Sudden death

[ascari]

I was happily cruising in the -66 New Yorker yesterday, when out of the blue the engine died. Tried to restart, won't crank, no lights on dash, no relays clicking. It turns out everything electrical is absolutely dead - except the horn.

Battery appears to be fully charged, at least it reads 14.4V and jumping made no difference. But like I said, the horn works great! Always something.

Does anyone have a suggestion what might be the cause? Has anybody else experienced this type of failure, and if so what was the cause? And how/where do I begin troubleshooting this issue?

 

[GOLDMYN]

check the hot wire to the coil?

 

[Devinism]

The underhood fuseable link. Common failure back in the day.

 

[ascari]

Thank you so much for the responses!

Question: If it turns out to be a blown fusible link, is there a particular amp/gauge/etc. I should shop for, or are they one size fits all for all Mopars?

 

[Ross Wooldridge]

12 AWG fusible link for your car. Fusible link will be found on the firewall, coming out of the bulkhead and going to the stud on the starter relay. You can make your own for cheap, just go to Napa and buy the raw fusible link wire - comes in a roll.

 

[1966newport]

and you need to determine why it failed

 

[CBODY67]

I had a somewhat similar, but not exactly similar, situation one evening years ago with the '67 CE23. I had not driven it much and went a few blocks to the gas station. I decided to take a few extra blocks' distance back to the house. I turned the corner off of the main street and the engine stopped. I had lights, but no starter. We pulled it back to the house and parked it at the curb. I went out the next day, after looking at the FSM wiring schematic. I ended up with the "big red wire" going into and out of the wiring bulkhead connector. Tracing it inside, all was well until I found a charred section on the input side of the ignition switch, several inches before the switch. Under the chewing gum "silver" wrapping paper was a section of bare wire which had corroded. Obviously, the prior owner had patched into the wire at that location, just stripping away the insulation and twisting another wire around it. Then later covering it with the chewing gum paper for insulation. When I found that, I turned the key on and that section of the wire got warm.

Next day at work, I got two solderless terminal sets (with insulation outer protectors) and a section of 10ga red wire. When I got home later, I commenced cutting out the damaged section of wire and assembling my good patch wire into the circuit. When done, everything worked as designed.

In later years, I had another "no start" situation. I traced it to the same red wire where it attached to the inner side of the bulkhead connector. The wire's terminal was a bit loose on the connector, so it was easy to reattach.

Luckily, I had a volt-ohm tester which I could use to check continuity in the circuits. Something like that can be of assistance to you, too, in this case. First thing is to read the FSM's excellent wiring schematic to determine the feed circuits for what was not working when the failure happened. In my case, that big red wire was the feed circuit for the ign switch (and all circuits that feed from there, i.e., switched power). Methodical diagnosis can be your friend, in this case. For good measure, ALSO check continuity through the Ammeter gauge.

Please keep us posted on progress and findings,
CBODY67

 

[bigmoparjeff]

Sounds like you either have a bulkhead connector that's in the process of burning up, or a failed ammeter.

The horn works because in '66 the horn relay takes it's power right off of the starter relay. Everything else goes through the ammeter.

It's time for the MAD bulkhead bypass:

Underhood Ammeter Bypass

As requested,A couple members,some experienced,some newbies,asked for me to do a detailed pictoral of adding the extra wire under the hood that will keep your car alive and save your sneakers for walking the dog. I done this soo many times I never really did any pics of it. Using Maggie's 69...

www.forcbodiesonly.com

Here's what can happen when things go really wrong with the stock wiring setup:

Jeff

 

[Big_John]

12 AWG fusible link for your car. Fusible link will be found on the firewall, coming out of the bulkhead and going to the stud on the starter relay. You can make your own for cheap, just go to Napa and buy the raw fusible link wire - comes in a roll.

WAY TOO LARGE!!!!!!!!!

First rule of fusible links is take the size of the wire and subtract 4.

The best way to find the size is to look at the FSM and get the size that Chrysler put in there. In this case, since his horn still works, the link that might be burnt out is the 16 gauge coming from the starter relay and going to the bulkhead disconnect. On page 8-79 in the FSM wiring diagram is this answer. Circuit A1B.

The horn fusible link is 20 gauge and is circuit H1 on the same page.

This is why cars burn.... You've just taken the protection out of the circuit by oversizing the fusible link.

The other issue would be "IS THIS REALLY THE PROBLEM?". Yes, it does sound like it, but without doing some checking, you don't know. It could be a lot of other issues.

