re try? Any charge? If not go buy a new VR

 

[71 plymouth]

I appreciate all of your info. I've been upgrading some of the other wiring as I've come across issues (battery to starter, etc) and I'm trying to make it a dependable daily driver. Thanks again

 

[67Dart273]

You're welcome. Post back here with updates

 

[Mopar Tim]

Well I thought this was supposed to be a new thread but "OK."

First, you can download many years of factory service manuals as well as aftermarket wiring diagrams over at MyMopar for free. Some of these manuals are due to the efforts of the guys right here

Next, Understand a bit about "how it works."

Here's a simplified diagram right from MyMopar

View attachment 1715053991

Whether you bypassed the ammeter or not, the "BATT" line at the top of the alternator, in the diagram is your large charging wire, and ends up at the battery. It's possible, due to bad connections, that this has opened up

Now find the "ballast resistor" at middle left of page. The blue labled "ignition1" is the "ignition run" power coming into the engine bay from the ignition switch. Notice that it goes to the alternator field (blue/white) as well as to one terminal of the VR. This is 12V battery power

Last, notice the bottom field connection in the diagram is GREEN and goes only one place........to the VR. This is the wire which the VR uses to control charging........by controlling the "amount of ground" on that field wire.

TO CHECK:

Run engine at fast idle.

Double check battery voltage. If it's below 13, move your meter to the big BATT stud on the alternator. If that is also below 13, it is not charging.

Next, take a "clip lead" and disconnect the green field wire at the alternator. Hook one clip to the alternator field terminal you just disconnected, and ground the other end.

Start the engine, slowly bring up RPM, and watch ammeter/ voltmeter. A charge should be indicated.

If not, shut off engine (for ease) and turn key back on to "run." With your field ground wire still attached, probe the blue field wire at the alternator, still hooked up. You should have "close to battery" at that point

If so, disconnect your ground clip wire, and repeatedly ground/ unground the wire. In subdued light, you should have a small but noticable spark. If NOT, the field is open or the brushes are not making contact.

If you see a spark, there is something else wrong with the alternator, stator, diodes, etc.

++++++++++++++++++++++++++

Now if the above tests DO CAUSE a charge to occur, it's time to examine the VR/ field wiring

Reconnect everything "normal." Now unplug the VR connector. While you are at it, make CERTAIN the VR is tightly grounded. Unbolt it if there's ANY doubt, scrape clean around the bolt holes and firewall, and remount with star lock washers

Now take a clip lead, and "adapt" into the two VR connector terminals. Small screws can be used for this. Jumper across the VR connector.

Now take a clip lead and disconnect the BLUE field wire at the alternator, and ground THAT. Turn the key to "run." Again tap your ground clip wire, and look for a spark. If so, start engine, slowly bring up RPM. If it charges, look over the VR connector for rust/ corrosion, and looseness. Work the connector in/ out of the VR several times to "scrub" the terminals. Again, check the VR for grounding.

Re try? Any charge? If not go buy a new VR

Good info. Should be a "sticky"

 

[71 plymouth]

Now I'm real lost. I ran the charging bypass from the alternator output to the starter relay without disconnecting the original charging wires (only bypassing the ammeter) and no joy. It'll start with a fully charged battery, but the volts at the output, starter relay and battery begin at 11.8 and drops. In the last 2 years, I've replaced the alternator, voltage regulator, ballast resistor, etc so I was wondering if I could have more degraded wiring issues that I should check before I replace the alternator again

 

[67Dart273]

Check for a charging issue. I tend to divide the system into categories, not in any order


1....Field wiring issues

2....Output wiring issues

3....Components IE regulator and alternator

4....and possibly misc like loose belts, etc

A: To check the system, first make absolutely certain it is not charging. Run the engine at fast idle, and check battery voltage and then check voltage at the alternator stud. If both points are below say, 13.5 it is not charging "much." If it is below 12.6 it is not charging at all

B: The alternator has two field connections. One receives 12V "in run" from ignition switch, the green goes back to the regulator which "controls the ground" of the greenwire

With key on, engine off, see if you have 12V on blue field wire. Check this without disconnecting from alternator. If you cannot reach itwith a probe, switch the blue and green wires

Pull the green off and touch it back to the terminal. You should see a small spark

