A Different Headlight Relay Upgrade - 4 Relays

[TomoHawk]

Don't forget, if you have a 280Z, the headlamp wires are different for each lamp.  For example, the  right lamp has red for the common +12, but on the left, it's the RY.

 

From the FSM:

 

Edited July 2, 2015 by TomoHawk

[Captain Obvious]

TomoHawk,

 

It's more complicated than that... In 77 and 78 they used the same short headlight pigtail on both sides from the bulb back to the engine bay harness. So while my 77 has a Red coming out of the harness on the pass side and a Red/Yellow on the driver's side, both sides are the same color (Red) after they pass through the three position connector to the short pigtail length to the bulb.

 

In other words, the colors on my diagram above are correct. At least for 77 and 78.

 

I don't know about the other years, but since there really isn't any difference in the pigtail for either side, I would be surprised to hear Datsun actually assembled different ones for each side in any year. Just no good reason to spend the extra money to build, stock, and use two different versions.

 

Are the short pigtail wire colors different on each side of your car?

[TomoHawk]

I would have to dig out those wires.  I do know that my wiring diagram has been correct on everything so far.

[Captain Obvious]

Take a look when you get the chance. I'd be surprised, but it would be good to know for sure.

 

The connectors and short pigtail lengths didn't even show up on the earliest wiring diagrams, and then in the later diagrams, the connectors and pigtails made it to the wiring diagrams but the wire colors aren't noted on the pigtail. The engine bay harness has R and R/Y, but the pigtail colors aren't labeled.

[Captain Obvious]

I just took a look at the wiring diagrams.

 

The pigtail connectors didn't show up at all until 74 and the colors of the pigtails were never listed.

[Namerow]

I have a brand-new LHS headlight assembly sitting in front of me (PN 26060-E4601).  According to carpartsmanual.com, this (and the matching RHS assy) were used up until July 1973.  Some details, for those interested:

• Pigtail length (exposed length, from exit of headlamp bucket to start of white connector plug):  23"
   
• Wire colours (continuous, plug-to-plug):
  • RW -  hi-beam... marked 'Drive' on the lamp-end, black connector
  • RB  - lo-beam... marked 'Pass'
  • B    -  ground...   marked 'Ground'
• All 3 pigtail wires are 16GA  (which is interesting, given that the 'arriving' wires from the engine harness are 10GA, 12GA and 14GA)
   
• T-connector terminals (viewed from plug-in face):

                                   LAMP PLUG           HARNESS PLUG

        Top                            RB                             B

        Bottom-left                RW                            RW

        Bottom-right                B                              RB

 

In other words, the B and RB terminal positions switch places from lamp plug to harness plug (necessary to let Nissan mate it's oddball headlamp switching/grounding arrangement to the standardized terminal positions on a sealed-beam headlamp unit?).

 

Unfortunately, I can't find my RHS headlamp assembly at the moment, so I can't verify directly that the pigtail is the same.  I do know, however, that the mating headlamp plugs on the engine harness use identical wiring orientations, LHS to RHS.  That is, the LHS and RHS plugs are not mirror images.  Instead, both have the RW wire located on the driver's side and the RB wire on the passenger side.  This same-ness is reflected in the wiring diagram.

[Captain Obvious]

The 77/78 pigtails kept the same wire gauges all the way to the bulbs which makes more sense electrically. In theory, they could cut the gauges on the pigtails some because each side only carries current from one bulb instead of two, but they kept them all the same.

 

I've seen that printing on the back of the headlight connectors as well. Makes me think that at one point the plan was to run the headlights with the common connection to ground. I doubt Nissan molded their own connector shells, but the people who made them were thinking that common to ground was the intent.

[TomoHawk]

Bruce-   I'll PM to you a copy of my wiring diagram file.

 

To me, it makes sense to decrease the size of the wire as the distance from the battery increases.  The first wires from the battery carries the most current (starter motor, etc.) then you go to the alternator,which slowly recharges the battery, then to the accessories, (heater motor,) lamps, and then fuel injectors, small bulbs, etc. (smallest size wires.)

 

the frear window defroster seems to be an exception.

Edited July 3, 2015 by TomoHawk

[Namerow]

Both the metal headlamp bucket and the black plastic connector for my headlamp assembly are labeled as 'Koito' (stamped into the metal part, molded into the plastic part).  FWIW, the brass wire-end terminals at the lamp end of the pigtail are all the same size.  Same goes for the brass wire-end terminals at the harness end.

[Captain Obvious]

TomoHawk, Thanks for the wiring diagram. If you get a chance to look at your pigtails, let us know.

 

Namerow, That's another change they made in later years. The 77/78 connectors between the engine bay harness and the pigtails is different than previous years and not all of the contacts are the same size. At the bulb end, mine are all the same size, but at the harness end, the R/W (high beam) is larger than the other two. Doesn't really make electrical sense and I would have told them there's no benefit, but I wasn't there when they designed it.

[TomoHawk]

These are the colors of the wires from my headlamps.  The first one is the heavy wire.

 

Wire #1:
rw
rb
red

Wire #2:
rw
rb
red

[Captain Obvious]

Yup. That's the same thing I've found as well. Thanks for checking.

 

So somewhere along the way they changed some of the wire gauges sizes and the color of the common connection wire (from black to red), but I don't think the pigtails ever used "side specific" wiring colors.