ignition/key switch question

[daytona kid]

I bought a new ign/key switch for my 68 charger and it has an extra male connector blade. It is the one marked grd and my stock harness connector plug has a slot for it but no grd wire. Do I need to add a ground wire to that male grd blade? I did installed the new switch already and it seems to work ok without it grounded with a wire.

 

[Nacho-RT74]

Leave it like that.

 

[MoparLeo]

You can never over ground an electrical part. Number one cause of intermittent problems are grounds.

 

[F4R/T]

I’d double check the FSM if it’s supposed to be used use it, also take a test light and verify no power on that lug.. just in case it’s marked wrong .

 

[Nacho-RT74]

You can never over ground an electrical part. Number one cause of intermittent problems are grounds.

Ignition switches don't need ground, EXCEPT if they actually send ground at some stage, which in this case is not. Some mid to lates 70s Mopars do as far I recall.

Would be nice to check if the switch actually RECEIVES ground or the tab is really to SEND ground being taken throught the chassis

 

[daytona kid]

It seems I now have a problem with a bad connection at the key switch. I'm going to see if the big connector on the harness has some corrosion or a broken or loose wire. What is happening is it appears that my coil is not getting voltage during cranking, it fires up as soon as I let off the key. That's telling me there's something going on at the switch. Anyone ever heard of this situation?

 

[Don Frelier]

Yes usually the bulkhead connector

 

[Nacho-RT74]

Are you loosing the brake light on cluster while cranking?

 

[daytona kid]

Are you loosing the brake light on cluster while cranking?

I don't have that hooked up, I think I lost the oil press gauge, and turn signals. I could wiggle the harness near the key switch and it would remedy those. But the cranking problem is on going. I need to check volts at the coil while cranking, I bet it's 0, till I let off the key.

 

[Nacho-RT74]

It points out on a bulkhead issue if not the ign switch, assuming wires are good an not broken. You are loosing the Ign2 power ( brown wire ) while cranking.

The brake light is a good sign to confirm this, since the brake light gets the power from Ign1 ( run circuit blue wire ), but while cranking the ign switch doesn't directly feed this circuit, it gets a feed back from Ign2 circuit throught the ballast.

Ballast is good since you're getting started up the engine and this just posible with a good ballast via Ign1 circuit, so it points out on a failure on Ign2 circuit

 

[RJRENTON]

Ignition switches don't need ground, EXCEPT if they actually send ground at some stage, which in this case is not. Some mid to lates 70s Mopars do as far I recall.

Would be nice to check if the switch actually RECEIVES ground or the tab is really to SEND ground being taken throught the chassis

IF "if they (presumably the ignition switch) actually send ground at some stage".....what does this mean? Do not speculate on something you do not understand or unsubstantiated. "Some mid to lates 70s Mopars do as far I recall"..... to which SPECIFIC model or models were you were referring to? Inquiring minds want to know....
BOB RENTON

 

[Nacho-RT74]

1st... it seems the judge motion to my posts will never stop... whatever.

2nd.. it seems some late 70s Chrysler needed this signal for whatever reason. I can't recall who told me that at Moparts and in fact told me some sensors/relays required this to be activated while cranking. I don't have or need to judge that because if wasn't true there wasn't a reason to make a replacement ign switches with a ground provision wire on post 70 ign switches.

I know as a fact mid 70s Mopars got a relay to deactivate the voltage regulator while cranking to save from the voltage decay while the cranking moment... but this specific function wasn't made by a ground trigger as far I recall.

Now WHY on a pre 69?... hell I don't now.. why not test it? I don't have one of those switches in hands ( even less in Spain right now... maybe being in Vzla I could )

Why don't you make by your self the test to check is this tab sends chassis ground while in RUN or cranking? Once again I'm not taking conclusions, just thinking out loud on what could be the reason for that ground tab, where an ignition switch doesn't NEED a ground signal to switch on or off the car electrical system.

Make it by yourself and post the result of the test... and we learn all together about this tab function.

Done here.