 

[live4theking]

Being methodical is what is going to find the issue you're having. I agree with everything that has been said. I had this problem with my 68 NYer. If it were me this is how I would proceed.
1. Check the fusible link. If it's bad replace and figure out what drew too much current. If good step two.
2. Take the bulkhead connector apart and check for signs of excess heat on the large red wire. While you have this apart clean it and apply some De-Oxit to all contacts.
3. Follow the large red wire under the dash looking for bad spots, splices, signs of heat.
4. Check to see if the ampmeter has failed "open". You may have to pull your instrument cluster to do this.

Below is a link to the thread about when this happened to me.

No Power

My issue was the fiber washers on the back of the ampmeter shrunk with age which left the wires loose. Once I tightened them up the problem was solved. I have also done the ampmeter bypass to so now it isn't a worry.

I hope this helps.

 

[ascari]

Thanks for all the insightful replies! Very helpful! I will let you know what I find.

 

[Ross Wooldridge]

WAY TOO LARGE!!!!!!!!!

First rule of fusible links is take the size of the wire and subtract 4.

The best way to find the size is to look at the FSM and get the size that Chrysler put in there. In this case, since his horn still works, the link that might be burnt out is the 16 gauge coming from the starter relay and going to the bulkhead disconnect. On page 8-79 in the FSM wiring diagram is this answer. Circuit A1B.

The horn fusible link is 20 gauge and is circuit H1 on the same page.

This is why cars burn.... You've just taken the protection out of the circuit by oversizing the fusible link.

The other issue would be "IS THIS REALLY THE PROBLEM?". Yes, it does sound like it, but without doing some checking, you don't know. It could be a lot of other issues.

Thanks for setting me straight John - I thought I remembered the correct size by memory.

Please listen to John in terms of the size of the fusible link if that turns out to be the issue.

 

[Gerald Morris]

Big John did a signal service on this thread. I use 12 gauge fusible links, because I upgrade my main current conductors to #8 AWG. I ran my new charging wire straight from the alternator to the battery in front of the engine compartment, #8 AWG welding wire. I run the fusible link for the dash from the battery to the starting relay, which takes 6 inches, a canonical length for many fusible links. From the relay, I run more #8 wire straight into the dash through a grommet, terminating in a ring terminal which I attach both leads formerly attached to the ammeter. Thus, these two conductors are fed as parallel feeds, one to the switchable stuff controlled by the ignition switch, the other feeds the "battery" circuits on the fuse block. Both of these are #12 conductors.

I completely disconnect the 16 AWG fusible link and the 12 gauge black wire from the alternator to eliminate any funny backfeed or random short circuiting from some neglected conductor finding ground.

I'd thought about feeding right to the triple weld, but the black 12 ga wire from the ammeter goes right to it on the '68. I recall it was the RED wires in the weld in my '66, which I did feed directly, as the ammeter was GONE from it already.

Anyway, like the MAD bypass, by eliminating the ammeter, one converts a serial loop to two parallel conductors. Mine just does this a little more directly. I've never had trouble with Mathilda's wiring after the early fire from the shorted alternator stud and NO fusible links in the car! (Just got it a few weeks prior then.) I expect no trouble from MY wiring on Gertrude either, and haven't had any.

 

[cbarge]

Underhood Ammeter Bypass

 

[ascari]

Update: As it turns out a previous owner has done some very creative wiring to the car. Thus, no fusible link at the firewall. After lots of head-scratching and wire-tracing I figured out that the previous owner had replaced the fusible link with a 30 Amp inline fuse, which had completely melted itself and the fuse holder. I temporarily replaced the fuse holder and put in a 15 Amp fuse just to see if the car got power, and it did, and ran like a top. So I'm one step closer, at least I know the immediate reason for the sudden death.

That said, I'm still not sure what caused the meltdown of the inline fuse, every circuit seemed to work fine, so somehow I have to figure out which load it was that caused the failure. A similar failure in the distant past is probably why the previous owner installed that fuse. I just hate intermittent faults.

I want to get rid of the fuse work-around and install a proper fusible link. It looks like the "main wire" that feeds just about everything via the ammeter is a 12 gauge. I guess that means I should go with a 16 gauge or smaller fusible link to be on the safe side? Is that correct?

Also, since I don't have anything to compare with, what should the length of the fusible link be?

 

[Ross Wooldridge]

The issue may lie at the connection(s) at the firewall bulkhead connector, and/or the connections to the amp gauge. Both can be bypassed for safety, and the bulkhead definitely should. It's a poor design, and a fire waiting to happen. There's a reason why that fuse (which shouldn't be there) melted down, as you well know.

