65amp wiring/trouble shooting

[SlantedMark4]

Since my amp gauge wires melted a bit I'm thinking about an amp gauge bypass. I still have two wires in good shape from another dash to replace the burnt ones but imo this doesnt solve the problem.
The thing is that I have no idea about electrical stuff at all and I don't wanna burn down my car because of bad wiring and I have not really found out where to start working on the bypass. Can you guys help me? I've also thought about to bring the car to a local classic car mechanic to do the job....
The car has a new Voltage Regulator and new battery btw and if the VIN is correct, there's a 65A Heavy Duty Alternator Option listed if not changed over the years.

 

[Kendog 170]

Here's some reading.
Retrofit AMP meter

 

[Mattax]

First identify and fix the problem.
One common problem on especially in 70s models is a leak: Redfish (who worked at Chrysler dealerships) has mentioned that

[Found!] - Ammeter Gauage for 74 Duster

Hey I am looking for a replacement ammeter gauge for my 74 duster. The current one looks to be in pretty rough shape and melted the plastic between the two posts as well as some pretty heavy corrosion on both post. Already have the gauge cluster apart so hoping to replace it. Picture for reference.

www.forabodiesonly.com

Electrical gremlin

Hey all, I have been trying to determine where my issue is and coming up with no luck. 74 Duster, The car was running the other day, shut it off and when to start it 10 minutes later and I have no power in the car, no dome light nothing. So after an hour of testing under the hood and at the bulk...

www.forabodiesonly.com

A lot of people think the ammeter is the problem. Sometimes they are, but often they are not. When there is excessive current in the battery feed line the connectors got hot, very hot.
In this case the ammeter needle position when it occured and afterwords identifying all the overheated sonnectors will be the clues in tracking down the source of the problem.
Some melted wire connectors shown here, including a ammeter connection which we know exactly why that happened.

If your car has one of the Heavy Duty Alternator options, then yes the wiring for that part of the circuit is a bit different.
One version, '73 B-body with 60 amp Chrysler alternator shown here. Seems similar to the A-body version as documented in the late 60s assmebly drawings.

There was a different version used with rear window defrost grids. How rare is electric rear defrost?

1975 and 1976 each have their own unique wiring for the power feed.

Ignition help needed (stumped)

Hello everyone, looking for some insight. I have a 75 Space Duster 318 i recently aquired and the issue is this. It will not start off they key, infact, key does nothing at the moment. Previous ownser (s) have jumped power to the ballast resistor from power wire off bulkhead . This still does...

www.forabodiesonly.com

 

[Mattax]

The thing is that I have no idea about electrical stuff at all and I don't wanna burn down my car because of bad wiring and I have not really found out where to start working on the bypass

This is an excellent reason not to bypass it.

Here's the basic concept.
Cars have two power sources: Battery & Alternator.
Power flows from whichever one can supply at the higher voltage.
1. Battery can supply power at approximately 12.5 Volts.
2. Alternator can supply power at approximately 14 Volts.
So when the engine is running, the system has14 Volts in it.

The main wire from the battery goes through the ammeter.
The ammeter shows if the battery is discharging or charging. In other words it shows how many electrons are moving into or out of the battery.

The output wire of the alternator joins the battery output/recharge wire on the other side of the ammeter.

On the standard wiring used from 1964-73, the main circuits are all joined at a welded splice (shown as a solid circle in the diagram below).

When the engine is running and the battery is charged, electron flow looks like this.

The ammeter shows zero because the battery is not supplying power, nor is it getting recharged.

Ifthe ammeter stays near either extreme, there is a problem and the engine should be shut off.
The ammeter is calibrated aprroximately 40 amps discharge to 40 amps discharge.

A fusible link in the line helps protect against a short to ground, but will not melt completely at 40 amps. However damage to connectorswill likely occur faily quickly.

 

[RustyRatRod]

I agree with locating and repairing the problem FIRST. That way, you know what's working and possibly what's not. Could be it was just a fluke of a wire rubbing against something through the years and finally got the insulation off and grounded, once repaired, it may never do it again. It all depends on what you want to do with the car. If you're like me and the most you're going to do with the electrical system is a small sound system and electronic ignition, the stock electrical system will be fine, if it's in good shape. Adding electric fans, a lot of tunes and whatnot and you will probably want to make changes like the amp gauge bypass. But unless you repair what's there first, you may end up repeating the problem. That would suck.