 

[70chall440]

IMO you cannot over ground the vehicle, when new the cars obviously worked fine but now 50 years later, the wiring is not what it was and adding grounds can and do help. Put another way, grounds are not harmful and you have nothing to lose by adding them. Why this switch has a grd tab is beyond me but I would probably grd it, it just might help that switch live longer.

 

[Nacho-RT74]

Ign switch DOESN'T NEED GROUND TO WORK!!! is just a mechanical part what routes power from one side to the other, or simply cut it. If was an electric or magnetical piece it would but is not. The ign switch is just like the wall switch to turn on your bedroom roof light. Your light needs ground, but not your switch.

 

[RJRENTON]

Ign switch DOESN'T NEED GROUND TO WORK!!! is just a mechanical part what routes power from one side to the other, or simply cut it. If was an electric or magnetical piece it would but is not. The ign switch is just like the wall switch to turn on your bedroom roof light. Your light needs ground, but not your switch.

View attachment 1007843

Once again, an erroneous conclusion. Are you sure the ground tab on the subject switch is NOT for the key buzzer contact or perhaps for a vehicle alarm contact. Only a complete disassembly of the switch will verify it's use. Or a thorough study of the specific vehicle's FSM wiring diagrams. BTW...the little science demonstration looks nice but serves no useful purpose other than to confuse the audience, as it has nothing to do with subject at hand. In addition, because a "home light switch" is grounded by code requirements, separately and thru its enclosure, to prevent an electrocution of the user, should any current carrying parts become damaged or wet.
BOB RENTON

 

[daytona kid]

Guys I appreciate your enthusiasm but now my main problem is that my motor doesn't appear to be getting any fire during the cranking position of the old or new switch, then right as I let off the key it fires up.. I checked the connectors and cleaned the female spade connectors in the old harness. For the past year the car was cranking at the first touch of the key, now it just spins. It does finally crank but kinda tricky and takes about 3 tries. I gotta rig up my voltmeter on my coil where I can see it while cranking, maybe on top of my air cleaner.

 

[daytona kid]

I checked the voltage on the coil during cranking and it was ok. It is really strange the way this problem is acting. Will not hit a lick while starter is energized no matter how long it spins, let off the key and vrooom., crazy!

 

[70chall440]

I ran into this problem once before, as I recall the solution was 2 wires had to be connected. Its not allowing full contact when cranking IMO.

 

[Glenwood]

What's the voltage at the coil while cranking? I believe IGN2 (brown) sends 12v from BATT to the coil, bypassing the BR when starting. In run position, the BR is back in the cct from IGN1 (blue), reduced voltage to the coil. When I changed to a pertronix system and removed the BR, I forgot to connect the brown and blue together, which acted similar to what you are describing. Don't worry about the GND tab. Some of the accessorized Chryslers, ets, had a ground wire connected to it. If your harness didn't have a wire for it, it should not be an issue.

 

[Nacho-RT74]

Or a thorough study of the specific vehicle's FSM wiring diagrams.

already have made it, MANY times THANK YOU. That's why I said.

just enjoy keep judging my posts with just that purpouse... nice. ( and sometimes without read it correctly ).

I checked the voltage on the coil during cranking and it was ok. It is really strange the way this problem is acting. Will not hit a lick while starter is energized no matter how long it spins, let off the key and vrooom., crazy!

while cranking even the power to coil is being bypassed by the Ign2 circuit straight from ign switch ( brown wire ), when releasing the key, it should jump out inmediatly to the Ign 1 ( blue wire ) throught the ballast circuit without a "time gap" because will miss the spark keep the engine running after the initial start up impulse.

when we got ECU, this is even more important, because while cranking the ECU gets sourced also from Ign1 THROUGHT the ballast, then releasing the key is when ECU gets full power.

Now, everything points out to an intermitent failed conections. If we trust on the new ign switch being really a good piece, this just points out to a broken wire or incorrect conection into the Ign1 circuit. It uses to be quite common a missed contact into the bulkhead.

The brake ( and oil when present ) light on cluster it uses to be a good testing procedure for this power continuity into the Ign1 and 2 circuits being on the cab while cranking and looking at it

If you had electronic ignition, some other failure comes to mind, such as failling conection at dist plug, or even ECU plug, ( trusting on good ballast and ECU ).