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les.warden · 11-17-2016, 06:12 PM

2017 Phaeton 40QBH. Turn headlights on and the dash lights will go off and come back on intermittently. If I use the light dimmer, rather than dimming, they will go off. Then I use the dimmer to brighten them back up, they go from off to on, but then back to flickering. Here's a kicker...my friend just drove his new 2016 Phaeton from LA, and it did the exact same thing. We're thinking his was built end of 2016 season and mine was beginning of 2017 season. Mine was Aug of 2016 (yet called a 2017). I'm scheduled back at the dealer in MO on 11/30/16 to winterize and tweek minor issues so far and I will ask at that time. Thought I'd throw this out to the group and see what kind of feedback I get. Almost have 1,000 miles on it to date and loving it!

billdreamlv · 11-17-2016, 10:04 PM

Quote:

Originally Posted by les.warden

2017 Phaeton 40QBH. Turn headlights on and the dash lights will go off and come back on intermittently. If I use the light dimmer, rather than dimming, they will go off. Then I use the dimmer to brighten them back up, they go from off to on, but then back to flickering. Here's a kicker...my friend just drove his new 2016 Phaeton from LA, and it did the exact same thing. We're thinking his was built end of 2016 season and mine was beginning of 2017 season. Mine was Aug of 2016 (yet called a 2017). I'm scheduled back at the dealer in MO on 11/30/16 to winterize and tweek minor issues so far and I will ask at that time. Thought I'd throw this out to the group and see what kind of feedback I get. Almost have 1,000 miles on it to date and loving it!

I assume that you have all LED's in your dash.
It sounds to me like the voltage to the dash lights is not high enough to forward bias the lights to an on state. LEDs will turn on once the threshold voltage is met and it sounds like the voltage is so low that they are right at threshold. My clue was when you said you turn on the headlights and the voltage drops and the dash would go completely off. Once the alternator stabilized the voltage after it recovers from the drop by turning on the lights, the dash lights come back on because they overcome the forward bias barely. Just a place to start. My guess is that they hooked up the dash lights to the incorrect voltage source, say 5 volts instead of 12 volts.

iRent2u · 11-18-2016, 03:13 AM

It is a Freightliner problem. They are aware of it. I had the same problem on my 2016 RED. Freightliner has an App 24/7 Direct. Call the 800 number and they have a person answering who has 20 plus years working on the chassis. They gave me directions on pulling a 5 amp fuse for 30 seconds and it worked. Had to do it a few times and adjusted my brightness on the dash light. Have not had a problem since.

les.warden · 11-18-2016, 04:53 AM

Thanks for the replies and guidance. This is exactly what I had hoped to find out. Whenever I start a troubleshooting process, my first step is eliminating the possibility that I'm the first one who has had the problem. Can't remember a time where I was #1, thank goodness. I'll call Freightliner and followup here with the results.

les.warden · 11-18-2016, 09:08 AM

Ok. Called FL. A known FL issue. It's some wire. Told him about the fuse thingie and FL said his issue would come back. He said you could duplicate the fuse pulling by turning the key on, go to the red battery knobs and turn them off, turn the key back off, wait 1 minute, turn the battery knobs back on, then see if the lights and dimmer work ok. I did this and they "seem" to dim/brighten ok now. Going down the road may cause it again. FL said when the fix is in, we'll be notified to get it fixed at local FL dealer. He told me my chassis was built 8/7/16. Guess time will tell.

NevadaNick · 11-19-2016, 07:51 AM

Our 16 Phaeton did it as well and finally quit doing it.

Esc Pod · 11-24-2016, 08:20 AM

Had same issue on allegro red. Freaked me out. I recycled on the key....pushed the dash lights to max....and it sorted itself.

Battery was in low voltage mode due to heater grid. Not sure if that contributed.

les.warden · 11-24-2016, 08:54 AM

The more I read about others having the same issue. The more I read about the flickering and then correcting itself...the less I think it's a wire issue and more I think it's the forward bias diode threshold issue. Guess I'll try to research FL dash issues further.

dms · 11-24-2016, 02:29 PM

Had a 2014 Phaeton with the same issue. I discovered if I adjusted the dash dimmer from bright to a little dimmer, it stopped the flickering. Mine only flickered on max bright.

NevadaNick · 11-24-2016, 02:55 PM

Mine didnt flicker on full bright, only when I tried dimming.

les.warden · 12-07-2016, 01:22 PM

Saw another write-in, in the tech section, in Roughing It Smoothly. So seems this has been going on for awhile. I'm surprised FL hasn't issued a fix for this by now. Has anyone seen the issue come back after it once "seems to correct"? I haven't driven ours enough, especially at night, to know. Maybe FL just doesn't get enough feedback on this because we're mostly parked at night. Thinking out loud here.

Rzani · 12-10-2016, 07:30 AM

I just wanted chime in here and confirm that it must be a freightliner issue because we just rented a 2017 Thor and it had this exact problem. So it isn't only Tiffins.

billdreamlv · 12-10-2016, 10:40 PM

Here is one possible cause. There are two basic LED types. One is dimmable and the other is not. To do a test we need to increase the voltage to the LEDs as high as possible. This could be done by setting any and all the dimming switches all the way to bright. This will set the maximum forward voltage to the LEDs. If they continue to flash then there is not enough voltage to the circuit board to forward bias the LEDs on. If they come on and stay on, this means that there is enough forward voltage to keep the LEDs on. If the latter is the case, then try and reduce the voltage little by little until the lights start to flash. If this is the case the culprit is to low of voltage coming out of the rheostat. If they are using dimmable LEDs, there is a special circuit that controls the dimming. I will bet you they designed the LEDs as dimmable and used a regular rheostat and lowered the voltage to dim the dash lights instead of this special dimming switch. The switch is called Pulse-Width Modulation (PWM) dimming. What this switch does is cut the time the voltage is applied to the LED but not the amount of voltage. It basically pulses at a high frequency, the LEDs on with full forward voltage instead of reducing the voltage to dim the lights. To dim the lights they reduce the frequency from the PWM. NOT THE VOLTAGE. This gives the appearance of a dimmed LED but really it is just on less time. The frequency is so fast that you can't detect the on/off (greater than 24 times a second). I will bet you Freightliner did not build in a PWM dimmer switch into the dash lights. The dash panel will take a modification to fix the board. Let me know if this works by turning on the dimmer on high as this is step one. Step two is to find out if there is a PWM in the dash circuit.

tombottcat · 12-10-2016, 11:27 PM

been having the same issues with my 2016 Thor Tuscany XTE 36MQ, will start to strobe at all different times to the point at night driving i had to put a towel over the dash, had it at freightliner and they said its not there problem and it belongs to the manufacture of the dash itself? so my truck sits in the dealers shop as we speak! kinda sucks since its -30 below and snowing, was supposed to be in Arizona now TOM AND JOANNE - nothing like life on the road