Lights, horn are dim

[Richard McDonel]

1971 240Z. My headlights, dash lights, and horn all work, but not well. Headlights are dim, dash lights are barely there, and I doubt the horn could be heard from 100 feet. Fuses are OK. Any ideas? Thanks

[Patcon]

Have you checked voltage at the devices?

[siteunseen]

Sounds like loose or dirty ground somewhere but that would be too simple. My horns did that before and I just filed the grounds up nice and shiny and it scared me when I pushed the horn pad. Never heard them so loud since owning the car. Hopefully it's something easy, good luck.

[SteveJ]

9 hours ago, Richard McDonel said:

1971 240Z. My headlights, dash lights, and horn all work, but not well. Headlights are dim, dash lights are barely there, and I doubt the horn could be heard from 100 feet. Fuses are OK. Any ideas? Thanks

Let's take this apart.

All three systems are on different circuits. As long as you have a good battery, and your alternator is putting out over 13VDC, voltage would not be an issue.

The current for the headlights passes through the combo switch. The current for the parking lights also passes through the combo switch but through a different set of contacts. Years ago @Zs-ondabrain developed nice relay kits for the headlights and parking lights (The dash lights are on the same circuit as the parking lights.). These relay kits are sold through Motorsport Auto. Here are the links:

Headlights: https://www.thezstore.com/page/TZS/PROD/12-4651

Parking Lights: https://www.thezstore.com/page/TZS/PROD/12-4652

These relay kits take the load out of the switch.

Also, swapping the bulbs in the dash lights for LEDs can make them much brighter. The downside for some people (not me) is that you probably can't dim the lights unless you change the rheostat for a PWM. I am good with the gauges being bright.

Now for the horns...When I was waking up my 240Z after it's 9 year slumber, I was going through the different systems and found the horns weren't working well. I ordered some new horns and a horn relay, but I figured that I would also inspect the old horns. When I removed them, I found corrosion on the positive terminal and where they bolted to the car. The latter is the grounding point. I used a narrow wire brush on a Dremel to clean the grounding points, and I wire-wheeled the positive contacts, too. I reinstalled and found I had strong horns again. If cleaning the contacts does not improve things, it could be the horn relay. Apparently, horn relays for 240Zs are becoming scarce. ZCarDepot still has OEM relays. You can get the part number from CarPartsManual.com and try a Nissan dealer up in Canada, but the US dealers show these as NLA.

[siteunseen]

I lost my dash lights and did this to fix them. Flipping those plates over made them like new.

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