Technical 1957 Oldsmobile Electrical Gremlins

Dear H.A.M.B-er's
Once again I need to draw on the vast knowledge pool this group treads in..
Issue is: 1957 Oldsmobile. New wire harness. Recently replaced turn signal switch (nos). At the point of installation the turn signals worked perfectly. Now the owner (my friend) reports that the signals work fine but when either the park lights or headlights are on, the turn signals do not work??
I looked at the wiring diagram for an Olds of this circa and it appears to me that the light circuit and the t/s circuits are completely separate except for the shared bulbs, which of course have two filaments. Any thoughts other than getting a new friend. (He calls upon me just because I have a volt meter and a test light!)
I relish any direction ( and the assorted quips/barbs which will also appear) you can offer to help me sort this issue out.
MrPhat40

 

Weirdness like this is almost always due to one or more poor grounds if the new harness is wired OK. Jack E/NJ

 

I would check grounds at every light.

 

Grounds and make sure the button in the sockets are lined up correctly. Add a dab of dielectric grease to the bottom and side of the bulbs

 

Yup, Grounds on the light bodies. I have had this time and again on cars. Check the tail light housings and see if there is a good ground on them. Do the same with the front signal bodies. Also a shorted filament inside a bulb can screw up everything and drive you nuts. Please report back when you find the cause.

 

Another for the ground. Worked on a 56 Olds that did the same thing.

 

Thanks for the input
I will check and clean all grounds and make sure the bulbs are all good
Most likely will not get to it until next week
Rest assured I will let all know what I find
Appreciate it guys
MrPhat40


Sent from my iPhone using The H.A.M.B. mobile app

 

To all who chimed in.
I found the issue taking your cues. It was a "halogen" taillight bulb causing the erratic turn signal operation.
While each filament worked on their own, when the park light filament was lit a shunt between it and the turn signal caused a voltage drop causing the issue.
In any event a new bulb solved the case.
Thank you all once again for your help.

 

Glad you got it fixed, problems like that can drive you nuts. Thanks for letting us know what fixed it. Brian

 

Without going back to refresh my memory via a wiring diagram things had to be just so or it didn't work right at all due to how the circuity was designed. This made things seem more complex that what the problem actually was.