67 Signal Switch, It's all in the cam, part 2

[Gerard F.]

Last week at the Tahoe Regional, I was having trouble with a repro 67 signal switch which I had put on my 67 only about 5 months ago. Everything worked OK, the right and left signal, the hazard flash, and the brake lights.

However, whenever I turned the Ignition on (or accessory) both rear tail lights would start very dimmly blinking through the signal flasher, and the signal flasher would start clicking. The solution was to change the switch before I left for home, with one I had repaired and had with me.

Well I got home just fine and figured I'd do a little investigating on why this 5 month switch was going haywire. Ohmed it out and found that there was some sort of short in the cam between the signal flasher feed and the brake light contacts. So I pried up the cam and this is what I found:



Grease, Grease, Grease, add a little carbon from the tang burning against the contact, and I guess you have a short.

Cleaned it up with some Q-tips, electrical contact cleaner and a Dremel with a poly brush:



Put the cam back on and ohmed it out. Seems to now work just fine, but I'm not trusting it. I just ordered the new Shee-Mar one made in Colorado. But before I put it on, I'll blow out all that factory grease with contact cleaner.

This is a pretty sophisticated switch. If you ever want to troubleshoot one, here's a schematic diagram:



One of these days I'll finish the story I started on the signal switch, but I'm having too much fun in the meantime.

[Jim T.]

Re: 67 Signal Switch, It's all in the cam, part 2

Gerald appreciate your earlier and present postings on your 67 turn signal switch.

My 68's turn signal switch will not lock in the left or right positon. Works great either direction when it is held.

From your experience is replacement the only option?

[Gerard F.]

Re: 67 Signal Switch, It's all in the cam, part 2

Jim,

Replacement is not the only option. Sounds like the little hold back ears on the cam are broken on yours. The usual problem. See my previous post about a new cam in town.

Don't have Shee-Mar's number handy, but you can google it. Call them up ( don't order online) ask for the new SM-15 replacement cam, the red one.

You don't have to pull the switch off the car to replace the cam, if you are handy with a soldering iron, shrink tubing while working in the drivers seat. On a 68, it is a lot easier to pull the switch then on a 67.

You might get a replacement switch just to have handy, in case you need it in a hurry.

[Larry M.]

Re: 67 Signal Switch, It's all in the cam, part 2

Jim,

Replacement is not the only option. Sounds like the little hold back ears on the cam are broken on yours. The usual problem. See my previous post about a new cam in town.

Don't have Shee-Mar's number handy, but you can google it. Call them up ( don't order online) ask for the new SM-15 replacement cam, the red one.

You don't have to pull the switch off the car to replace the cam, if you are handy with a soldering iron, shrink tubing while working in the drivers seat. On a 68, it is a lot easier to pull the switch then on a 67.

You might get a replacement switch just to have handy, in case you need it in a hurry.

Jerry:

Is your repro switch the one that was recently released by "thepartsladi" that was made off the original Delco tooling here in the US? I know a number of folks (self included) that purchased one as a shelf spare. The same part was/is being sold by many other Corvette suppliers as well.

Do you feel that the Shee-Mar switch is the best one currently on the market? I have generally heard good comments regarding their switches....but if I recall, even they did not have the 1967 Corvette switch a while ago.

Larry

[Gerard F.]

Re: 67 Signal Switch, It's all in the cam, part 2

Larry,

The last two switches I had trouble with, including the one in the post above, were from the partsladi on ebay.

I just received the one from Shee-Mar today, so I really can't say whether it is any better or worse. It sure looks like the partsladi one, but looks can be deceiving.

I think this switch is new to Shee-Mar as well as the SM-15 replacement cam. They say it is made from the original Boyne switch blueprints in the USA. For all I can tell from looking at it, it could be from the same manufacturer.

[Gerard F.]

Re: 67 Signal Switch, It's all in the cam, update

Larry,

Did a real close inspection of the partsladi switch and the Shee-Mar switch side by side last night. Noticed the same little casting marks and defects in the body plastic, and concluded that they were cast from the same mold.

Same riveted electrical connections, although a slight variation in the wire colors between the two. The Shee-Mar one seems to have the a slightly
tighter fit between the cam and the body, and lacks the gobs of grease on the contacts between cam and the body (my nemesis on the last one above).

Looks to me that the plastic castings came from the same place, although they may have been assembled in different locations.

One thing I would check on your spare switch is the existence of globs of grease on the contacts between the cam and the body. Pry up the cam off the body and clean all the grease out, maybe just put a light coat of dielectric grease on the contact points for corrosion protection.

[Larry M.]

Re: 67 Signal Switch, It's all in the cam, part 2

Jerry:

Thanks for the information, and for taking the trouble to post (w/pictures) to help others avoid similar problems. I will definitely check my switch for the excessive grease.

Thanks again, Larry

[Terry M.]

[Dale S.]

Re: 67 Signal Switch, It's all in the cam, part 2

Thanks again Jerry for your attention to details. I hope my original never breaks. I think I will quit using my turn signals( Save the switch). Most of the drivers in New Mexico DO NOT use turn signals. Dale

[Gerard F.]

Re: 67 Signal Switch, It's all in the cam, part 2

Dale,

If you don't use the signal switch, just make sure you keep checking your brake lights. The brake light feed, as well as the hazard flasher and signal flasher feeds, all go up through the signal switch on a 67 (also 68) and get distributed through the cam in the picture in the post above.

If you get a short or burn in the inside tang of the cam, or contacts on the switch body, you won't have any brake lights and you will not know from the driver's seat.

Guess how I know this? Almost had a rear end hit because of the switch.

Cheers,

[Dale S.]

Re: 67 Signal Switch, It's all in the cam, part 2

Jerry, Thanks for the heads up. I will check it. Dale

[Gerard F.]

Re: 67 Signal Switch, It's all in the cam, part 2

I hear ya, Terry.

I actually started one a number of month's back, but then got to having too much fun on other things. You know how it goes

Now with the new failure, and a third switch, I guess I'll finish the story in the next couple of weeks.

[Jim T.]

Re: 67 Signal Switch, It's all in the cam, part 2

Dale,

If you don't use the signal switch, just make sure you keep checking your brake lights. The brake light feed, as well as the hazard flasher and signal flasher feeds, all go up through the signal switch on a 67 (also 68) and get distributed through the cam in the picture in the post above.

If you get a short or burn in the inside tang of the cam, or contacts on the switch body, you won't have any brake lights and you will not know from the driver's seat.

Guess how I know this? Almost had a rear end hit because of the switch.

Cheers,

If the fiber optics are in good working order on a 68 you can visually see that the brake lights/taillamps/turn signal function work from one left or right rear light from the drivers seat.

[Gary J.]

Re: 67 Signal Switch, It's all in the cam, part 2

Jerry, have you tried ordering one from NAPA to see if there any difference in the ones you already have. I don't know but it could or could not be foreign junk!

[Dale S.]

Re: 67 Signal Switch, It's all in the cam, part 2

As always thanks for your help Jerry. Dale