 

[4spdragtop]

Each cars wiring issues are unique. I'm not electrically talented, its voodoo to me lol. I did the MAD amp bypass as I was having elec issues and saw the amp gauge flicker a few times(smelled some smoke too).
The bypass may or may not be a benefit to you, but one thing for sure, clean all bulkhead connections thoroughly, and check for melted burnt wires. Our 67 wiring was in good shape, but the insulation was cracking. Harness was 55 years old...I made a new harness, tedious but I enjoyed it.
Heres what I followed for the bypass.
Catalog

 

[Dave999]

if the car is standard and doesn't have
1) electric fuel pump
2) electric fans on the radiator
3) super bass 300watt amp and a sub woofer
4) halogen headlamps
5) kettle for making a cup of tea
6) electric fire for those cold winter days

you get the picture basically stuff that would use way more current than standard

AND you didn't replace the orginal alternator with a 150amp sucker off a modern fuel injected vehicle
and you battery isn't way over spec and constantly half flat.

The wires got hot probably due to resistance of that connector where it goes onto the gauge

in which case
repair wire or its insulation first

clean the connectors, and make sure they go on nice and tight. if they bolt on with a nut use 2 spikey washers and smother the connection with grease

Then i'd go a check my headlamnp switch
and my igntion switch for similar hotness

the issue is really....
They never expected your car to last more than 5 years..
The connectors are exposed to the atmosphere
The connectors are made of a brass type alloy that includes a high % of copper potentially some tin and other metals to make a springly gold coloured alloy for the connectors
these metals when exposed to oxygen and humidity in the air corrode and gets a type of tarnish or rust on them called verdigris
white/green/black dusty tarnish

it doesn't conduct electricity unless its a bit damp meaning the contact patch between male and female parts of the connectors gets smaller and smaller as the greeness spreads into the junction, and a tiny contact patch carrying a high current gets mighty hot
its like you reduced the thickness of the cable at that 1 point down to a size that is trying to burn out under the load.

by cleaning up

1) ammter connector
2) ingnition switch connector
3) bulkhead connector
4) battery clamps
5) both ends of earth strap between body and engine and battery negative and body

you can make an improvment to performance of the car that you feel in the seat of your pants

small brass wire brush
small set of pliers for bending connectors to get better clamping
bag of assorted spikey washers
and a tub of vasaline

will make for a boring but successful weekend of car fixing..

 

[67Dart273]

If you TRULY have a factory 65A option, then part of the problem is "already fixed"

First WHAT ARE WE WORKING ON this is important, what year model?

If you have a 73/ earlier, go to MyMopar and download a factory service manual for free

If you have a 74, contact me about a service manual also for free + a small amount of postage

Start by reading this article:

Catalog

IF YOU REALLY HAVE the 65A factory option, part of your problem is "fixed." This is because the ammeter wires had a "partial" bypass by running the wiring through the firewall with separate grommets, instead of depending on the bulkhead connector.

With a "stock" system the general idea of the problems are this:

1...Generally the wiring for the charging system was simply too darn small for anything larger than a 37--40A alternator
2...The connector terminals in the bulkhead connector were NEVER intended for anything over about 20A and "iffy" at that
3...The ammeter itself can "get loose" and lose connection, generate heat and oxidation and "snowball" (fireball) until it's a total failure
4...Present day folks adding larger alternators to old, ratty wiring PLUS the wiring was never intended for larger ones in the first place, is "guaranteed failure"

IF the wiring is already damaged, you maybe faced AT MINIMUM with pulling the engine bay affected harness out AS WELL as the under-dash harness, unwrapping it, and possibly replacing some wires or at least re-making some connections

You can buy terminals to replace the bulkhead connector terminals.

 

[SlantedMark4]

First identify and fix the problem.
One common problem on especially in 70s models is a leak: Redfish (who worked at Chrysler dealerships) has mentioned that

http://[URL]https://www.forabodieso...r-gauage-for-74-duster.498859/post-1973577130

[/URL]

http://[URL]https://www.forabodiesonly.com/mopar/threads/electrical-gremlin.499116/post-1973580394

[/URL]
A lot of people think the ammeter is the problem. Sometimes they are, but often they are not. When there is excessive current in the battery feed line the connectors got hot, very hot.
In this case the ammeter needle position when it occured and afterwords identifying all the overheated sonnectors will be the clues in tracking down the source of the problem.
Some melted wire connectors shown here, including a ammeter connection which we know exactly why that happened.

