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Weird Ignition Problem

vegiguy

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8:18 PM
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Newton, Kansas
Everything that I had gotten done on my '73 RR project was working fine, then yesterday when I went to see if the original radio that I had just put back in worked nothing happened when I turned to the key on. I tried to start it and it wouldn't even start. I checked the voltage and I have about 12 volts everywhere there should be 12 volts - including the ignition switch power wire and fuse box - when the key is turned off, but then when I turn the key to the ON position (not start) everything goes dead, even the large terminal on the starter relay. The battery is less than a year old as is the wiring on this car. The ignition switch I replaced several years ago with a NORS one I got off of eBay since I've had trouble in the past with new ignition switches that are invariably made in developing countries like Mexico or China (not that I have anything against these countries). I put the charger on the battery last night in case it needed it and that didn't help.

I'm thinking the ignition switch went bad, but I'm still baffled by why literally everything except the battery went dead when it is turned on since the switch is only one of several things that that receives a power wire from the main under-dash wire splice; you'd think the rest of the power wires would still have power. In my many years of working on cars I have never seen anything like this. Can any one think of something else that could be causing this before I go to the trouble of replacing the ignition switch?

Thanks for any ideas.
 
Off the top,, bad battery(I know-1yr). Bad ground, bad batt.cable. Just start from batt. and work your way back, connection to connection.
 
I think I'll take the battery somewhere to get tested even though I'm showing 12 volts across it's terminals. I don't think it could be the battery cables as they are new, too.
 
12v? Think you have a shorted cell in there.
 
12v? Think you have a shorted cell in there.
I used an analog multimeter because my digital multimeter quit working, so that 12 volts I mentioned is not an exact reading. I believe car batteries actually put out a little more than that.

The battery in the Road Runner is a Mopar battery, and I must have gotten it last winter because it was before covid hit us. I had another Mopar battery go bad in it so it wouldn't surprise me if it is the battery again since Mopar batteries might not be that good. I have had good luck with Delco and Interstate batteries years ago but in recent years I've even had Delco batteries fail, as they apparently aren't nearly as good as they used to be. I have had Delco batteries that lasted over ten years, but that was several decades ago.

Right now on my '78 Firebird I have a Wal-Mart battery in it because at the time I got it they were a Consumer Reports "best buy": except for at the very beginning when it mysteriously discharged and I had to take it back to the store it is hanging in their. I've also read that Duralast Gold batteries are good, but they are very expensive. I really like the idea of having a Mopar battery in a classic Mopar, but I suppose if they don't last then what's the use.
 
I really like the idea of having a Mopar battery in a classic Mopar, but I suppose if they don't last then what's the use.
You can always replace the battery in the repro case @dadsbee

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This should tell you something.

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Three things that come to mind for me. One is a battery that does not have either enough of a charge or one that cannot handle any load placed on it.
Two....The wires to the ammeter are not tight.
Three...The connections at the bulkhead came loose.
I'd have the battery LOAD tested or just slip in a known good battery and see if the problem goes away.

A little bit of info that may or may not help:
The + power for the interior comes in through the bulkhead and goes to the ammeter. The other side of the ammeter has a + wire that branches out to three places....The light switch, ignition switch and fuse block. This means that the headlight switch and ignition switch have power all the time along with the fuse box. Since you state that the power dies off when you turn the key to ON, maybe you can instead test the post on the starter relay with the ignition OFF and the headlights ON. If you get the same result, the ignition switch isn't the problem, the problem lies in the wiring.
BE SURE to respond and update this thread once you solve the problem. The results may help others here.
 
