HELP: Headlight switch triggering STARTER!!!

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theFightingFew

Always Learning/1975 Valiant Custom/1974 Valiant
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Location
Philadelphia, PA
74 Valiant - Ok this one is making me feel a bit crazy.

I pulled the instrument cluster on this car because none of the lights worked. I replaced all the bulb connectors and bulbs. Figured I'd throw in a new vr and headlight/dimmer switch while I was at it... great... hooked it up to test running an extra ground from both the back of the cluster and from the headlight/dimmer switch to ground screw inside dash.

PART I ORDERED HERE

  1. Start car - yay
  2. Pull headlight/dimmer switch - headlights lights go on NO panel lights... booooo
  3. Turn dial - no panel lights
  4. Push switch back in pull back out - STARTER KICKS ON
  5. *PANIC* Push switch back in - starter goes off (engine still running)
  6. Turn car off - turn key half way
  7. Pull switch - STARTER KICKS ON
How the heck is this even happening!!!? Some crazy bad switch?
Need some guidance... PLEASE
 
Offhand I'd say "you are crazy this cannot happen" LOLOL

First thing I'd do is try disconnecting ignition switch at the column connector and see if problem goes away

Have you done ANY other wiring repairs?

One "source of entertainment" is 74 should have the much hated "seatbelt interlock." Look for a big box under the dash with a long inline connector and pull it loos, see if that changes the problem. On a side note, the interlock has a reset box under the hood, about the size of a horn relay. RED reset button. You need to permanently splice the two yellow-ish wires together which are the "start" wire going to the start relay

Has there been any wiring malfeasance such as smoke and smell? Burned wiring? damaged harnesses?
 
I replaced all the bulb connectors and bulbs.
What connectors? Do you mean the bulb holders?

hooked it up to test running an extra ground from both the back of the cluster and from the headlight/dimmer switch to ground screw inside dash.
The first is understandable. A ground from the dimmer switch would be for what purpose?

  • Start car - yay
  • Pull headlight/dimmer switch - headlights lights go on NO panel lights... booooo
  • Turn dial - no panel lights
Not sure what access is like on your, but you can at least begin to trace the circuit from its source.
One of the fuses is for power to the headlight switch B2 terminal. If the parking lights work, then there is power flowing through that fuse.
If you don't know (because of the emergency type situation that occured), take a voltmeter set on DC volts. Place the black probe on a good known ground and the red probe on each side of the fuse. It should show battery voltage.

Power to the instrument lights comes out of the headlights switch and goes back to the fuse box. It connects to 2 amp or for '74 probably 3 amp fuse. On at least some years thats a tan wire from the switch and an orange wire out to the instument cluster. It also goes to the radio light. With the headlight switch in the first position out, there should be voltage there as well. Depending on the rheostat setting it may be less than battery IF current is flowing through it.


  • Push switch back in pull back out - STARTER KICKS ON
  • *PANIC* Push switch back in - starter goes off (engine still running)
  • Turn car off - turn key half way
Key one position rotated clockwise is RUN. (It might feel like two positions clockwise if as I recall there is a steering wheel lock.)


Pull switch - STARTER KICKS ON
How the heck is this even happening!!!? Some crazy bad switch?
The starter gets power from the battery when the starter relay closes.
So most likely somehow power is getting to the wire going between the key switch and the relay.
When the key is in the start position, current can flow from the wire into the key to the Start (usually yellow) and the Ignition Start (usually brown) wires.

As mentioned above, '74 has a seatbelt interlock that adds a layer of complexity to this, but otherwise works the same way.
Find the wire(s) connecting to the relay and see if its getting power whern the headlight switch is pulled on. If so, then why.
You should be able to do this with a multimeter set for resistance.
Disconnect the battery at the neg post. Then the positive post.
Put the headlight switch in the position that causes the starter to engage.
Place one probe on the battery feed line - the big stud on the relay or the disconnected battery terminal are easy locations to do that.
Place the other probe on the wire connector on the relay.
Early ones look like this. Not sure if '74 has additional terminal.

upload_2020-5-8_9-3-18-png.png



try an extra battery to body ground
What would this do?
 