If your car has one of the Heavy Duty Alternator options, then yes the wiring for that part of the circuit is a bit different.
One version, '73 B-body with 60 amp Chrysler alternator shown here. Seems similar to the A-body version as documented in the late 60s assmebly drawings.

There was a different version used with rear window defrost grids. How rare is electric rear defrost?

1975 and 1976 each have their own unique wiring for the power feed.

http://[URL]https://www.forabodieso...on-help-needed-stumped.499412/post-1973585053

[/URL]

Thank you very much! This helped me alot man. But there now is a new question. My '74 actually came with a rear window defrost option, so this makes it even more difficult.

 

[SlantedMark4]

This is an excellent reason not to bypass it.

Here's the basic concept.
Cars have two power sources: Battery & Alternator.
Power flows from whichever one can supply at the higher voltage.
1. Battery can supply power at approximately 12.5 Volts.
2. Alternator can supply power at approximately 14 Volts.
So when the engine is running, the system has14 Volts in it.

The main wire from the battery goes through the ammeter.
The ammeter shows if the battery is discharging or charging. In other words it shows how many electrons are moving into or out of the battery.

The output wire of the alternator joins the battery output/recharge wire on the other side of the ammeter.

On the standard wiring used from 1964-73, the main circuits are all joined at a welded splice (shown as a solid circle in the diagram below).

When the engine is running and the battery is charged, electron flow looks like this.
View attachment 1716021338

The ammeter shows zero because the battery is not supplying power, nor is it getting recharged.

Ifthe ammeter stays near either extreme, there is a problem and the engine should be shut off.
The ammeter is calibrated aprroximately 40 amps discharge to 40 amps discharge.

A fusible link in the line helps protect against a short to ground, but will not melt completely at 40 amps. However damage to connectorswill likely occur faily quickly.

Okay, well uhm the thing is I was driving down the highway at around 75mph (speed limit here in Switzerland) when it started to smell badly but it stopped when I pulled over, shut off the engine and started again. It also never smoked again. At home, the battery was overcharged with more than 18V, but the ammeter never went into an extreme (how I remember)

 

[SlantedMark4]

I agree with locating and repairing the problem FIRST. That way, you know what's working and possibly what's not. Could be it was just a fluke of a wire rubbing against something through the years and finally got the insulation off and grounded, once repaired, it may never do it again. It all depends on what you want to do with the car. If you're like me and the most you're going to do with the electrical system is a small sound system and electronic ignition, the stock electrical system will be fine, if it's in good shape. Adding electric fans, a lot of tunes and whatnot and you will probably want to make changes like the amp gauge bypass. But unless you repair what's there first, you may end up repeating the problem. That would suck.

This thing just needs to drive. I've bought it as my first classic car for sunday cruising and car meets, nothing more. There are no modifications planned as such. Maybe a supercharger or so if I'm really bored lmao

 

[SlantedMark4]

If you TRULY have a factory 65A option, then part of the problem is "already fixed"

First WHAT ARE WE WORKING ON this is important, what year model?

If you have a 73/ earlier, go to MyMopar and download a factory service manual for free

If you have a 74, contact me about a service manual also for free + a small amount of postage

Start by reading this article:

http://[URL]http://www.madelectrical.com/electricaltech/amp-gauges.shtml

[/URL]

IF YOU REALLY HAVE the 65A factory option, part of your problem is "fixed." This is because the ammeter wires had a "partial" bypass by running the wiring through the firewall with separate grommets, instead of depending on the bulkhead connector.

With a "stock" system the general idea of the problems are this:

1...Generally the wiring for the charging system was simply too darn small for anything larger than a 37--40A alternator
2...The connector terminals in the bulkhead connector were NEVER intended for anything over about 20A and "iffy" at that
3...The ammeter itself can "get loose" and lose connection, generate heat and oxidation and "snowball" (fireball) until it's a total failure
4...Present day folks adding larger alternators to old, ratty wiring PLUS the wiring was never intended for larger ones in the first place, is "guaranteed failure"

IF the wiring is already damaged, you maybe faced AT MINIMUM with pulling the engine bay affected harness out AS WELL as the under-dash harness, unwrapping it, and possibly replacing some wires or at least re-making some connections

You can buy terminals to replace the bulkhead connector terminals.

It is a '74 Valiant 225, 65A Alternator and Rear Window Defrost option (heard it has different wiring). It looks like none of all the connectors were ever changed or repaired, so those were also never checked I guess... There are also absolutely no modifications.
Everything worked fine until lighting in the dash went off on the left side, then the light switch failed and after all that the smoke came. This all might have the same source.

