Speedo and tach lights

[driftmunky]

i was looking at this 240z and i noticed the dash lights were extremely dim. it was day time but even when i parked in an undercover area and put my hand over top of the gauges i could barely see the light shining through.

i even tried adjusting the brightness with the dimmer switch under the dash and it didn't do much.

would this be a hard thing to fix?or would i just have to change the bulbs?

[2ManyZs]

Well, if the rheostat worked (did the rest of the dash lights dim or brighten up when you tried it?) it is only a matter of pulling two dash lights out of the speedo and tach and replacing them. It can be done from under the dash if you are willing to try to become a contortionist. There should be two lights on either side of both gauges. The easy way is to turn on the lights in a dark garage and lay on your back on the floor and feel around for them. It isn't easy but it can be done.

[driftmunky]

the dimmer doesn't really work....i have to keep spinning the thing and then all of a sudden sometimes the dash lights will just go on...there is no dim or bright...just on and off...although it is quite dim...

[2ManyZs]

Sounds like the dimmer may be all or part of the problem to start with. If the contacts in the dimmer are that bad they may not be supplying the needed power to the dash lights. I'd change it first since it is easier to get to and see what works and what doesn't after that.

[EScanlon]

You could bypass it, but that might cause the wiring and bulbs to burn out or over heat.

The Dimmer Switch is a simple Rheostat Coil with a Wiper Contact. If you remember your slot cars, you'll recall the speed control. It had a single wiper contact that slid over this coil of wire. As it slid over the coil it changed the resistance in the circuit and hence the current. That's how this one works.

It may be that the coil has become corroded and will not allow contact, OR that the wiper arm has been bent up by someone reaching back there and getting it caught on a sleeve.

You CAN check the functionality of the bulbs by shorting the dimmer switch, but if the bulbs ARE burnt out, you will not think that the dimmer switch is NOT at fault when that may have been in fact what precipitated all this.

2¢