Dash gauge lights

[bryanaltier]

Good morning, after a trip which we did not get home until after dark I noticed that all the dash gauge lights were out. Headlights and all clearance lights were working. Thought that his must be the dimmer switch so purchased one from Dan Hartley and that did not solve the problem.

As said all headlights work, high and low. Daytime running lights work. Have power to the headlight switch showing 24 volts and very low voltage to dimmer switch, around 7 volts.

The more I looked the more confused I got as all of the dash gauges have only 3 wires running to them, all in series. All gauges are working.

The gauge lights working list time I drove after dark and I have made no changes to any wiring. Checked fuses and all good. Any ideas?……

[Randy Dupree]

Headlights are 24 v?

[bryanaltier]

Randy, that’s the voltage I am getting at the switch. I think the bulbs are 12 but not sure where there is a transformer for the voltage drop. In checking the switch I had the meter on 20 V and kept getting an error, bumped to up and got the 24 volt reading. ?……

[Randy Dupree]

I was surprised they would have 24 to the switch and 12 to the lights.
But 7v to the gauges is odd.
I am assuming the bulbs in the gauges are 12v?

[Randy Dupree]

Rereading your post,24 to the headlight switch but 7v coming out to the gauges?
That would indicate a bad headlight switch?

[bryanaltier]

That’s what I thought bad switch but voltage coming in and out matches. The thing that also has me scratching my head is the wiring to the gauges. All only have 3 wires.. the same 3 wires jumping from one to the other. No visible light connections. How do these work the same wires running out of the the dash to the first gauge and then jumping to each of the others. Discovered this attempting to get voltage on the light connections.

Will do some further checking this afternoon

[Randy Dupree]

So does the dash lights have their own relay that the headlight switch makes or breaks?
I can't see the gauge people making 24v lights for the gauges.
So i would be looking for a rely,switched by the headlight switch that sends 12v to the dimmer and then on to the gauges.
Does that make sense?

[Shawnthegrasshopper]

Originally Posted by bryanaltier

Good morning, after a trip which we did not get home until after dark I noticed that all the dash gauge lights were out. Headlights and all clearance lights were working. Thought that his must be the dimmer switch so purchased one from Dan Hartley and that did not solve the problem.

As said all headlights work, high and low. Daytime running lights work. Have power to the headlight switch showing 24 volts and very low voltage to dimmer switch, around 7 volts.

The more I looked the more confused I got as all of the dash gauges have only 3 wires running to them, all in series. All gauges are working.

The gauge lights working list time I drove after dark and I have made no changes to any wiring. Checked fuses and all good. Any ideas?……

Brian
I had a Similar situation on my M380, I know it’s Not a m450 and 24volt.

My Headlights, Running light and Daytimes All work While parked, If I drove down the Road the Marker Lights and Dash would Go on and off unless I Dimmed the Dash lights.

I then tried Dimming the Dash lights and the Problem Stopped, Dimmer Switch. Right?
No as soon as I Slid up to brighten Dash lights same issue!!!

I checked Fuses/Breakers and Relays, None were Tripped!

But Some Resettable Fuses were Hot/Warm to the Touch, I pulled out and Swapped out with other Breakers and Problem Solved!

Hope this is your Issue!

[bryanaltier]

Randy you are right when I turn in the headlights I can hear a relay and the headlights come on which make since. I am attempting to locate under the dash. Also hear relay for park lights.

I have checked breakers that I know of and found none tripped or hot.

[bryanaltier]

After checking the voltages and switches I think Randy is correct and the headlight switch itself may be bad. Hopefully I can locate one and get it here before Christmas as we plan to leave right after the holiday. Will advise when I get it. Thanks