Turn Signal Repair

If you have a first generation Z car, you probably are dealing with turn signal issues. The left side doesn’t work. The right side doesn’t work. Only the back turn signal flashes, etc.

I got my hands on a new turn signal switch for my 260Z, and I installed it a couple of months ago. Of course, I tore apart the old one to see how it worked. I wanted the learning experience, and I thought it was a good idea to rehabilitate the old switch as a spare or perhaps to sell. I took it apart, cleaned it, and put it back together. (There were n0 extra or missing pieces, either!) I tested it, and I was happy with the results. I even tried out a few ideas on restoring the stalk. (Tip, PlastiDip doesn’t work well for this application.) I’m close, but I’m not happy with the results, yet.

While hanging out with the Z crowd at Caffeine & Octane, I told my friends about my work on the old switch. Pete directed others my way as they mentioned the issues they had. I found that they did have issues with their switches. I told Lee how his could be fixed, and Larry asked me if I could fix his. I agreed, and he brought his switch to the next meet.

There are three different part numbers for US Domestic Market S30 turn signal switches.
25540-N4600 – 1970 & 1971 240Z
25540-N3300 – 1972 & 1973 240Z
25540-N3605 –  1974 through 1978 260Z & 280Z
(Note: I use model years for simplicity. I do not have independent confirmation of production cut-offs for parts.)
In the 240Z, the brake light circuit is shared with the turn signals. In the 260Z & 280Z the brake light circuit is independent of the turn signals.

Here is the turn signal switch before I worked on it. Note the dirt and corrosion from 40 years of use. There is plenty on the inside, too.

TurnSignal_Repair_38 The turn signal cancellation tabs seem prone to collecting dirt to the point where the spring will not pull them back into place. Fortunately, that is easily fixed.
Here are a 240Z switch and 260Z/280Z switch side-by-side. You can see the 240Z switch has 6 wires on it, and the other switch has only 3.
For the 240Z switch, position 5 is the voltage source for the turn signals. Position 2 is the voltage source for the brake lights. You can easily test the switch with an ohmmeter. Assuming left turn is toward position one, here is the resistance in Ohms that you should get for a properly functioning switch between each pin.

Switch position 2-1 2-3 5-4 5-6 5-1 5-3
Neutral >1 >1
Left Turn >1 >1
Right Turn >1 >1

1. Remove the screws that hold the turn signal contacts to the switch body.
2. Remove the screws that hold the high beam switch to the switch body.
3. Remove the screw that holds the horn button contact to the switch body.
4. Spread apart the bracket that holds the wires to the switch body.
In the pictures above, screw 1 is for the high beam switch, 2 is for the turn signal contacts, and 3 is for the horn button contact.
4. You can now separate the contacts with wires from the switch body.
5. Place the turn signal contacts on a flat surface with the button facing down.
6. Use a small screwdriver to pry up the three tabs that hold the board to the case. Dave Irwin also suggested using wire cutters.
7. If necessary, use long-nose pliers to straighten the tabs out just a little more to free the board from the case. Bend the tabs as little as possible. They can and WILL break. Take care when separating the board and the case that you do not lose the ball bearing that is inside.

On the inside of the board, you will see two rockers with contacts. The rocker perpendicular to the board is for the brake lights. When you move the switch, the button pushes the rocker back, breaking contact between the rocker and the brake light contact for that side. The rocker that lies flat is for the turn signals. It is held in by the two tabs. You might need to separate them slightly to get the rocker loose. If you have a typical switch, you will find plenty of carbon build-up on the underside of the rocker where it makes contact with the turn signal branches. The contacts on the board will probably be coated with carbon, too.

I used a variety of chemicals/techniques to clean the switch components including
1. Permatex Rust Dissolving Gel
2. Purple Power Degreaser (I am thinking that the alkaline nature of PP is good to neutralize the rust dissolving gel.)
3. Brake cleaner – great for blasting the dirt out of the pivots for the turn signal cancellation
4. Denatured alcohol (Should help remove any residual water and evaporates without a residue.)
5. 800 grit sandpaper to remove the stubborn carbon buildup. I sanded the contacts between the rocker for the brake lights and the rear lights since I couldn’t easily get any chemical cleaners into the gap.
6. White spray grease to lubricate the moving parts on the switch body. Just use it sparingly, like it cost a million dollars, and do NOT use it near any of the electrical contacts.
I did experience some excessive stiffness/lockup in the switch body after cleaning it, but patience and spray grease prevailed.
7. Metal polish – I used Mother’s Metal Polish, but this is just for aesthetics. Be sure to remove it thoroughly after buffing (denatured alcohol works great) to prevent leaving material on the contacts that could carbon up faster.

Reverse of disassembly.
1. Place the turn signal case so that the opening is up.
2. You may want to stretch slightly the spring that pushes the ball bearing against the rocker and put the spring back into the detente in the sliding button.
3. Put a dab of dielectric grease on the end of the spring and place the ball bearing on top of the spring. The grease should hold the button in place.
4. Place the rocker for the turn signals on the board. Check to make sure all of the contacts touch the right spots. I had to bend down the arms for the front turn signal contacts. I also bent the rocker slightly to ensure it would not make contact at the wrong time.
5. Once the rocker is in place with the arms for the contacts properly adjusted, make sure the tabs holding it in place are not too tight or too loose. The tabs should just keep the rocker from shifting around.
6. Move the button to the center of the case.
7. Flip the board over and press it against the case.
8. Bend the middle tab back into place and then repeat with the outer tabs.
9. Move the button and check resistance to ensure the switch is functioning properly.
10. Reattach the contacts and high beam switch.

If all went right, you should have a functional switch.

This entry was posted in 240Z, 260Z, 280Z, Electrical, Tech Tips. Bookmark the permalink.

23 Responses to Turn Signal Repair

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  8. Steven Klein says:

    NICE! Did you try to repair the high beam plastic switch? You have a working one for sale? Cheers!

    • I have taken the high/low beam switch apart and cleaned it. It’s more of a challenge to thoroughly R&R one. I probably have a spare high/low beam switch. What year do you need?

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  14. Simon says:

    Hi there! I read your article and have the following question: Would it be possible that I give my switch to you to repair it? I would of course compensate you for your work! Best, Simon

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  17. Robert Bohl says:

    I recently purchased a 1972 240Z that has been restored and modified by the previous owner. I am also the original owner of an almost stock 1971 Z. My problem may be a simple one as my switch works, however the stalk is positioned so that it is always pointing down, as if to signal LEFT. In the RIGHT position it sticks straight out (as with my ’71’s neutral position); and when you signal LEFT the stalk almost hits your knee. The stalk appears to ,be attached to the switch with a single pin not a screw, and to be 45 degrees out of rotation. How can the stalk be removed so that it can be repositioned without breaking anything? Thanks.

  18. The turn signal switch clamps to the steering wheel with the headlight switch, utilizing two screws. One screw should be at the top of the steering column and the other should be at the bottom. If someone played mix & match (different years) between the turn signal switch and headlight switch that could cause the two halves not to align properly. You might want to take the cover off your steering column, take some pictures and post them at http://www.classiczcars.com. Then the peanut gallery can give their assessment.

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  21. parsethis says:

    Awesome instructional. Did this to my turn signal assembly last night to resolve the characteristic smoke-from-the-column issue. Cheers.

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