280Z High Beam Switch Repair

[Zed Head]

Looks like a decent quick-fix.  I think you end up with both filaments on, high and low, when the high beams are on though.  So more current than normal passing through the HL fusible link.  Might be more for the switch on top of the column also, if I recall right.  That switch already gets hot with just one beam circuit running through it.  Might melt if you run high beams for long.  Unless you put a relay at the fuse box.

Good old Big Phil...

[gundee]

1 hour ago, TomoHawk said:

Yes, I've seen that.  It's st00pid. 

What he does is to ground the low-beam side of the headlamps, so they are on, regardless of whether you switch on  the high-beams.  It's not a repair, just a cheap fix that bypasses the high-beam switch and could overload the headlamp switch or fuse.  I would only do that in an emergency situation.

No. Look at your 280Z wiring diagram again. Low beam will turn off.

[TomoHawk]

Read post #13 please.

[TomoHawk]

On 10/3/2018 at 6:56 PM, Zed Head said:

Looks like a decent quick-fix.  If I recall right, that switch already gets hot with just one beam circuit running through it.  Might melt if you run high beams for long.  Unless you put a relay at the fuse box.

Good old Big Phil...

My switch has never been warm, but mine is fairly new.  I think what you refer to is an older switch or from an early Zed.  It's still not a good idea to have both low AND high beams on through that switch.

Edited October 19, 2018 by TomoHawk

[Zed Head]

1 hour ago, Lumens said:

No. Look at your 280Z wiring diagram again. Low beam will turn off.

Big Phil shorted the low beam so that it always has ground whenever there is power.  You have to watch the video.  The low beam will always be on by Big Phil's video "fix".   It's shown in the wiring diagram.

[Zed Head]

30 minutes ago, TomoHawk said:

My switch has never been warm, but mine is fairly new.  I think what you refer to is an older switch or from an early Zed.  It's still not a good idea to have both low or high beams on through that switch.

The problem with the switch is well-documented for all of the Z's.  They pit, then get hotter, then the solder joint fails.  Wasn't talking about your newer switch.

If you want to drive your car in the city and you can't use high beams because of other cars then Big Phil's fix will work.  If you decide to use the high beams you run the risk of damage.  But low beams will be just like normal, except grounding at a different point.

Good luck with whatever you do.  

The simplest fix, of course, is to find the original problem before deciding on a "fix".  Even Big Phil knew that his real problem was somewhere in his wiring harness.

Edited October 4, 2018 by Zed Head

[gundee]

2 hours ago, Zed Head said:

Big Phil shorted the low beam so that it always has ground whenever there is power.  You have to watch the video.  The low beam will always be on by Big Phil's video "fix".   It's shown in the wiring diagram.

Yup you are correct. I thought Big Phil jumped the connection that ties both headlights together to upstream B/W ground. He needs to do that as the return path has to get back to the Hi-Lo switch.If that still does not do it then he should jumper the next connector further upstream back to the headlights from what I can see. And if not one of the connectors bad, then a broken R/B wire somewhere along the path. I think Lucas had a hand in this design.

[TomoHawk]

In stead of wiring it "permanently," as in the video, I'd suggest using a switch at that point, so if you think you will be using the high-beams, you can switch them on both on for short periods,  or switching off the low-beam temporary ground for extended high-beam use.

Edited October 13, 2018 by TomoHawk

[TomoHawk]

On 10/3/2018 at 2:20 PM, Zed Head said:

Did you bypass the switch to see if it's causing excess resistance?

Yes. I made up a heavy shunt to the chassis and plugged it into the terminals for the high-beam switch, and AFAICT, there was no noticeable difference.  I also tested the resistance across the switch, which also showed no  or very little resistance. Then I got out my can of eOxit-100 and started cleaning all the terminals, plus the ones on the firewall junction block, just to make sure every terminal to the entire car was cleaned.  I was looking for the wires that went to the headlamps.

Then, I noted a large 6-terminal connector, like the one for the tail lamps, which had 10-gauge wires going to it, matching the color codes for the headlamps!  I treated those terminals with DeOxit and turned on the headlights. 

It seemed brighter in the garage, but it was day, and not very  dark, inside even with the door down.  After I get the steering wheel on, I'll take it out at night and check it in the driveway (which is 250 feet long, and the door has lines that align nicely with the headlamps for aiming.

I'll get you a photo of the connector.  it seemed to be hiding behind the junction block, and I hadn't noticed it until now.  I'm surprised that it's not mentioned in the FSM, but the Diagram is on page BE-16, and he connector ID is C-9 (highlighted by the red arrow in this graphic.)

What I think is odd is that only some of the headlamp wires go though connector C-9 and others go through the smaller connectors in the junction block.

Edited October 19, 2018 by TomoHawk

[TomoHawk]

I finished the work on the headlamps, and I think they are brighter now.  I cleaned (de-oxidized with DeOxit 100)  the large C-9 connector by the junction box, and the connectors for the beam switch, and the multi-pin connector- both underneath the steering column.  They had showed some black stuff on the plastic around the (round) pins, which I think might be from some overheating.  But after de-oxidizing, thee pins were brighter, so they should not get so hot.

Here is a photo of the C-9 connector, highlighted in yellow.

 

Edited November 5, 2018 by TomoHawk

[TomoHawk]

So...

I removed the high-beam switch from the car to test and clean it on  my workbench, and the thing was stuck on high-beam.  Even if you switch it to low-beam, when you probe the switch terminals, it's still on high-beam. 

You can send the switch to ZCarSource, who I believe owns what was left of MSA's inventory, and along with their machining and technical department,  can rebuild your turn signal/high-beam switch for about $200.  I bought a used switch from an eBay seller, and hopefully it will get the car to a working condition for another year.

Rod's Datsun Parts in  Los Angeles will sell you a used switch for $300, so I'd rather have a used one rebuilt.

Other than that, you will have to eventually retro-fit an antique or aftermarket turn signal switch with a high-beam function.  Fortunately, the connections to the main wiring isn't that complicated.

[Zed Head]

Not sure what Nissan calls it but most of us call that the "dimmer switch".  The power supply switch is the combination switch.  Edit - actually Nissan calls the whole assembly the combination switch.  But they do break it down in to sub-switches.  Picture below.  Dimmer.

I thought the dimmer switch was pretty simple, parts-wise.  Mine was "stuck" at no power to either circuit but dousing it with DeOxit and working it back and forth fixed it.  Not sure how it could get stuck on high.  I thought it was a toggle switch.  If the lever moves, the switch contacts move.

Anyway, I found some new news while I was looking for old pictures of what people have done with the dimmer.  Dave Irwin has moved to Montana and doesn't rebuild switches any more.

https://www.datsun-240z-upgrades.net/

Edited November 16, 2018 by Zed Head