Help debugging a failing left turn signal?

cali-navion-23j

New member
Hi everyone! Long time reader, first time poster :)

I'm wondering if anyone can help me on how to debug the left turn signal on my T1N. It completely stopped working (no lights blink, the dashboard indicator doesn't blink, and the clicking sound fires double speed), but it's not the bulbs because when I turn on the hazards, ALL of them work just fine.

So i went searching for a fuse to replace and after a TON of searching I finally found fuses labeled "EDW, Left Turn Signal" and "EDW, Right Turn Signal" under the drivers seat (pictures attached). They're in the A5 and A6 position, which I couldn't find until I removed the driver's seat entirely and saw the A block tucked right up against the wall nearest the gas pedal.

But no amount of fuse swapping got it that left turn signal to change it's behavior! Eventually I just removed all 9 of the A-block fuses to see if I could recreate the behavior on the **right** turn signal - but even with all of those fuses removed the right turn signal still worked just fine...

I can't tell if I have the wrong fuse (maybe it's mislabeled?), or maybe the "EDW" fuse just isn't what I think it is? But that's the only fuse that had anything to do with turn signals at all!

Any ideas? Thanks so much in advance for any knowledge shared!

All pictures here: https://imgur.com/a/s5ujcFs
 

NelsonSprinter

Former Nelson BC Sprinter
A5, A6 look like the relays for the turn signals.
There might be another fuse in the steering column fuse box
 

VinceP

2005 158" High Roof Pass.
I had a similar issue with my flashers, and it turned out it was a problem with the Fuse Box #1 under the steering. Common problem that has been discussed here in some other threads.

I replaced the entire fuse box and relays (they come with the fuse box) for a relatively decent price, i think it was around 150$ US$. No issues since then
 

Aqua Puttana

Poly - Thread Finder
The EDW relays relate to the remote door lock verification lights flashing. They are not used during normal driving turn signal operation.

I would be looking to a side specific problem with the FB#1 as mentioned, or possibly the MFS unit circuits.

There are schematic diagrams in the 8w section of the Service Manual.

:cheers: vic
 

autostaretx

Erratic Member

Cheyenne

UK 2004 T1N 313CDi
My first thing to check would be the relay at the bottom of Fuse Box #1 on the steering column, see picture below:

Fuse Block Stg Column.jpg

Try un-plugging and re-plugging it first then swap for maybe the wiper relay if that doesn't work.

Keith.
 

Aqua Puttana

Poly - Thread Finder
My first thing to check would be the relay at the bottom of Fuse Box #1 on the steering column, see picture below:

...
Worth trying because easy enough to do, but that relay and the FB#1 flasher module is common to right/left turn signal and the emergency flashers. With only the left side being symptomatic the problem(s) are more likely somewhere else in the circuit(s).

:2cents: vic
 

Aqua Puttana

Poly - Thread Finder
... and the wheelbase is one of the selection items.

--dick
Possibly. There is real world experience which supports that WB may not matter.

Some additional information about the MFS styles can be gleaned from some other threads.

Basically it appears that "P" type Parking lamp side select and the non-"P" (no parking lamp side select) can be substituted without any overall operation issues other than adding or deleting the parking side select option.

It also appears that the MFS that is listed for shorter wheel bases can be installed on the 158" WB models.

Double check to verify that my comments are correct before diving in.

Column Switches/Controls
https://sprinter-source.com/forum/showthread.php?p=816013#post816013

low gone out while intermittent is flakey
https://sprinter-source.com/forum/showthread.php?t=73826

:cheers: vic
:2cents: vic
 
I had the same problem with the left side turn signal.
My problem was in the MFS MULTI FUNCTION SWITCH
REPLACED that and was fixed. Hope this helps
 

cali-navion-23j

New member
Thanks so much everyone!

My first thing to check would be the relay at the bottom of Fuse Box #1 on the steering column, see picture below:

View attachment 122682

Try un-plugging and re-plugging it first then swap for maybe the wiper relay if that doesn't work.

Keith.
Good thought but no dice, I swapped it around with the wiper relay and no change in behavior.