Not sure if I got this right but, if the large terminal on the starter relay is dead, bad battery cable/connection or battery or loose connection at the starter. Otherwise ???
 
the large terminal on the starter relay is dead, bad battery cable/connection or battery
I believe on my 1970 factory wiring that the hot cable to the starter comes straight from the battery. It certainly could be a non-factory way it's wired though, but that's how mine is.
I'm showing 12 volts across it's terminals.
The only real way to test any battery is a LOAD test. A near dead battery, so dead that it won't do whatever job it is intended for, can and will still show rated voltage. It's when that voltage is combined with "motion" or "work" or "flow" aka current aka amperage that it will have a big drop.
Voltage is potential energy. When it is actually in use is when it can be gauged properly.
 
My car has the "60 amp alternator" wiring in it listed in the factory service manual that splits the wiring coming off of the (60 amp) alternator in two : one branch goes thru the bulkhead connector to power the underdash splice, and the other branch goes directly thru the firewall to the ammeter and back out to bypass the bulkhead connector; all the wires have fusible links at various locations. Chrysler apparently realized that their plastic bulkhead connectors with their puny 1/4" terminals had limitations in power handling.

Mark at MAD Electrical has his own version of wiring the Mopar ignition circuit that is famous in the Mopar community, but it involves bypassing the ammeter altogether and drilling out the terminal space in the bulkhead connector then running the dash splice power-up wire straight thru from the main terminal on the starter relay, which is then also used as a junction for the alternator wire and the battery charging wire. He claims that having an ammeter in the dash where full alternator power could run thru was a mistake by Chrysler and that it can lead to having a hole burned in your instrument panel. I suspect that if this has ever happened it was due to the ammeter wire connections coming loose and too much resistance (and therefore heat) being allowed to build up. I talked to a local auto electric guy who does this sort of thing for a living - and whom I trust - and he didn't think the ammeter in the dash was the problem, and that he hasn't seen any burned out instrument panels from Chrysler ammeters like Mark describes.
 
Having an ammeter in the dash is like having a heating element there IF the wires get loose or come off. That was a huge engineering mistake.
 
Having an ammeter in the dash is like having a heating element there IF the wires get loose or come off. That was a huge engineering mistake.
That's why I put locktite on the threads so the nuts that hold the ring terminals on my car's ammeter wouldn't come loose.

Car companies used ammeters for many decades, but most did away from them about the same time that more plastic was being used in vehicles' dash area - the late sixties and early seventies. I went to the LKQ salvage yard last week where a lot of people just throw the parts they don't need - on the way to getting the parts they do need - on the ground and I couldn't believe how much plastic was laying around: it was everywhere out there. It's incredible how much plastic is in newer cars, but I suppose it's like that in all areas of our lives now from home widows and siding to single use shopping bags (that I avoid like the plague). I read that now that since demand for gas and oil is going down the petrochemical companies have turned there attention to pushing plastics (which are made form petrochemicals). I'd say they are doing a good job judging by all the plastic crap I saw laying around at LKQ!
 
Turns out is WAS the battery. Got it cranking again, and the original AM radio even works. Gotta love AM radio!

Thanks for the help!
 
Interesting trouble & need a sanity test ! Try leaving Ignition switch in "Off" position & measure Battery voltage Directly at the + & -- battery Terminals for 12.6 volts..If ok, simply turn Headlites On. If Battery Terminals voltage stays at 12 volts, Battery Is OK & some combination of bad wiring connection (hi resistance) needs to be traced down & corrected.....tom.
 
glad you got it. I was going to say to load test with 100 Amp or more load on the battery and cables. Multimeters have really high input impedance > 1 Meg-Ohm so they read voltage without placing any real load on the circuit. For checking basic lower current wiring like 14-18 AWG, I like using a 10-Ohm 25 or 50 Watt resistor to load the circuit. That is slightly over 1 amp current (I=E/R) through the circuit (13/10=1.3 Amp)
If checking a power wire in the car with only a multimeter, it would put a load of less then 13/1,000,000 = 0.000013 Amp, or 13uAmp.
 
glad you got it. I was going to say to load test with 100 Amp or more load on the battery and cables. Multimeters have really high input impedance > 1 Meg-Ohm so they read voltage without placing any real load on the circuit. For checking basic lower current wiring like 14-18 AWG, I like using a 10-Ohm 25 or 50 Watt resistor to load the circuit. That is slightly over 1 amp current (I=E/R) through the circuit (13/10=1.3 Amp)
If checking a power wire in the car with only a multimeter, it would put a load of less then 13/1,000,000 = 0.000013 Amp, or 13uAmp.
Good description of the problem w/an unloaded voltage measurement.
 
