76 dart sport fuseible links

[RevboxRyan]

So I picked up 76 dart sport here a month ago going through trying to figure out wiring harness and other electrical gremlins. All I can find is 75 and older a body diagrams and this one is close but there is stuff not where is supposed to be. And things are hacked and cobbled as usual. Ammeter wires are completely gone fuse box hanging under dash. According to 75 wiring diagram missing a wire to starter relay or is moved to "circuit breaker". Distributor plug for pickup coil is up by alternator list goes on. Anybody have a diagram for a 76 or is 75 exactly the same?

 

[Professor Fate]

Distributor plug up by alternator is probably for 6 cyl. installations.

 

[4spdragtop]

Mymopar.com for manuals. Make sure its oem. Yours looks like a Motors manual.

 

[Mattax]

So I picked up 76 dart sport here a month ago going through trying to figure out wiring harness and other electrical gremlins. All I can find is 75 and older a body diagrams and this one is close but there is stuff not where is supposed to be. And things are hacked and cobbled as usual. Ammeter wires are completely gone fuse box hanging under dash. According to 75 wiring diagram missing a wire to starter relay or is moved to "circuit breaker". Distributor plug for pickup coil is up by alternator list goes on. Anybody have a diagram for a 76 or is 75 exactly the same?

View attachment 1715980173

View attachment 1715980174

Do a search here. One of our members has scanned the electrical diagrams out of the '76 Factory Service Manual. edit Here, see if the pdf is still on the server here. Free service manuals
1976 Electrical System implement a fairly major shift in how the alternator and battery connected to the subcircuits.

First of all, the two power sources are joined at a welded splice in the engine bay.
Instead of one fusible link on the battery ouput/charge line, there is a fusible link on each of the lines joined to it.
Line A3 off the battery is for hazards - which they figure will be critically needed with the engine off.

Here's a work in progress of the main circuits.

Here's a previous discussion about 1976 under hood components
Please Help identifying underhood components

 

[67Dart273]

YOU NEED TO BUY YOURSELF a factory service manual and "I ain't kiddin"

I'm pretty sure 76 HAD NO ammeter wires "as such." I'm pretty sure 76 used an "external shunt" ammeter, meaning, small gauge wires go to a sensitive meter for the ammeter, and they were tapped into points in the main harness, which the HARNESS ITSELF acted as the shunt.

If the car has been "hacked up" enough, someone may have inadvertently disabled the shunt effect.

Just about all vehicles which used ammeters did this at some point--before getting rid of the ammeter per se. Ford, Mopar, GM.

My buddy, now gone, bought a brand new Chev K2500 in 1970--external shunt. The "C barge" Mopars went this route about that time, 70-72.

Look at your ammeter connections at the cluster--small wires? External shunt

 

[Mattax]

Hopefull the mess isn't too deep but hard to know just yet from that photo but ...

Ammeter wires are completely gone fuse box hanging under dash.

H'm. So on a standard '75 wiring, the ammeter is a part of the battery feed to the main splice. So the wiring is heavy - 12 ga or larger.
On a '76 a remote shunted ammeter is used. The ammeter leads connect to each side of a shunt. They are only 18 or 20 gage. Hardly any current goes through them.

According to 75 wiring diagram missing a wire to starter relay or is moved to "circuit breaker"

AFAIK '76 uses esentiually the same starting relay and circuits as earlier and no interlock (used in 74).

A1 is from the battery
S2 is from the ignition switch - hot when key is in start
S4 is the ground through neutral safety switch
S5 is to the solenoid terminal on the starter

Top Cowl - Don't know why its above the flange in 76 but it was.

 

[Tool.Man]

My Dart is a 1976 and has the shunted ammeter. I'm trying to identify the shunt for the ammeter. I see two ballast resistors on the firewall in the photo, above. Is it one of those perhaps?

 

[Mattax]

My Dart is a 1976 and has the shunted ammeter. I'm trying to identify the shunt for the ammeter. I see two ballast resistors on the firewall in the photo, above. Is it one of those perhaps?

No t that easy.
It's in the harness. Specificaly in the battery positive feed.
In the diagram solid round circles represent crimped or welded junctions.

The ballast resistors are in the run circuit.
The one with broiwn wires on the other side is 1/2 oum and connects to the coil.
The other other one should be 5 ohms and helps control powerfor the ECU.
Nothing to do with the ammeter.