Look up (search) MAD ELECTRICAL and Bulkhead bypass to get the info - lots of helpful stuff.

FYI, the length of the fusible link is about 6".

Update - I can see that my suggestions are old news, and that this has been covered already.

Regardless, it should be done.

 

[ascari]

Thanks Ross,
Yes, I would like to get the car's electrical system close to original spec, with the addition of the ammeter and bulkhead fixes. They're on my to-do list.

 

[EurekaSevven]

These threads are always interesting to me, because on my own 68 Newport I've never had an issue with the ammeter or the wiring, and as far as I can tell 99% of the wiring is still factory and functions perfectly. I've let the car sit for months, come back, turn the key left to "on" and still have the dash light up for each applicable function. I feel like this happens when people start messing with wiring without understanding what each circuit is for (as it seems to be the case here).

As an aside, I wouldn't even use the FSM to troubleshoot, there's a way better book for C-Bodies floating around on e-Bay that shows each wiring circuit AND how it physically fits into the car. I bought it for $35 dollars - I would use this 100% over the abstract FSM diagrams.
1968 Chrysler Electrical Assembly Manual Wiring 300 Newport New Yorker Imperial | eBay

 

[Gerald Morris]

Update: As it turns out a previous owner has done some very creative wiring to the car. Thus, no fusible link at the firewall. After lots of head-scratching and wire-tracing I figured out that the previous owner had replaced the fusible link with a 30 Amp inline fuse, which had completely melted itself and the fuse holder. I temporarily replaced the fuse holder and put in a 15 Amp fuse just to see if the car got power, and it did, and ran like a top. So I'm one step closer, at least I know the immediate reason for the sudden death.

That said, I'm still not sure what caused the meltdown of the inline fuse, every circuit seemed to work fine, so somehow I have to figure out which load it was that caused the failure. A similar failure in the distant past is probably why the previous owner installed that fuse. I just hate intermittent faults.

I want to get rid of the fuse work-around and install a proper fusible link. It looks like the "main wire" that feeds just about everything via the ammeter is a 12 gauge. I guess that means I should go with a 16 gauge or smaller fusible link to be on the safe side? Is that correct?

Also, since I don't have anything to compare with, what should the length of the fusible link be?

IFF you're planning to run all the current pulled by your dash circuits through #12 AWG wire, as the car originally came, then yes, #16 AWG fusible link wire cut with 1/2" exposed at each end, and no more than 6" of insulated conductor between these would be the canonically correct thing to do.

I would suggest some improvement to this.

Run a heavier conductor through a rubber grommet-ed home in the firewall to BOTH of the conductors on each side of the ammeter. Terminate your conductor with a good lug of the same size, I think it was a 3/32" terminal, and use a good brass 10-24 screw, washer and nut to secure thye junction. then insulate this first in shrink wrap, friction tape, then rubber tape. Last, use 3M black electrician's tape. This will make a joint recognized by the NEC as suited for high voltage. Use the FEED end of the power conductor for the overcurrent protection of the fusible link, which should be 4 AWG sizes smaller than your power conductor. Connect this to the battery, either via direct contact or at the starter relay. (The latter is probably best here.)

You can now eliminate the feed from the alternator into the dash, as you're feeding from ONE nice, fat conductor from the battery. The alternator THEN can go directly to the battery freom its charging stud. Run a conductor the same size as you chose for your main to the dash here. You can either rout it around the path the old wiring harness was done with, or, save some conductor length, thus lowering resistance, and run it across the front, outside, below the radiator, then directly to the + terminal of the battery or starter relay. Protect THIS conductor with the same size fusible link as the other.

NOW, you will have protected both of your significant power wires with fusible link wire, reduced the length of the charging path, assuring better charging if your wiring is up to snuff, and cut that damned firestrarter (ammeter) out of your circuits. Get a voltmeter and read it off the main conductor coming in.

Congratulations! If you follow the steps given above, you will have completed the Morris Bypass. Since the MAD bypass creates a supernode from the old wires when they're connected after removing the ammeter, I just went a few extra inches, removing any parallel circuit conductors of uneven length going into the dash, and feed the primary circuits off one fat conductor, while charging the battery off a shorter, heavier wire too.

I developed this approach with my 1966 Newport after an electric fire arising from total lack of overcurrent protection, which I had inherited from the previous owner. It ran over 5 years thereafter sans trouble.

 

[ascari]

Thanks for all your thoughtful responses! Lots of interesting thoughts to mull over. Not sure what a c-body novice would do without this forum.