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68 RR Ignition Switch

Ed Martin

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I think I will have to replace my ignition switch to see if I can get more than 9.4 volts at the + coil while cranking (key in start). Other posts indicate the switch could be the problem. I have already replaced the coil, resistor and ECU. Battery is at about 12.4 volts. I'm sure the resistor is hooked up right because in "run" I get about the correct 7.4 volts at + coil. Do I need to replace the lock cylinder at the same time or is it possible to use the old cylinder? If I can use the old cylinder, is there some trick to matching it with the new switch? Also, did 68 RRs have the switch light? I don't remember ever seeing one, but there is a hole in the dash where it would be. Thanks for any help!
 
The lock cylinder should transfer fine. Roadrunners were strippers. Higher trim level models would use extra lamps.
Mike
 
The lock cylinder should transfer fine. Roadrunners were strippers. Higher trim level models would use extra lamps.
Mike
Great, thanks so much Mike!
 
If the engine cranks, then I'd think the ignition switch is good. Your problem MIGHT be at the bulkhead connector. Check the ballast resistor bypass wire at the bulkhead, If it is the same as the '69, it should be a brown wire.
 
If the engine cranks, then I'd think the ignition switch is good. Your problem MIGHT be at the bulkhead connector. Check the ballast resistor bypass wire at the bulkhead, If it is the same as the '69, it should be a brown wire.
Thanks. I will take a look. Is that the wire coming directly from the ignition switch start terminal?
 
It runs from the switch (IGN 1) terminal to the bulkhead connector (in the cabin, under the dash), and then from the bulkhead connector (On the firewall) to the ballast resistor. My guess is that your problem might be the spade connector contact on the firewall side. Just backtrack and follow the wire from the ballast resistor to the bulkhead connector. I can give you the exact location if needed. I suspect your '68 is the same as my '69.

Other than voltage, what symptoms are you having? Does it crank, but not start until you release the key?
 
It runs from the switch (IGN 1) terminal to the bulkhead connector (in the cabin, under the dash), and then from the bulkhead connector (On the firewall) to the ballast resistor. My guess is that your problem might be the spade connector contact on the firewall side. Just backtrack and follow the wire from the ballast resistor to the bulkhead connector. I can give you the exact location if needed. I suspect your '68 is the same as my '69.

Other than voltage, what symptoms are you having? Does it crank, but not start until you release the key?

I've got the location of that wire at the firewall (I have the original factory manual with wiring diagrams). The other day I had measured the resistance from that terminal to the resistor and there was none, but need to look at the connector itself (as you say). Do those connectors just get corroded and cause resistance or what, or they sometimes need replacing or cleaned up?

It cranks good, but will not fire at all. And I assume that's because the voltage at coil is only 9.4 when cranking when it (I think) should be close to battery voltage of 12.4. When I release the key nothing happens. I need to check some more along that circuit.

I appreciate your good help.
 
All those bulkhead connectors can get oxidized over the years. I got lucky. When I bought my car it was 47 yrs old and all the bulkhead connectors where clean, so I just used some Di-Electric grease to keep them that way, but I have seen pictures of some that where in terrible condition.

It cranks good, but will not fire at all. And I assume that's because the voltage at coil is only 9.4 when cranking when it (I think) should be close to battery voltage of 12.4.
Correct, that is the purpose of then brown resistor bypass wire, to provide full battery voltage to the coil during cranking for quicker starts. In my case, it would only start when I released the key. After several checks, I finally though, just maybe those tow spade connector just might not be making contact, so I used a small screwdriver to very slightly bend the contacts and voila, she fires on the first crank.

When I release the key nothing happens.
THAT throws a monkey wrench into my thinking, but I'd still concentrate on that bypass wire first.
Maybe run a redundant wire with alligator clips from a hot wire directly to the coil and see if that works. If so, you know the problem is in that bypass circuit for sure.
 
All those bulkhead connectors can get oxidized over the years. I got lucky. When I bought my car it was 47 yrs old and all the bulkhead connectors where clean, so I just used some Di-Electric grease to keep them that way, but I have seen pictures of some that where in terrible condition.


Correct, that is the purpose of then brown resistor bypass wire, to provide full battery voltage to the coil during cranking for quicker starts. In my case, it would only start when I released the key. After several checks, I finally though, just maybe those tow spade connector just might not be making contact, so I used a small screwdriver to very slightly bend the contacts and voila, she fires on the first crank.


THAT throws a monkey wrench into my thinking, but I'd still concentrate on that bypass wire first.
Maybe run a redundant wire with alligator clips from a hot wire directly to the coil and see if that works. If so, you know the problem is in that bypass circuit for sure.
 
Hello Ranger 16. I am still working on getting my RR to start. I replaced my ignition switch and that might have helped (my old one had some resistance between the battery input and the start terminals at the switch). I now still only get 9.6 V at the coil in start (even thought it does crank the starter). Now I want to look at the brown start wire that goes to the resistor (bypass) to the coil at the bulkhead.

Here is a picture of my bulkhead connections. Is this like your 69? Do you just pry the three individual connectors (each with 8 wires going in) off at the nubs where it attaches to the main connector? And can just the middle one be pulled off to try to get at the spade connector to check for oxidation/corrosion or whatever?

bulkhead wiring connection 025.jpg
 
Each one of those three connectors can be individually removed. Look closely and you'll see a locking tab on each side that needs to be released to pull the connector.

The locking tabs show up pretty good in this picture. A long thin bladed screwdriver works well in the little slot you see at the base of the tab to gently pry it back just enough to release the tab and pull the connector.
NOS-MoPar-Bulkhead-Connector-1966-68-Fury-Polara-Monaco.jpg


Sounds like you are not bypassing the ballast resistor. You should be getting a full 12v while cranking and then drop back to 9.6 (or so) when running. Are you sure the ballast resistor is wired properly (not bass ackwards)?
 
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