Joined: Wed Oct 14 2009, 07:20PM
Location: Florida
Posts: 151
I just watched/saw the videos on the ammeter bypass 101 (under important threads). I recently got my 68 Chrysler Newport and within a few weeks it completely (electrically) conched out on me one day (stop light). I had a neighbor try to figure it out and he had no luck so I took it to a repair guy I've known for years. He called me back after a day or so and said that the ammeter gauge went bad. I guess all the current goes through it and since it went bad, no current could get to any other part of the car (starter etc.) He did some sort of bypass (connected the wires without going through the gauge). The gauge doesn't work but the car has been work ing fine for at least 1000 miles now. Is there anything I should double check before I get a new gauge? The car is in really great shape and I want to do whatever is best eventually. I've seen the NOS gauges on another site for about 90 bucks. Should I even try to buy one or just leave it alone since it is working? I'm thinking about going to electronic ignition soon and want to make sure I won't have any issues in the future. Thanks ahead of time for any knowledgable advice....Merry Christmas.
Joined: Sat Sep 23 2006, 04:30AM
Location: Sharpsburg, GA
Posts: 924
I think that a bare minimum, you need to remove the firewall connectors and clean them and then have a wire installed with a fuseable link running from the altenator to the battery. This will take the load off the ammeter wire that was spliced if the firewall connector gets corroded.
Without this, your chances of having an electrical fire in the future are pretty good.
Using an ammeter was a poor design decision by Mopar-they give everyone fits sooner or later. I bypassed my ammeter (spliced the wires together) and put in an aftermarket voltage gauge.
I also added a thick 10 guage wire with a fuse link from the alternator to battery to take the load off. (see diagram)
Joined: Fri Oct 07 2005, 12:03PM
Location: Central Ky.
Posts: 1575
Here ya go, Burnt Fusible link, Corroded bulkhead connections that got hot enough to melt the plastic connector & bulkhead connections.....And the car was still running pretty good. Found this doing the inspection to fix any other things while it's here.
The old Burnt Fusible with the new replacement in front.....
Replaced the whole connector body with a good used one & will solder the red wire to the new Fusible & connector...
The connector was burnt completely in the bulkhead & bulkhead melted ( as usual ) so the new red 10 ga is soldered to the original just inside the car & simply fed through, used a small drill bit to open the hole. It'll be soldered to the Fusible & there won't be any connection there anymore.
When I get back under the dash I'll check the ammeter connections & the Black charging wire coming back out was fine. All wires in both firewall connectors are getting cleaned also.
This just what you find in these old Mopars. A lot have these problems & that's why everybody says to check the bulkheads & Amp gauges. the high current & 40 years kills a lot of them but the fixes aren't that hard.
I just got this one to do some " de chevying" under the hood & check stuff & found this so it gets fixed as well. Guy just bought the car a couple of months ago.
Joined: Thu Nov 24 2005, 07:29PM
Location: So Cal.
Posts: 1111
The short answer is, "the bypass the mechanic did is fine." Most likely he unscrewed a lead from one of the studs on the back of the ammeter and then screwed it back on to the other stud.
The longer answer is what others have said- spend a day and get to know the electrical system of your car. Armed with some wiring diagrams, it's not super difficult. Have fun learning and feel confident you'll know the system in case something else like this happens! !thumb
Knowing how the car works and what it needs has helped me get it home on more than one occasion.
Joined: Thu Feb 12 2009, 02:56AM
Location: Portland OR
Posts: 690
Just to be clear, adding a wire going from the alternator output stud to the batery or starter relay, "WILL NOT" take the electrical "LOAD" off of the bulkhead connector. It will only take the baterys charging curent (which is a small amount of current) so the loads fron every other electrical component on the car will still be running through the bulkhead. What you need to do is to cut the main power wire "10 gauge RED wire" on bolth sides of the connector, under the hood and under the dash. Then connect them together with a short length of at least 10 gauge cable and preferably solder the connections and USE SHRINK TUBING to insulate and weatherproof the connections. This will take the load off the bulkhead connector. Run the cable through a rubber grommet on the firewall next to the bulkhead. Then do the same thing with the cable coming from the alt through the bulkhead. Should be either Brown or Black, Cant remember off the top of my head. Iff you do this (known as a bulkhead bypass) you will have no further issues with the main power supply feeds. Good luck.
Joined: Sat Sep 23 2006, 04:30AM
Location: Sharpsburg, GA
Posts: 924
The new wire from the alternator to the battery will allow the alternator to supply power through the bulkhead on both the black and red wires. It does help, but putting a new wire through the bulkhead connector is even better. Really you need to do both.
Joined: Thu Feb 12 2009, 02:56AM
Location: Portland OR
Posts: 690
Ah I didnt take into consireration the parralel current path. However would this not change the charging chacteristics (pardon the spelling) of the system? I do know that the length of the charge cable from the main splice to the battery is designed to drop the voltage dependant on the current or AMP DRAW! Adding a parralel path could change this value and cause overcharging? If Im correct this would cause the batterys lifespan to be considerably redused due to gassing/boiling of the water/electrolite from the cells. Whatever you do it is a good idea to periodically check the water level in the battery. Good luck.
Joined: Sat Sep 23 2006, 04:30AM
Location: Sharpsburg, GA
Posts: 924
As long as the regulator keeps the alternator voltage at 14.5 or less, it should be fine. If you look at wiring diagrams from the 70's you will notice that the factory added the wire between the alt and battery around 1973 or so, about the time they added the electronic ignition. I used the 1974 diagram to build a new wire harness for my '68 with an MP electronic distributor.
Went back and looked- they added the alt to batt wire in 71. Anyone with a c body 71 and newer has it. <span class='smallblacktext'>[ Edited Mon Dec 14 2009, 03:38AM ]</span>
Joined: Sat Dec 10 2005, 04:28PM
Location: United States
Posts: 4954
They also didn't run through the ammeter in 71. It was run on a spur circuit. Not as accurate, but it showed activity.
In 72 the wiring was greatly improved over the 71.
Here again, the bulk head connector plays a major part. Mopar used the Ammeter feed through for years. GM had an idiot light. The problem is the loads started getting heavier and manufacturing techniques got sloppier. So the load on the connections started to fail.
Those bulk head connectors can make your charging system appear to be doing very strange things
