What would cause dash lights to dim and brighten by them selves (1 Viewer)

[fj40z]

My dash lights have recently just started dimming and brightening totally on their own. It happens very intermittent and sometimes they stay either bright or dim for a long time then they might change several times in a minute. Throttle position doesn't change anything nor does bumps in the road. I just recently replaced the radiator and while I was in there replaced the belts as well. I'm wondering if I spilled some antifreeze on the alternator when removing the upper hose and that's causing the problem. It happened several times on my 40 minute commute to work this morning. Also should mention the dimmer knob doesn't seem to be working at all.

 

[jdayment]

Poor ground or possible that the alternator or battery are beginning to go out. When the alternator goes it will usually light up the dashboard though. I would check your grounds first.

 

[jwilliams]

I was going to suggest alternator as well.

 

[jfz80]

I got a used alternator if you want to try it before calling up your denso man!

We should look at grounds as well and get the firewall one to metal vs the plastic harness clamp.

Second guess would be something to do with the dimmer. Wonder if that switch/reostat (?) is broke but can make intermittent changes somehow

 

[RiFF RaFF]

I got a used alternator if you want to try it before calling up your denso man!

We should look at grounds as well and get the firewall one to metal vs the plastic harness clamp.

Second guess would be something to do with the dimmer. Wonder if that switch/reostat (?) is broke but can make intermittent changes somehow

The dimmer rheostat was my first idea also - could be a loose / corroded connection.

 

[fj40z]

Good call on the rheostat connection. Now back to searching

 

[izzyandsue]

Failed attempted alien anduction too can cause that.

 

[stevezero]

Spirits...hopefully not the evil kind.

Double check your grounds, and then check the rheostat. Intermittent ground could cause the fluctuation

 

[george_tlc]

80 dash bulbs get +12V from battery/fuse.

The rheostat varies the ground side voltage of all the bulbs. If 0V then bulbs see the full 12V across them.

Anyhow, EWD for the 96 should be close enough. Check all connections to the rheostat and measure some voltages as you adjust it.


cheers,
george.

 

[blkprj80]

Also should mention the dimmer knob doesn't seem to be working at all.

Start there. Once you have the switch unplugged, you can measure ground and power at the plug.