Take an alligator clip lead and ground the alternator terminal from which you disconnected the green. Start engine, bring up RPM, and see if battery voltage starts to rise. If so it is charging, if not you have an alternator problem

If no charge double check that the blue field wire does have 12V from switch when in "run"

If that works, move to regulator side of system. Still might be wiring

Remove blue field wire from alternator, ground that alternator terminal. Remove connector from VR, bypass the two terminals at the plug and see if it charges. If so, replace the VR, but FIRST make CERTAIN the VR is grounded. Scrape around the bolt holes and firewall, and use star lock washers

These are a simple system:

The VR MUST be grounded
It gets power from the blue
It controls charging by grounding the green

The alternator field gets 12V from blue
Green mentioned above.

 

[BillGrissom]

If the ammeter was working, then bypassing it will not affect the charging. As mentioned, if the alternator diodes are bad, they can discharge the battery while sitting overnight, either way. If you aren't charging, the problem is on the voltage regulator and field wiring side. Many posts here on that. Get a cheap cigarette-lighter voltmeter ($5 at HF). You should measure >13 V when driving, and 12.6 V with engine off if the battery is fully charged.

The best way to bypass the cabin-ammeter run depends on the engine. If a small-block (most 71 Satellites?), grab the alternator cable from a junkyard Magnum V-8 engine (19990-2000's Dodge truck or Jeep GC). That cable runs from the alternator big stud across the timing cover to the battery. I put one on my 1965 Dart w/ 273 engine.

 

[71 plymouth]

Thanks again, I'll chase those wires first

Check for a charging issue. I tend to divide the system into categories, not in any order


1....Field wiring issues

2....Output wiring issues

3....Components IE regulator and alternator

4....and possibly misc like loose belts, etc

A: To check the system, first make absolutely certain it is not charging. Run the engine at fast idle, and check battery voltage and then check voltage at the alternator stud. If both points are below say, 13.5 it is not charging "much." If it is below 12.6 it is not charging at all

B: The alternator has two field connections. One receives 12V "in run" from ignition switch, the green goes back to the regulator which "controls the ground" of the greenwire

With key on, engine off, see if you have 12V on blue field wire. Check this without disconnecting from alternator. If you cannot reach itwith a probe, switch the blue and green wires

Pull the green off and touch it back to the terminal. You should see a small spark

Take an alligator clip lead and ground the alternator terminal from which you disconnected the green. Start engine, bring up RPM, and see if battery voltage starts to rise. If so it is charging, if not you have an alternator problem

If no charge double check that the blue field wire does have 12V from switch when in "run"

If that works, move to regulator side of system. Still might be wiring

Remove blue field wire from alternator, ground that alternator terminal. Remove connector from VR, bypass the two terminals at the plug and see if it charges. If so, replace the VR, but FIRST make CERTAIN the VR is grounded. Scrape around the bolt holes and firewall, and use star lock washers

These are a simple system:

The VR MUST be grounded
It gets power from the blue
It controls charging by grounding the green

The alternator field gets 12V from blue
Green mentioned above.

 

[71 plymouth]

None of my gauges have worked since I got the car 2 years ago, except the speedometer. I've just been using a cheap multi-meter to read the connections in my driveway. Once the wiring is working, I plan to reconnect the aftermarket voltmeter and oil pressure gauges that my Dad had installed.
Yes, small block, 318. I bought 10 gauge wire and inline fuse to run it to the starter relay and also tried direct to battery, but still never broke 12 volts

If the ammeter was working, then bypassing it will not affect the charging. As mentioned, if the alternator diodes are bad, they can discharge the battery while sitting overnight, either way. If you aren't charging, the problem is on the voltage regulator and field wiring side. Many posts here on that. Get a cheap cigarette-lighter voltmeter ($5 at HF). You should measure >13 V when driving, and 12.6 V with engine off if the battery is fully charged.

The best way to bypass the cabin-ammeter run depends on the engine. If a small-block (most 71 Satellites?), grab the alternator cable from a junkyard Magnum V-8 engine (19990-2000's Dodge truck or Jeep GC). That cable runs from the alternator big stud across the timing cover to the battery. I put one on my 1965 Dart w/ 273 engine.