 

[LO23M8B]

You can't put the smoke back in once it comes out. lol

 

[Mattax]

Thank you very much! This helped me alot man. But there now is a new question. My '74 actually came with a rear window defrost option, so this makes it even more difficult.

The diagram is more difficult but you can spot whether it has the optional setup pretty easily.
On the firewall you should see the grommet with two heavy wires coming through.
Post some photos and we can point it out if its there. We might see other things too

ell uhm the thing is I was driving down the highway at around 75mph (speed limit here in Switzerland) when it started to smell badly but it stopped when I pulled over, shut off the engine and started again. It also never smoked again. At home, the battery was overcharged with more than 18V, but the ammeter never went into an extreme (how I remember)

H'm post some photos of the engine bay firewall, battery and alternator and voltage regulator.

If the ammeter was pointed 1/2 way toward charging, that would be 20 amps.
That's not a problem for a few minutes, but if it continues for long time at 20 or even 10 amps, that indicates a problem.
When its doing that, put a voltmeter across the battery, and if you see 18 Volts you like you did, then problem is probably the regulator.
Confirm its the regulator by measure votlage to ground by probing the connectors closest to the regulator's 'sensing' wire.
On '74 these would be the blue wire feeding the alternator's rotor and connector at the ignition ballast with blue wires.

I can post photos later.

 

[SlantedMark4]

You can't put the smoke back in once it comes out. lol

Lol I mean it didnt start "burning" again lol.

 

[Mattax]

It is a '74 Valiant 225, 65A Alternator and Rear Window Defrost option (heard it has different wiring). It looks like none of all the connectors were ever changed or repaired, so those were also never checked I guess... There are also absolutely no modifications.
Everything worked fine until lighting in the dash went off on the left side, then the light switch failed and after all that the smoke came. This all might have the same source.

One real weakness of these cars is the headlight circuits. The wiring (at least on US models) was intended for 40 Watt headlamps.
When the newer headlamps and replacements came along, they typically draw more power.
You can add a pair of relays and draw power straight from the alternator. This take a big load (9+ amps) off of all of the connections between the alternator and the lamps themselves.

 

[SlantedMark4]

The diagram is more difficult but you can spot whether it has the optional setup pretty easily.
On the firewall you should see the grommet with two heavy wires coming through.
Post some photos and we can point it out if its there. We might see other things too


H'm post some photos of the engine bay firewall, battery and alternator and voltage regulator.

If the ammeter was pointed 1/2 way toward charging, that would be 20 amps.
That's not a problem for a few minutes, but if it continues for long time at 20 or even 10 amps, that indicates a problem.
When its doing that, put a voltmeter across the battery, and if you see 18 Volts you like you did, then problem is probably the regulator.
Confirm its the regulator by measure votlage to ground by probing the connectors closest to the regulator's 'sensing' wire.
On '74 these would be the blue wire feeding the alternator's rotor and connector at the ignition ballast with blue wires.

I can post photos later.

Okay imma gonna take some pics after this text here. After the battery had 18V or more, I've ordered a new regulator and new battery. Me and my father checked again and it didnt go over 15.4V first but when the battery was recharged, it was solid around 14.7-14.9 - as it should be. I have to say the regulator is not an OEM replacement, so this might be another problem for the future.

 

[SlantedMark4]

Here are some pics of the alternator, bulkhead connector, fuselage link and other wiring. I've done absolutely nothing with the wiring so if there's something wrong or messed up, blame the guy I've bought it from lol.
I've only checked the battery cables which look pretty good.

 

[Mattax]

After the battery had 18V or more, I've ordered a new regulator and new battery. Me and my father checked again and it didnt go over 15.4V first but when the battery was recharged, it was solid around 14.7-14.9 - as it should be

it's possible the battery was part of the problem, or the wiring to the voltage regulator from the alternator contributed to the problem.
If there is resistance in the wiring such that the regulator sees voltage lower than the set point, the regulator goes provides constant maximum power to the rotor. The regulator is trying to bring the voltage up because its seeing the voltage as low.

 

[SlantedMark4]

it's possible the battery was part of the problem, or the wiring to the voltage regulator from the alternator contributed to the problem.
If there is resistance in the wiring such that the regulator sees voltage lower than the set point, the regulator goes provides constant maximum power to the rotor. The regulator is trying to bring the voltage up because its seeing the voltage as low.

