Allpar Forums banner

1 - 15 of 15 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hello all!

I am new to the forums but excited to learn from all of you. I bought a 73 Valiant last month that is running generally very nicely, but a few nights ago, the engine refused to turn off when I turned the key back into the off position-- you can move the key all around, take it out, no change. I've had to turn off the engine by pulling the center line on the distributor cap both times I've driven it since then. So, some questions:

1. Opinions on whether this is the ignition cylinder? the ignition switch? or both?

2. How difficult is it to switch out the ignition switch once I've got the wheel and casing off? I'll try the cylinder replacement first, but am curious. I've got a steering wheel puller and plan to dig in tomorrow morning. Any other advice?

Thank you all so much! I look forward to your answers and, hopefully, to more questions in the future as I start to fix this puppy up!

Kristin
 

·
Super Moderator
Joined
·
21,401 Posts
Welcome to Allpar. Possibly an ignition switch if it has broken internally to short the 'Run' and 'Off' positions together (rare).
I have also seen feedback issues in the steering column wiring where the battery voltage 'shorts' to the ignition voltage and keeps the ignition coil energized.
A process of diagnosis where you unplug connectors one-by-one until the engine quits would help locate the cause. I have also seen accessories or added wiring to a tape player or CB radio cause a battery power feedback to the ignition circuit. Like an unintentional 'hotwire'.
 

·
Registered
Joined
·
4,694 Posts
. . . . Possibly an ignition switch if it has broken internally to short the 'Run' and 'Off' positions together (rare).
I have also seen feedback issues in the steering column wiring where the battery voltage 'shorts' to the ignition voltage and keeps the ignition coil energized. . . . ..
To add to the tip I C presented follow this link and scroll to the wiring diagram for 1973 model year, Valiant A and Valiant B diagram.

Mopar Wiring Diagrams - MyMopar.com - Dodge Plymouth Wiring Diagrams (at http://www.mymopar.com/72to76_wiring.htm )

Look at the attached image. It is an enlargement snippet showing the bulkhead connector at the firewall that carries electrical power to and from the ignition switch. It is possible that the connector terminals are shorting electrically together and providing constant power to the ignition system.

Valiant Dart 1973 Ignition at Firewall 33.gif
 

·
Super Moderator
Joined
·
32,052 Posts
Hello all!

I am new to the forums but excited to learn from all of you. I bought a 73 Valiant last month that is running generally very nicely, but a few nights ago, the engine refused to turn off when I turned the key back into the off position-- you can move the key all around, take it out, no change. I've had to turn off the engine by pulling the center line on the distributor cap both times I've driven it since then. So, some questions:

1. Opinions on whether this is the ignition cylinder? the ignition switch? or both?

2. How difficult is it to switch out the ignition switch once I've got the wheel and casing off? I'll try the cylinder replacement first, but am curious. I've got a steering wheel puller and plan to dig in tomorrow morning. Any other advice?

Thank you all so much! I look forward to your answers and, hopefully, to more questions in the future as I start to fix this puppy up!

Kristin
Good suggestions above.
DO NOT shut the car off by pulling the center coil wire. This carries 20,000 to 30,000 volts and can give you a SEVERE shock. Ask me how I know. :(
 

·
Super Moderator
Joined
·
37,275 Posts
I had a car where an electric cooling fan was improperly wired. At times, the car refused to shut off. Once I fixed the fan wiring, it never happened again.

No idea how stock or modified your car is though.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #6
Thank you all so much! Questions:

1. In order to unplug the connectors one by one-- where? At the large junction under the hood? or somewhere under the dash/steering?

2. While I am working on learning to read wiring diagrams/diagnosing the problem, is there another safer way to turn off the engine?

Thank you for bearing with me-- I'm just beginning!

