I don’t drive at night very often, so on this last trip I was surprised to see (actually not see) that my instrument panel lights weren’t working.
When we stopped for the night, I checked the usual stuff. The fuse was good and was getting 12 volts in and out. I looked at the diagram for switch, I could jumper across the switch and the lights came on, so I knew I had a problem in the switch. When I removed the switch, there was something rattling inside. When I tore it apart, I found the power transistor had gotten so hot, it unsoldered itself and was laying in the bottom of the switch.
I found a replacement switch on Amazon for $51. However, before buying it, I’ll see if I can repair the original.
The switch disassembles fairly easily, and the circuit board pops off. The instrument lights are Pulse Width Modulated (PWM) to control brightness by turning the power transistor on/off real fast. I was taking a chance that the PWM oscillator IC circuit was OK and the only problem was the MOSFET power transistor had blown. I figured if the new transistor didn’t fix it, I’ll buy a new switch assembly and only be out the cost of the transistor.
TRANSISTOR REPLACEMENT
I researched the original transistor, MTP50N06V. It was obsolete but there was a replacement from NTE available for $7. I researched a little more and found another, less expensive replacement, RFP30N06LE. These were substantially cheaper, and I could use them on some other projects I’m working on. There was one difference. The original was rated at 125 watts, the replacement can only handle 95 watts. OK not a big deal. I can replace the original lights with LEDs and that will bring the current draw down substantially.
I replaced all the 194 light bulbs in the instrument panel with LEDs from Amazon. I checked the current in the instrument light circuit. The original lights were just under 2 amps. With the LEDs, it was less than half, 0.6 amps.
I soldered the new transistor in the circuit and was pleased that it worked just fine and didn’t seem to be producing any heat. I won’t be driving the Southwind for a couple months, but I’ll re-check the lights later tonight when it gets dark to make sure they are OK.
PS – If you want one of these transistors but don’t want to buy 10 of them, send me a SASE and $1. I’ll put one in the mail to you.
Quick question about light bulb replacements. Are they brighter? And where can I find them.
They seem about the same brightness. The ones I used seem more of a bluish white. Got them on Amazon, there is a link in the article.
thank you
Hello! I have a1999 F53 Damon and no taillights or dashboard lights. What is the fuse box fuse number location? Is it in the box inside under the dashboard or under the hood fuse box?
Check the connector on the back of the headlight switch. These have a habit of falling off.
Looks like tail lights are on the fuse box above the radiator and the instrument lights are inside under the dash.
Here is a link to the F53 chassis, fuses are on page 39
http://1999southwind.com/DOWNLOAD/F53_1999_Owners_Manual.pdf
Thank you Thank you Thank you! for the many helpful fixes you have written about over the years. I have used many! And once again, my taillights are working now thanks to your advice. Loose connection at the switch is all it was!
my 1997 southwind has no dash lights..i read your suggested fix…i want to replace the dashlight bulbs…are they all the same size and what is there part number and are there really 194…lol
If I remember, All the illumination lights were 194s, But I seem to recall there were a couple other bulbs for idiot lights that were smaller.
lol i miss read it the part number was 194 about how many should i buy..rhank you
Hello, just came across your thread and wanted to ask…. I have a 2000 ford f53 motorhome chassis where I can’t get the dome lights to work. It’s has the same switch as you. I’ve tested everything I know and even replaced the switch but nothing. I do get voltage at the lights when I ground it with my meter on both legs. Any thoughts on what it could be would be very much appreciated.
I think the dome lights are also controlled by one of the toggle switches beside the steering wheel.. i.e. three switches need to be ON, The dimmer light switch, the switch on the light fixture, and the toggle switch beside the steering wheel.
Thanks for the reply…. I only have one switch that controls the dome light. That’s the one on the head lamp switch. It also controls the dimmer on the dash. In my case there are no on/off switches on the dome lights. Starting to wonder if the GEM is the issue? Any other thoughts? Remember this is a motorhome chassis.
Thanks for the reply. In my case the only on/off switch is the headlight dimmer switch. I’m beginning to think it might be the gem electronic module? Any other thoughts?