I did the "MAD Mod" with #6 wire from the alternator to the starter relay, and from there to the battery. Put an extra fusible link in each #10 lead going in to the firewall bulkhead connector, and disconnected the alternator gauge altogether. I will eventually have the gauge converted into a volt meter.

Why? Because when I got the car there was a burned-out ammeter gauge in the trunk, and when I replaced the wiring harness in the dash, the #10 red and black wires in the harness had melted their insulation into the wires adjacent to them, the cause of many electrical gremlins.

Reason #3 is I have been to countless junkyards, and 8 out of 10 old Mopars with "Alternator" gauges (A, B, C, and E- bodies, never any Imperials for some reason [they're rare as hen's teeth to start with], but especially the trucks and vans into the early 80's) show subtle signs of problems with or near the alternator gauge. Bubbled gauge faces, melted needles, bypassed gauges, obvious quick fixes by owners or car stereo installers (terminals in the bulkhead connector drilled out and replaced with a new wire through the hole, new wiring poking through the firewall, melted plastic in the dashboard near the wiring harness, etc.).

Monkeying with the accessory load seems to be the #1 commonality. Puttin' "Bump in the Trunk", mood lighting, disco balls (found one in a cargo van conversion, complete with wall to wall shag carpet and a stained mattress - don't worry, I got checked for STD's after that find), fog lamps, CB radios with illegal linear amplifiers, DVD systems for the kids, electric fuel pumps, etc. --They mess with the balance of things. Chrysler engineered the electrical system adequately for the design, but without a crystal ball for 50+ years of future technological innovations combined with 50+ years of weather cycles and their effects on wiring deterioration.

Mopar, and even Delco-Remy and Motorcraft did a heck of a better job with electrics than those Lucas boys across the pond [all you classic British car owners, from Morris to MG to Rolls-Royce and everything inbetween say amen?]. Hail Lucas, the prince of darkness...

While admittedly automotive electrical is not my forté, I am an electrical apprenticeship master instructor with 16 years of installation experience and 7 years of classroom experience, mostly centered around low voltage communications systems. I'm intentionally keeping electric jargon out of this post to make it accessible.

Even though my plan is to retain a stock appearance as much as possible, I have yet to find anyone (except for the folks that whine "KEEEP IT AWLLLL ORIGINALLLL") that has given me a compelling argument against my decision.
 
Mopar, and even Delco-Remy and Motorcraft did a heck of a better job with electrics than those Lucas boys across the pond [all you classic British car owners, from Morris to MG to Rolls-Royce and everything inbetween say amen?]. Hail Lucas, the prince of darkness...

I hear you on the Lucas. Planning the re-wire of my '73 Jensen Interceptor. I want to keep the Lucas switches for the stock look, but they will just be activating relays to take the loads off the switches.
For the lower current interior circuits, I found these Arduino type relay modules are really nice. Link is for an 8 relay module, but they have 2 & 4 relay modules also. Relays are 10Amp rated. Each relay can be triggered with either high or low signal, configured with jumper on the board. Only issue is mounting / enclosure for the module. Going to try the enclosure below with the relay card.

https://www.amazon.com/gp/product/B00LW2GA5Y/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

https://www.amazon.com/Hammond-Manufacturing-1591DSFLBK-STYRENE-FLANGED/dp/B005T8OEGO
 
Oooh... Daddy like! I might try that enclosure for a project as well. Wish they listed the actual dimensions of the box...
 
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