240Z Turn Signal Switch Circuit Modification

Contributed By: Peter Paraska, IZCC #15

240Z Turn Signal Switch Circuit Modification

(Copyright by Peter Paraska. Donated to the IZCC and Public Domain by Pete Paraska. Distribute to anyone interested but don't charge a thing.)

The following is my modification of the turn signal wiring for 240Z's. I made this modification in order to take the current load off of the turn signal switch and put the load onto two relays.

My 240Z's turn signal switch was constantly going bad - the symptom was that the dash indicator turn signal lights and front turn signal lights would work, but the rear lights would not (unless I held the switch all the way up or down). When I would take the switch apart, the contacts were fouled, causing high resistance.

(From looking at the wiring diagrams for the 260Z and 280Z (in Haynes), a different switch and wiring scheme is used. On these cars (260Z,280Z) it ought to be much simpler to modify, since it is only a single pole double throw switch, with a center "OFF" position. All the fancy switching that goes on inside the 240Z turnsignal switch is apparently handled elsewhere in the 260Z and 280Z.)

The original turn signal switch in the 240Z is a not a standard type of switch. I don't think you could apply a term like DPDT to it. It's kind of like a 4PDT switch with a center "OFF" position, but not quite, since some of the contacts are "shared" across poles. Since I didn't know if a relay was available that would work the same way as the switch, I ended up using (2) triple pole, double throw relays.

Original circuit:

(This page last revised on: 19 December 1998)