There should be three fusible links that are joined together with the battery positive feed/charge wire.
One comes from the alternator output.
One goes to the key switch
The last is to feed all the circuits that do not go through the key switch (headlights, brake lights, dome light, etc)

The other end of the shunt in the factory diagram shows as welded junction. However I don't know exactly where its located in the wire. It might be a ring terminal on the starter relay. Would need to see in person or good photos.

As far as I know the shunt here is simply a wire with a known resistance. Whatever that resistance is, its too low for a normal multimeter to measure.

 

[Tool.Man]

Thanks for helping out.

Here's a few details that might be helpful...
1. I have a first edition of the Electrical Service Manual. Wiring color codes don't match vehicle in many instances.
2. I have the cluster on the bench.
3. The ammeter checks out.
4. Both traces feeding the ammeter were burned in-two. I repaired them. The repair checked good.
5. After repairing the traces I reinstalled the cluster but could not get any movement of the ammeter needle, zero voltage measured.
6. I have voltage from the alternator to ground. This must mean that neither the fusible link nor the shunt are open.

To burn both traces in-two there would have to be a current spike. The only way I can see that happening is the shunt resistance increased. The traces didn't burn in-two a second time because the was no current. All that's left is the harness. If there's a break or a burned connection that would account for no voltage at the ammeter. Let's say I find and fix a problem in the harness. It seems likely I'll burn the traces in-two again...

So I'm confused. I may be way out in left field. Don't hesitate to call BS on any of this.

 

[Mattax]

1. I have a first edition of the Electrical Service Manual. Wiring color codes don't match vehicle in many instances.

All I have is a pdf of most of the diagram pages from a 1976 Dodge or Plymouth Chassis Manual.
I do not know if there were TSBs, but I think I've seen a seperate electric manual but don't have a copy.

2. I have the cluster on the bench

OK. That is helpful to know

3. The ammeter checks out.

How /what did you check ?

4. Both traces feeding the ammeter were burned in-two. I repaired them. The repair checked good.

What sort of check?

5. After repairing the traces I reinstalled the cluster but could not get any movement of the ammeter needle, zero voltage measured.

Lost me here.
With a remote shunted ammeter, current needs to flow through the path parallel to the meter. Voltage on both sides of the meter will be very close to the same.

Need to make a setup where current flows. For example a headlight, three heavy wires (10 or 12 gage) one of which will serve as the shunt. I'm going to guess 12 ga for 15 inches might be ballpark for the shunt. The right thing to do would be to examine the engine harness to get a better idea of what was used.

Then place the ammeter in parallel. Wire gages can be small. I think the FSM showed 20 gage. That helps them act as a safety plus easier to handle.

6. I have voltage from the alternator to ground. This must mean that neither the fusible link nor the shunt are open.

If you are measuring voltage from the Batt (output) stud to ground and the battery is connected, yes the stud should be at battery voltage if there are no breaks in the line. The fusible link grouping on the engine harness is pretty easy to see.

To burn both traces in-two there would have to be a current spike. The only way I can see that happening is the shunt resistance increased.

or one of them touched ground. or as you suggested if there was a break in the shunt connections.

 

[Mattax]

The fusible link grouping on the engine harness is pretty easy to see.

You can see here where the fusible links on DakatoSmith's '76 were located.

Here the are the same off the car. Looks like one is missing.

Here's a snip from the '76 FSM posted by @67Dart273

Read it like this:
A1 is the battery circuit. A1A, A1B, A1C are segments that all connect together.
The diamonds with numbers are junctions.
Between junction 2 and 3 is the ammeter shunt, R6B-8Bk. Alternator Output segment B, 8 gage, Black.

How do we know R6B-8BK acts as the shunt?
Because their is a 20 gage wire from each junction that leads to the ammeter.
A11-20 R*, and R16-20 BK*.

 

[Tool.Man]

3. I put the ammeter in series with a bulb and a 12VDC source just long enough to move the needle on the ammeter.
4. Continuity, measuring from either side of repair.
5. I measured zero voltage at the ammeter to ground.

"or one of them touched ground. or as you suggested if there was a break in the shunt connections." That takes me back to identifying the shunt. A11 and R16 disappear into the harness. It would seem I have to unravel the harness to uncover the opposite ends of A11 and R16. The brake booster will have to come off, too. It's smooth in the way.

