Fog light switch replacement help

mything2

Member
I have a 2007 Airstream Interstate and I believe I have a bad fog light switch but cannot see a way to remove and replace the switch without first taking apart the dash components.
To back up a bit, my conclusion about a bad switch is due to no power on the circuit feed to the fog lights. I’ve checked the fuse panel and it’s OK so I’m ASSuming it’s the switch.

Any ideas and/or procedures appreciated.

Dan
 

Cheyenne

UK 2004 T1N 313CDi
Dan,

The fog light switch will almost certainly be the standard MB fit so you would do better asking on the T1N sub forum (I note your 2007 AI is actually on a 2006 chassis).

Keith.
 

autostaretx

Erratic Member
The fog lamp switch on a T1N feeds a relay. If the relay coil has failed, you'd also see no fog light action.

The switch is a SPST (single pole, single throw) non-momentary (i.e. when switched ON, it stays on), with a light.

In the 2006 service manual, the switch is shown on page 8w-50-9, and the relay and lamps on page 8w-50-10
The switch/relay and the lamps have separate fuses.

--dick
 

mything2

Member
The fog lamp switch on a T1N feeds a relay. If the relay coil has failed, you'd also see no fog light action.

The switch is a SPST (single pole, single throw) non-momentary (i.e. when switched ON, it stays on), with a light.

In the 2006 service manual, the switch is shown on page 8w-50-9, and the relay and lamps on page 8w-50-10
The switch/relay and the lamps have separate fuses.

--dick
Dick- TUVM for your reply. Although my RV is a 2006 model year Sprinter, it’s a 2007 Airstream buildout and the fog lights were added during the RV conversion so there’s another fuse location...that’s what I’m trying to locate....it’s somewhere in the engine bay I’m told by a local Sprinter mechanic. Any idea how I can locate it?
Dan
 

PilotAndCorgi

New member
im having the same issue. I've checked the fuses. wondering what relay to try and replace. or another fuse location. did you ever figure out?
Thank you
 

ECU

Well-known member
The factory switch goes to ground. It triggers a relay. So it is more likely the relay that is under the seat.
You can get to the switch, barely. Pull out the storage bin below the switch and you can just about reach the switch from the back. Like all the factory switches, it has releases at the top/bottom of the switch to pop it out.
 

PilotAndCorgi

New member
The factory switch goes to ground. It triggers a relay. So it is more likely the relay that is under the seat.
You can get to the switch, barely. Pull out the storage bin below the switch and you can just about reach the switch from the back. Like all the factory switches, it has releases at the top/bottom of the switch to pop it out.
thank you.
I tried changing around all the small relays under the seat without any luck. the fog lights get 12v when both are unplugged. if I plug one or both in they get about 1-2 volts. like they don't work under load. I changed the bulbs even though they looked okay. don't see where the housing might be grounding or something. do you know if its a larger relay or more specific location. my diagram on the chair isn't very helpful.

on another light issue.
my lights come on after I start the van (new issue after messing around) not the running lights. its like I turned the lights on with the switch on the wheel. with the key on (not the engine) headlights/ tail lights work normal. start engine. some relay switches under seat and all the lights are on regardless of where I put the switch/ arm off wheel. I still have to turn the lights on if I want to use the brights....

thoughts on either issue please?
thank you!
 

ECU

Well-known member
I may have read this wrong at first, these are aftermarket fogs? Are you sure the lights housing are grounded? Possible wire not big enough to handle the load? probably a 12 gauge wire.
As for the other. That is your Daylight Running Lights. Basically the low beams and all marking lights on when the engine runs. You'll notice that the dash lights and high beams are not on in this mode. To get high beams, you need to actually turn the lights on first.
There are three fuses that control this 'feature.' One runs the parking/marker lights and can't be turned off. If you pull that fuse, you lose other things you need. The other two are each headlight. Pulling these simply doesn't let them turn on automatically.
 

PilotAndCorgi

New member
I may have read this wrong at first, these are aftermarket fogs? Are you sure the lights housing are grounded? Possible wire not big enough to handle the load? probably a 12 gauge wire.
As for the other. That is your Daylight Running Lights. Basically the low beams and all marking lights on when the engine runs. You'll notice that the dash lights and high beams are not on in this mode. To get high beams, you need to actually turn the lights on first.
There are three fuses that control this 'feature.' One runs the parking/marker lights and can't be turned off. If you pull that fuse, you lose other things you need. The other two are each headlight. Pulling these simply doesn't let them turn on automatically.
they are the stock fog lights. At least run off the stock switch maybe changed a little by airstream if they put a body kit on there.

ive changed a few fuses. You’re saying not just the headlights are supposed to be daytime running lights but all the exterior lights are? Even the dash seams to dim. You do still have to turn the lights on to get the AC buttons etc to illuminate.
 

ECU

Well-known member
Are the fog lights in the headlight assembly? Factory fogs are the zone directly below the low beams.

The 'dash' is different than the lights in all the switches and heater. Those only come on when YOU turn the headlights on.
Yes everything is DRL.
 

PilotAndCorgi

New member
Are the fog lights in the headlight assembly? Factory fogs are the zone directly below the low beams.

The 'dash' is different than the lights in all the switches and heater. Those only come on when YOU turn the headlights on.
Yes everything is DRL.
okay I guess the DRL makes sense now. I guess they weren't working before and I changed a couple fuses while trying to fix the fog lights and now they all come on automatically after engine start. before id turn them on manually with the stick. the headlights were always on before while engine on so thats why I thought all being on was wrong.

Okay, yeah the fog lights are their own assembly. I'm guessing added by airstream. but ran off the stock switch, only verified the switch does anything by the change in voltage at the light when ON/OFF.

IMG_1097.PNG
 

ECU

Well-known member
Those are aftermarket. You need to check the grounding. The mounting is into plastic, no body grounding.
There is a grounding wire from the light to the chassis. You could easily get a wire and attach it to ground and to the light to test this.
 

PilotAndCorgi

New member
It ended up being an aftermarket relay hanging by the battery. (The fog lights were installed by airstream which was news to me. As most things are..)
I overlooked it thinking it was too big for fog lights.
ordered a cheaper one off Amazon.
P/N on the side comes up as a blower motor relay for a GM and such.
Received it today. Fixed my fog lights. Another little thing fixed off my list.

Thank you for the help.
I’ve been doing a lot of small things to the van. Still more to go. Willing to share my experience and lack there of.
 

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