Replacement Headlight Switch Won't Work Like Original?? Help!

[Bkndsdl]

Guys, so I bought a replacement switch for my '67 C10. Looks the same, everything looks good, but when I put it in the all the way in position, which normally turns all lights off, the parking lights are on. If I pull it out halfway, which is normally to turn the parking lights on, the front parking lights go off but the tail lights stay on. When I pull the knob all the way out, the headlights and parking lights are on. This happened on the two switches I bought from the local parts house; both did the same thing. What gives?? Can't drive my truck until I have lights, and the original is broken.

[Palf70Step]

If you can compare the pinouts of the new switch to the older broken one. Sounds like something is not pinned right or the factory wiring has an issue.


The pics and video may help with the troubleshooting.

https://www.youtube.com/watch?v=ryuwnYO9GUw

[chiefcfd]

Something else to check. Is the stem fully seated in the switch? Did you use the new stem or are you trying to use the original? It's a multi switch inside and sounds like it's out of line for some reason.

[Palf70Step]

I agree also with the above (forgot that part). 67's tend to have some things different and maybe it has an older style switch assembly/knob.

[Bkndsdl]

[quote=Palf70Step;9035999]If you can compare the pinouts of the new switch to the older broken one. Sounds like something is not pinned right or the factory wiring has an issue.

Thanks Palf, I'll take a look. Problem is, this is the second one.....two different manufacturers. both did the same thing.

Originally Posted by chiefcfd

Something else to check. Is the stem fully seated in the switch? Did you use the new stem or are you trying to use the original? It's a multi switch inside and sounds like it's out of line for some reason.

Thanks Chief. The stem was fully seated. I used my original stem as the switches do not come with stems. The first one went right in and worked as it was designed to do, had to depress the spring button on top to get it to come out. Second one, the more expensive one, was so wide that the stem didn't seat. I could see that the parking lights were on in the fully pushed in position though.....

Guess I'll have to place an LMC order to get it right......

[Bkndsdl]

So doing a bit of digging, the LMC catalog lists my switch as part number36-0626, and my son's 1980 c10 switch as 36-0627......so I am thinking I may be getting the wrong switch. Of course, the 67's is backordered............ and the switches at the parts house have no markings on them whatsoever to determine if they are giving me the wrong part......guess I'll try a new parts house. Or ask for a square body switch, lol.......

[GMCPaul]

1967-72 Headlight switch, GM used 2 different styles.
1967-68 8-Terminal headlight switch
or a 1969-72 7-terminal headlight switch.
Note- 1967-68 the front park lights go off when headlights turn on using original style switch, if you want the front park lights to stay on with headlights choose the 7 terminal headlight switch as they are interchangeable.

If your using a 69-72 version you should still have functioning lights so there is a good chance you have other issues. Per above you can identify the 67-68 switch by its 8 terminals and the 69-72 by it's 7 terminals.
Paul Jr @ GMCPauls

[RustyPile]

I'm with GMCPaul on this one.. Two switches from two different manufacturers?? Same symptoms?? You have wiring issues, not switch problems. The question remains -- what were the symptoms that led to replacing the original switch??

['68OrangeSunshine]

'67-Only -- First notch out = Parking Lights ON
Second notch [all the way] = Headlights ON, Parking Lights OFF.
For model year 1968, the Federal government mandated the Parking Lights to become Running Lights, and stay on with the headlamps.
Also the Side Marker Reflectors were mandated.
With model year 1971, they were made Side Marker Lights, and the front ones blinked opposite to the Turn Signals.

[Bkndsdl]

Problem solved; after going to another parts house, the part they gave me worked perfectly. The original parts house must have the wrong part in stock for my year........

Incidentally both parts from both stores looked absolutely identical, both 8 blade terminals and all. Just one store has their parts listed correctly I guess....anyhow, Jake's back on the road. Thanks guys!

[Palf70Step]

Good to hear that!

[toolboxchev]

There is at least 2 to 3 different versions of the underdash wiring harness I have found.

Sometimes those ends to plug get confused. Use the wiring diagram in the electrical area. Bet you figure it out then....its a good diagram and you can trace everything by color.

['68OrangeSunshine]

I changed out the Head Light switch last night on my '68 C/10. Problem was with the rheostat making incomplete contact thru the whole arc. New switch, dash lights are good from black to brightest. No flickering out.
My '68-and-Later switch has 8 contacts, [not counting the wider (5/16'') male contact for Ground on the side]. Same type as the old one.
I noticed female contacts for Terminals 3 and 7 were absent on the factory Head Light Switch plug.
Also the pull-thru from Off to Headlights has a slight resistance at the middle.
Hoping this will wear-in, rather than be a manufacturing flaw.
Works OK.
Duralast SW141, p/n: V19009, Switch, Interruptor.