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Early ones look like this. Not sure if '74 has additional terminal.
here's a '75 so basically your 74 should have the same layout.
Lower left terminal on an angle with the yellow wire going to it should get power only when the key is in Start.
upload_2020-10-22_14-30-13.png


Here is the scheme for the headlight switch.
upload_2020-8-2_10-1-20-png.png

Some colors may be different on your car since this is based on my '67 Barracuda.
The yellow wire from the dome light is not the same as the yellow wire to the starter relay. In the factory diagram (shop manual) each wire has a label to make that clear.
 
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Step 1-

If it didn't do it before you changed things.....undo the changes.
 
Thanks everyone I will run through all this information when I get back home... Starting with @YY1 's suggestion and provide an update!

I REALLY appreciate everyone's input and the wealth of knowledge.
 
Assuming you had to lower the steering column to get the inst' cluster out. Your ignition switch has a built on wire harness that mates to the cars harness under the column. This white plastic connector has been known to melt and could cause the cross circuits you have.
Some of the aftermarkets replacement switches have a extra small gauge black wire where the the factory placed the orange wire for column shift indicator lamp. If someone plugged this in as received/connected that orange to the black, the fuse for illumination is blown soon as the switch is turned to on or accessory.
 
HAPPY UPDATE::: (partial)
Want to start of by thanking everybody again... I only focused on the headlamp switch triggering the starter on tonight as the cluster bulbs not going on existed previously... I was able to use pretty much every one's input took a breath, broke out the multimeter and dove in...

  1. @doug 371 I had added/upgraded ground wires yesterday along with new battery terminals and battery to starter cable... which answers @67Dart273 about other wiring repairs. I had attached the new ground cables using one of those "nut rivet tools" (which is a fantastic tool IMO) with stainless steel nut/bolt so I would have a clean solid post so the first thing I did was go around and check all of that again. - NO CHANGE
  2. @Northern Grit inspected these areas and did not see anything
  3. @Mattax and @Bad Sport the new headlamp dimmer switch has a ground spade terminal on the back side which is why I grounded it there as well... and disconnected it as suggested as it was not on the original - NO CHANGE
  4. @Mattax thanks for the detailed info on testing I ran through most if not all of it and everything seemed to be doing what it should - I am going to re-read your info again because it is a fantastic step through! - BUT STILL NO LUCK
  5. @RedFish yes I lowered the column so checked everything you suggested - everything is still original on this car and I did not see anything you indicated I should keep an eye out for
THEN - while my big bologna head was shoved under the dash I saw a suspicious set of wires coming from the harness that were crimped together like they had been attached somewhere but just floating around in the air... one way black and one was gray (i think - it was getting dark I'll look better tomorrow). I inspected the back bottom of the dash and sure enough there was a ground screw/terminal that had a broken eyelet underneath it. I attached a new eyelet and attached the wires back to that spot... and NO MORE **PULL TO START** coming from the headlamp switch... :D

F'n craziness... electricmagicalnessnessness...
Now to figure out how to get the cluster bulbs to come on!!!

Tomorrow's fight.
 
Harnessed the angry pixies!!
Glad you (and they) solved it!
 
If it was a loose ground, then for some reason it had current and was back feeding through something to the starter relay.
Off hand the only thing I can think of that the headlights would feed that go to an dash panel ground would be the instrument lights and the hi beam indicator.
I'm not really familiar with the seatbelt interlock box but it does bring a bunch of wires together.
Some of the other guys know it better.
First booklet here has some info about it
MyMopar - Mopar Forums & Information - Browse MTSC by Model Year - 1974

and unfortunately keep in mind there is a possibility some wire colors on your car may be non standard :(
See the TSB here The 1970 Hamtramck Registry "1974 DODGE MODEL TSBs Index" Page
 
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I have to tell you the "fix" makes no sense---makes me wonder if there isn't an intermittent and all the shaking of wires opened the cross connect. There is no ground in the start circuit in the passenger compartment. The path for the starter relay is ignition switch-----yellow start wire-------out into the engine bay-------through the seat belt reset---------to the starter relay-----through the relay coil-------down to the transmission--------to the neutral safety switch.