Is it also possible that just the regulator itself failed? But wouldnt the ammeter get crazy in this scenario?

 

[67Dart273]

The "usual culprits" with overcharge/ over voltage is this:

1...Some rebuilt alternators are incorrectly assembled with one brush/ field connection grounded
2...Rarely, the VR goes bad OR IS NOT GROUNDED
3...More commonly is VOLTAGE DROP. This can happen either on the ground side (VR MUST see a good connection back to battery)
..................OR.............drop in the ignition "run" circuit.

You can check for drop by turning the key to "run" with engine off. Connect your meter to the blue alternator field connection without disconnecting it from the alternator. Stab the other probe into battery + post. You should read very little, the less the better. If you read more than about .3V (3/10 of one volt) you have a problem.

The path and trouble areas are the bulkhead connector, the ignition switch and connector

If you cannot find or fix it, add a relay on the "run" line. Cut the "run" line coming into the engine bay, use the end coming through the bulhkhead connector to trigger the relay, and feed the relay contacts through a fuse/ breaker off your starter relay "big stud." Connect the engine bay end of the cut "run" line to the switched contact

 

[SlantedMark4]

The "usual culprits" with overcharge/ over voltage is this:

1...Some rebuilt alternators are incorrectly assembled with one brush/ field connection grounded
2...Rarely, the VR goes bad OR IS NOT GROUNDED
3...More commonly is VOLTAGE DROP. This can happen either on the ground side (VR MUST see a good connection back to battery)
..................OR.............drop in the ignition "run" circuit.

You can check for drop by turning the key to "run" with engine off. Connect your meter to the blue alternator field connection without disconnecting it from the alternator. Stab the other probe into battery + post. You should read very little, the less the better. If you read more than about .3V (3/10 of one volt) you have a problem.

The path and trouble areas are the bulkhead connector, the ignition switch and connector

If you cannot find or fix it, add a relay on the "run" line. Cut the "run" line coming into the engine bay, use the end coming through the bulhkhead connector to trigger the relay, and feed the relay contacts through a fuse/ breaker off your starter relay "big stud." Connect the engine bay end of the cut "run" line to the switched contact

Okay thank u mate. Imma gonna check it asap and share the results here. You mean the blue line ("run" line) from the ignition switch to VR on the chart @mattex posted on top of this thread, right?

 

[Mattax]

Three connectors and heavy wiring. Likely a heavy duty system. Lets figure it out.
Begining at the battery. Red wire (A1) goes to the starter relay shown here.

We see a junction here with two other wires. One large red wire and the other a black? fusible link.

Next.

Not what we are seeing here a the grommet - Other than its probably to the ammeter. Will come back to this.
We also see a red wire to a connector possibly going to the multiconnector.

Looking at this one we see another red wire and connector that may be going into the multiconnector.

Do you have a picture of the original voltage regulator and connections?

Let me get my dinner cooking and will come back in bit.

 

[Mattax]

It looks like a standard regulator - or at least the wiring is the same as standard.
The blue wire into the regulator is the sensing wire. It is joined with blue wire feeding the rotor.

Measuring voltage at that connection on the alternator will reveal what voltage the regulator beleives the system is at.

Another location is at the ballast resistor. Same circuit and should be the same voltage.

The voltage at the battery, and at the alternator output stud should always be nearly the same.
When the key is switched on the voltage in the 'run circuit' blue wires should also be the same.
If there is a difference, it will be worse when the battery is recharging, the lights are on, or other additional items are turned on.

With your new, fully charged battery, even if there is a problem in the wiring, it will be less severe.

 

[SlantedMark4]

Three connectors and heavy wiring. Likely a heavy duty system. Lets figure it out.
Begining at the battery. Red wire (A1) goes to the starter relay shown here.

View attachment 1716023035
We see a junction here with two other wires. One large red wire and the other a black? fusible link.

Next.
View attachment 1716023029

View attachment 1716023032
Not what we are seeing here a the grommet - Other than its probably to the ammeter. Will come back to this.
We also see a red wire to a connector possibly going to the multicoasdfnnector.
View attachment 1716023033
Looking at this one we see another red wire and connector that may be going into the multiconnector.

Do you have a picture of the original voltage regulator and connections?

Let me get my dinner cooking and will come back in bit.

This is an ammeter cable from another dash I got for replacements. I could just replace the cables, check the alternator as 67Dart273 said before and see if this makes the job...?

This is the original VR