original circuit/headlights no worky

[ferd289]

289/v8 s30 conversion.  My headlights do not turn on when combo switch turned on.  All rear light work great. 

I checked combo switch terminal box with the 4 wires, for power at w/r wire, when switch turned on is ok 12 v. Checked red wire shows that it is a ground no voltage should be correct. 

I read where headlight circuit gives power to headlights via a ground through the dimmer switch.  Headlights turn on when I feed 12v power to them with my power probe so i think the circuit is fine. 

Can anyone tell be how I can get a ground to the headlight circuit without a dimmer switch, iow, is there a terminal on the combo switch area (i.e. c9 plug) that I can run a ground wire to to allow a ground for the headlights to work.

I get full voltage at the combo terminal box with the w/r and r and 2 gr, but 11.4 at teh circuit for the parking lights ( prolly seperate issue just needs terminal cleaning )

Tks

Edited December 8, 2020 by ferd289

[NewZed]

25 minutes ago, ferd289 said:

I read where headlight circuit gives power to headlights via a ground through the dimmer switch.  Headlights turn on when I feed 12v power to them with my power probe so i think the circuit is fine. 

 

Can anyone tell be how I can get a ground to the headlight circuit without a dimmer switch, iow, is there a terminal on the combo switch area (i.e. c9 plug) that I can run a ground wire to to allow a ground for the headlights to work.

 

 

Not really clear what you did here.  You said they come one when you give them power but you're asking about the ground side.  Do they need power or do they need ground?

 

Most headlight problems are at  the dimmer switch as you mentioned.  People have good luck by spraying contact cleaner down in to the dimmer mechanism and working the switch.  Worth a shot.

[Sjoost]

Fred,

 

Are they LED headlights or just normal stock?

 

joost

[ferd289]

 normal stock lights.  They both work when I provide 12 volts to the circuit (on the fuse box) with power probe.  Is the dimmer switch somewhere on the combo switch, I don't know where the dimmer switch (contacts ) are?  

Also, when I check the voltage from the front parking light circuit I get 11.4 volts when battery is 12.8.  I am going to clean all the contacts on the front circuit ( headlight and parking light) connectors today.  Maybe the issue is the voltage to the front headlights is low.

Tks

[jhm]

The high/low beam switch is integral to the turn signal stalk, which is part of the Combination Switch assembly.  Sounds like you don't have access to an FSM.  I don't know what year your car is; but you can download complete FSMs for all years, free, at:  http://www.xenonzcar.com/.

 

The "Body Electrical" chapter includes detailed schematics of all circuits, switches, and harnesses.  As @NewZed suggested, oftentimes the problem is resolved by simple cleaning of the switches and contacts. 

[ferd289]

will do tks

[jhm]

Forgot to mention that your lighting system (both running lights and headlights) will benefit greatly from the addition of modern relays in the circuitry.  You can wire in your own relays, or purchase pre-fab kits from Dave Irwin (https://www.datsun-240z-upgrades.net/) or MSA Auto. 

 

Benefits include better current flow to the bulbs (directly from the alt/battery), and less amps flowing through the 50 year-old combo switch.  These upgrades are particularly important if you're still running old-style bulbs and sealed beams, but they make sense also for anyone that's upgraded (e.g. LEDs, etc).

[ferd289]

tks , i plan on installing a relay for the headlights.  Now I am going to clean all the front end terminals after seeing 11.4 volts at the terminals for  the parking lights up front.  In order to restore the the 4 wire junction box ( w/r,solid 'r', 2 greens) up by the steering colume, do i take it apart or acquire a new one if necessary.  I did a continuity check on the w/r and red wire with combo headlight switch open and closed.  No continuity.  Does this mean I have to get a new switch?  

[NewZed]

That is a common failure point.  The contacts inside the switch get pitted.  Sometimes the switch gets so hot that the solder joint on the top breaks.  Be careful with those wires, the joints are probably fragile from the many heat cycles.  Typically, the contacts inside get pitted and/or the wires break off of the top.

 

You can take it apart and clean it up and probably get it to work again.  If you do get it working then relays will take the high current load off of the switch.  You need that switch to work, even to use relays.

 

Bend those four little tabs back and the board will come off.  There are springs and balls inside if I remember correctly.  Don't lose them, do the work over a container or on a large work bench.  There are threads around the internet about repairing it.  I'll post one if I find it.

 

Forgot to say that some people desolder the wires and flip the board around.  One set of contacts is unused on the board.  But if you can clean up the old contacts they should easily handle the .3 amps of a relay.  The running lights are handled there also and that circuit goes bad often also.  Relays everywhere are good.

Edited December 9, 2020 by NewZed

[ferd289]

thanks, will do.  couple of pics to show what I am working with for fun.

[NewZed]

I'm guessing you'll have no problems with the relays.  I put one between the switch and the fuse box to start just to take the load off the switch you're about to work on.  But there are other ways.

 

Found a good thread with pictures.  Notice the extra set of unused contacts..  Nice and clean.

 

https://www.zcar.com/threads/headlight-combination-switch-repair.311982/

 

[Miles]

https://www.kamikazeracing.org/dl/ZTech/Rebuild_240Z_combo_switch.pdf

 

 

 

[ferd289]

tks Miles, Newzed and all that contributed.

Edited December 11, 2020 by ferd289