That wire would have to be picking up power somehow from the headlight switch..........which has no obvious connection
 
@67Dart273 I agree 100% with you that it makes no sense. The whole episode really threw me off. I mean, I consider myself very green working on these cars but the problem itself just didn't make any sense to me AT ALL. I keep going outside and testing it... It keeps working "correctly" now but I don't trust it. I'm going to investigate further.
 
Wanted to add... To me, in my brain, it was like pressing start on the microwave and having my toilet flush... :)
 
Backfeed. Ground issue. Body to block im guessing.
 
LOL used to joke about stuff like that. I'm sure you know of the comic foxworthy and "you might be a rednick if." I used to think up nonsense about "running way too much power" (on ham radio.) Stuff like, "If you key up your handheld radio, and the antenna glows red, you could be running way too much power

One night Kevin in Spokane came on and I said "Kev how power you running?"

"Why am I loud?"

I said "the water level in the toilet is going up and down."
 
Backfeed. Ground issue. Body to block im guessing.

I don't see it. The neutral switch grounds to the block (trans) that is the ground return for the start relay.

EDIT --reread this. Backfeed yes, ground issue no, "crossed wires" in the harness somewhere
 
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You have contacts/switches in your seat bases, wiring from them under the carpet (where you were laying in the floor), a added lamp in a different type socket in the inst' panel for seat belt warning, and the interlock switch outside the firewall. Who knows how may different ways there can be a crossed circuit and/or backfeed in all this. Good luck with it.
 
Stuff like, "If you key up your handheld radio, and the antenna glows red, you could be running way too much power
When I lived on a small lot in Maine, I was experimenting with indoor antennas (magnetic loops). Circulating currents and voltages are extremely high in this type of antenna. The tuning capacitor was (partially) a short stub of RG-58 coax. Worked fine barefoot (100W) but when I keyed up the linear (500W) it set the stub on fire. Flames, bits of burned polyethylene floating in the air... My wife was impressed :eek:

Also on the subject of odd circuit paths, the A-body had a neat one. Turn on the radio, wipers, turn signal and put your foot on the brake. The radio would turn on & off with the flasher... wipers start and stop too!
 
^^I've heard of that "trick."

Yeh, those small transmitting loops are a whole different deal. I vaguely remember the first one I saw way back in old QST? CQ? magazines and back then had no imagination for the types of circulating currents that exist on those things. That is why, of course, the MFJ one uses a form of butterfly cap--because no shaft contact brush could ever handle the RF current
 
UPDATE: well the headlight switch is still working correctly - no triggering the starter...
BUT I'm still not getting instrument cluster lights... prob gonna start another thread AFTER I read everyone elses... it's really frustrating chasing this down!
 
Do ANY dash dimmer controlled lamps work? Radio, shifter quadrant, etc?

The inst. lamps circuit, that is the dimmer control gets power from the tail/ park section of the light switch, so the tail fuse/ circuit must be working first

Wiggle the 'eck out of the dash dimmer control it might be dirty. Turn on the park llights, twist the dimmer to left. (bright). Now move to the fuse panel and look for the INST fuse which is on one end of the fuse panel. That fuse should now be "hot" on both ends. The dimmer control output feeds INTO that fuse, and then from the fuse to all dimmer controlled lamps on orange wiring
 
@67Dart273 all park/headlamps, dome light, oil light, heater light (no radio) come on.
Replaced fuses for the heck of it.
Fuses hot at both ends.
Tan wire hot at switch.
Orange wire hot at canon plug.
No gear select light.
No turn signal lights but hazard flasher works.
 
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