Kristin
 

·
Got parts?
Joined
·
2,610 Posts
You might disconnect the negative ground cable at the battery to turn the car off. It will take a bit longer than the coil wire, and be very careful not to touch the positive post, or any metal part of the car, with your wrench. The nut should be 1/2", but you might check that before starting the car. This might be a good time to clean any corrosion from the posts and terminals.

This will involve a bit of work, but you could install a shut-off switch in the wire leading to your ignition switch.
 

·
Virginia Gentleman
Joined
·
14,810 Posts
Well, if it was a manual transmission, I would stick it in gear and dump the clutch. That's what I had to do when the ignition cylinder jammed in the run position in the '79 Monza I once owned. Then I had to disconnect the battery so as to not drain the battery. Drove it that way for about a week until I could get to a local Chevy dealer - I was stationed at Fort Sam Houston for training at the time.
 

·
Super Moderator
Joined
·
32,052 Posts
You might disconnect the negative ground cable at the battery to turn the car off. It will take a bit longer than the coil wire, and be very careful not to touch the positive post, or any metal part of the car, with your wrench. The nut should be 1/2", but you might check that before starting the car. This might be a good time to clean any corrosion from the posts and terminals.

This will involve a bit of work, but you could install a shut-off switch in the wire leading to your ignition switch.
It will stay running if the negative cable is pulled. Chrysler did that in 1960 to prove that an alternator vs a generator could keep a car running without the battery.
You could remove the air cleaner lid and cover the carb throat with a rag to stall it out (making sure it doesn't get sucked in). Or better still, unplug the ballast resistor so that power to the primary coil winding is cut off.

Problem is, you don't want to leave the ignition on for an extended time with engine off, so after stalling it, disconnect the negative battery cable.
 
  • Like
Reactions: AllanC

·
Registered
Joined
·
4,694 Posts
. . . Chrysler did that in 1960 to prove that an alternator vs a generator could keep a car running without the battery. . . . .
Chrysler made a commercial for the 1961 model year when alternators were installed on all vehicles. Two 1961 Plymouth Fury models were started and batteries removed. The cars traveled from Detroit to Chicago and included a 1 hour lunch stop with engines left idling. It was conducted in the winter time so minimal electrical load on the vehicle. That was the era when Chrysler was first to adopt new technology and advertise accordingly. GM did not adopt alternators on all its corporate vehicles until 1963 and Ford Motor Co moved to alternators in the 1964 and 1965 model years.

Another reason that disconnecting a battery cable while the engine running is NOT good practice is that can create a voltage spike. Year 1973 was the time when Chrysler adopted electronic triggering on the primary ignition circuit. This replaced breaker points in the distributor. A voltage spike might harm the electronic ignition distributor control module?
 

·
Registered
Joined
·
1,810 Posts
If it's a tilt column th first thing I'd do is cycle it up and down it's full range. If that didn't do it try the steering wheel left to right.
As for shutting it down I would think plucking the wire from the ballast resistor safer and effective?
 
  • Like
Reactions: Bob Lincoln

·
Premium Member
Joined
·
20,101 Posts
I would start with the ignition switch by unplugging the wire connector to the cylinder, make sure wires haven't melted and are connecting there first. I have had my ignition switch do this. If everything looks good, no melted or shorts there, then yeah, start looking at other wires to make sure something hasn't melted to another wire to give power to the ignition when the key is off. If you have another ignition switch/cylinder you can plug into the harness to test the ignition switch itself, that would speed up the troubleshooting.
 

·
Super Moderator
Joined
·
21,401 Posts
I have seen the plastic bulkhead connectors on the firewall melt from the heat of a high current-poor connection and terminals touch together because of this.
You may see signs of heat at the connector. Some connectors were so badly melted, that I could not pull them apart.
 

·
Registered
Joined
·
207 Posts
A 73 Valiant should have the connector to the ignition switch near the bottom of the column under the dash. It may have melted the connector and the wires may be touching. It has happened to me before.
 
1 - 15 of 15 Posts
Top