I had the same problem with the left side turn signal.
My problem was in the MFS MULTI FUNCTION SWITCH
REPLACED that and was fixed. Hope this helps
Will try this next!
 

balley603

New member
I have the same issue and wondered if there was any resolution that you can share? Only right side turn and 4-way turn on as normal, all (left and right) lights work when locking/unlocking the doors. Left side nothing, no exterior lights and no turn indicator on the dash light up, only a rapid clicking like a bulb is out. Checked the all the fuses, swapped relays under the seat (1 and 2), swapped relay in fuse panel in steering column with no change. Frustrating to be on a two week trip and have this fail with no typical fix available. Any help appreciated.
 

Patrick of M

2005 T1N 2500 (NA spec)
I dealt with something similar recently.
Here:

Can't say this is definitely your problem, mine was worse only half the hazards worked as well....common issue is the FB, pushing and shoving the FB might help, you could try that first.
 

balley603

New member
I dealt with something similar recently.
Here:

Can't say this is definitely your problem, mine was worse only half the hazards worked as well....common issue is the FB, pushing and shoving the FB might help, you could try that first.
So mine was working fine the beginning of a 2 week trip. Then the left turn lights stopped coming on but the right works as it should. 4-way flashers only lights up the right side but the remote door lock will flash both right and left lights. tried swapping the relays under the seat - no change. All the fuses are good both under the seat and steering column. Pulled the 4-way flasher out and everything goes out as it should. So for me the only thing not working is the left turn lights will not come on to flash either with the turn signal or 4-way flasher. I'm another 10 days before returning home and would like to repair it myself since any local shops in my current location can't get me in for a few days and I'm on the road each day.
 

Patrick of M

2005 T1N 2500 (NA spec)
Short of trying to do the very fussy possibly fail prone repair that is documented somewhere on this site, replacement of the MFS could do it, as your symptoms are very much the same as mine (btw can you fool the 4 ways to light all corners by activating the R turn stalk while turning on 4 ways? If f yes I would feel comfortable saying definitely MFS)
Pulling the MFS you will need a T25 but not a socket one a straight shaft 3” long (2”might do) to remove the airbag assembly.

REMEMBER:

BATTERY DISCONNECTED 10 MINUTES PRIOR TO AIR BAG REMOVAL!

10mm Allen key for center steering bolt.

Wheels pointed straight ahead, steering wheel straight, mark position of steering wheel relative to shaft, prior to pulling steering wheel.

I just did this so it’s fresh, there’s is a write up somewhere on site.
 
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Aqua Puttana

Poly - Thread Finder
Short of trying to do the very fussy possibly fail prone repair that is documented somewhere on this site, replacement of the MFS could do it, as your symptoms are very much the same as mine ...
All 4 corners flashing when the remote locks are activated points toward the MFS. The security visual feedback relays are independent from the MFS flasher circuit. It should be a SOP test for turn signal problems if the Sprinter is equipped with remote locks.

:2cents: vic
 

jrod5150

Active member
Short of trying to do the very fussy possibly fail prone repair that is documented somewhere on this site, replacement of the MFS could do it, as your symptoms are very much the same as mine (btw can you fool the 4 ways to light all corners by activating the R turn stalk while turning on 4 ways? If f yes I would feel comfortable saying definitely MFS)
Pulling the MFS you will need a T25 but not a socket one a straight shaft 3” long (2”might do) to remove the airbag assembly.

REMEMBER:

BATTERY DISCONNECTED 10 MINUTES PRIOR TO AIR BAG REMOVAL!

10mm Allen key for center steering bolt.

Wheels pointed straight ahead, steering wheel straight, mark position of steering wheel relative to shaft, prior to pulling steering wheel.

I just did this so it’s fresh, there’s is a write up somewhere on site.
its not the position of the steering wheel you need to worry about it only goes on one way. You just need to make sure the clockspring doesnt turn and gets a 360 in the wrong direction.
 

balley603

New member
All I can locate is a MFS with Parking Light Control feature. Will this unit work in a non-Parking Light Controled configuration? Weird that all the local suppliers only stock the switch with the added parking light control, I would think its the most popular since the other is special order.
 

Patrick of M

2005 T1N 2500 (NA spec)
I think that they interchange, surprised you don’t have the parking light feature, it is on the stalk but you turn the opposite way than for the main lights.
 

Aqua Puttana

Poly - Thread Finder
All I can locate is a MFS with Parking Light Control feature. Will this unit work in a non-Parking Light Controled configuration? ...
Yes. That option is all within the MFS.

vic
 

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