I suppose if I do find the opposite ends that there will be a wire between them and that will have to be the shunt. Then, having identified it, I can take the telling measurements. What do you think?

 

[Mattax]

3. I put the ammeter in series with a bulb and a 12VDC source just long enough to move the needle on the ammeter.

Don't think a shunted ammeter can be tested that way. They work more like a voltmeter.
Some other guys here have some experience with them. @67Dart273

4. Continuity, measuring from either side of repair.

Good enough for finding major faults in the connectivity

5. I measured zero voltage at the ammeter to ground.

Then its not connected to the power source.
When the circuit is open downstream, everything above the switch or open should be at the same voltage. In this example, 12.8Volts.

When the circuit is complete, everything before the load should be at the same voltage

the current through the meter itself is milliamps

That takes me back to identifying the shunt. A11 and R16 disappear into the harness. It would seem I have to unravel the harness to uncover the opposite ends of A11 and R16.

Nope. We can use the shop manual.

I suppose if I do find the opposite ends that there will be a wire between them and that will have to be the shunt. Then, having identified it, I can take the telling measurements. What do you think?

Yes there is a heavy wire between them.
Lets work from a photo and my copy of the shop manual. if you post some photos of your car's harness etc then that will be better of course.

 

[Tool.Man]

Let's see if I can beat you posting. My manual is different from yours but mine seems to match the vehicle's wiring, save for color mismatches. The two manual are relatable, though. I'm not clear where the small image labeled "ammeter" is within the harness.

It's already up to 97F here and going for 106F. The car sits in the sun so I won't be outside again until 7:00 tomorrow morning.

P.S. Finding junctions 2 and 3 will be my goal.

 

[Mattax]

Here's a clear photo of standard '76 from a car that was being sold on-line.
Arrows point to the fusible link junctions. Dark Blue with gray fusible link in this case is J1 (feed to the key switch).

The fat junction is one end of the shunt?

Here's the FSM standard option (the 65 amp option removed for clarity)

Now according to this drawing , the R16 junction is seperate from the junction with the fusible links.
Does that match what you see on your car?
Sometimes shop manual drawing were done before manufacturing engineering had the final production version worked out.

it also shows CE1 which is the bulkhead multiconnector. I might have that page.

 

[Mattax]

Yes match the what you have on the car to the manuals. The car is real!
There is the differnces in ma uals and also in the way hte car may have been optioned.
I've been focused on the standard option wiring.

The other ends of A11 and R16 will be in multiconnector cavities 29 and 12.

 

[Mattax]

You could disconnect the battery and check for continuity/resistance between the battery terminal connector and the alternator output ring terminal
Carefully remove the bulkhead connectors and check for continuity between the terminals that the R16 and A11 wires go to.

 

[Bugman]

bulletin

 

[Bugman]

printed circuit

 

[townsend]

The round cluster connector shown in post 19 has 11 cavities which is the same as earlier models. The difference is the 1975 and older connector uses 9 cavities leaving two empty. The 1976 model uses all 11. The additional spots are marked with a X in post 19. So the 76 model has traces on the circuit board to feed the ammeter.

 

[Mattax]

I'm not clear where the small image labeled "ammeter" is within the harness.

The FSM scan I'm working with shows this

CI 10 is the connector to the circuit board Bugman shows in post #19

 

[townsend]

A comment about the 1976 Chrysler service manual.
In 76 the manual came as a 2 volume set.
The chassis body service manual and the electrical service manual which includes the wiring diagrams.
There must not be much demand for the electrical service manual. There are some electrical service manuals on eBay selling for less than 20.00 including shipping.

 

[Tool.Man]

I have both manuals

 

[townsend]

Since you have the manuals, would you see if the diagram in post 11 appears in the electrical service manual. Thanks

 

[Mattax]

Yes. Good question.

As far as continuity and shunt measurements.
Cluster is on the bench, harnesses in the car?

Check for continuity between R16 and A11 at the cluster connector.
If open or high resistance move to the bulthead connector under the dash.
Check by back probing.
if open or high resistance, remove the connectors on the engine side. Rinse repeat.

if open or high resistance, check against other wires connecting to the same junction.
narrow down the location before resorting to unravelling harness tape or poking holes in rubber seals.