turn signals failing

surlyoldbill

Well-known member
I noticed the other day that my turn signal was just stuck on, no flashing, it was both sides and all lights are working. When I restarted after a stop, they were working again. I noticed this three times in the last few days. I haven't checked to see if the emergency lights still flash when my turn signals will not.

Is this a known issue, and if so what is the diagnosis?
I'll play with the relay tomorrow to see if it's not seated well.
 

Amboman

New member
The hazard flashers have a direct link to the turn signals and the turn signal relay located on the fuse board.
 

220629

Well-known member
I believe that people are confusing the Turn Signal "B" Relay with the flasher module. The relay is mounted on the bottom of Fuse Block #1 and is a removable plugin style relay. The flasher module is integral with the Fuse Block #1.

Refer to the info below and the text in the previous diagrams I posted.

Relay position #1 here.

012FuseBlock#1wNotes.jpg

vic
 

surlyoldbill

Well-known member
Yeah, I probably just need a flasher module. You say that's integral to the fuse block, meaning that it is not removable/replaceable?
 

220629

Well-known member
This information is supposedly from an 05 manual, but it showed a mechanical low pressure fuel pump?

This discusses the turn signal relay. Page 8L-24

TURN SIGNAL RELAY
REMOVAL

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, DRIVER AIRBAG, PASSENGER
AIRBAG, SEAT BELT TENSIONER, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT
AND ISOLATE THE BATTERY NEGATIVE
(GROUND) CABLE, THEN WAIT TWO MINUTES FOR
THE SYSTEM CAPACITOR TO DISCHARGE BEFORE
PERFORMING FURTHER DIAGNOSIS OR SERVICE.
THIS IS THE ONLY SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.

(1) Disconnect and isolate the battery negative
cable.
(2) Remove the fuse access panel from the steering
column opening cover below the steering column on
the instrument panel.
(3) Reach through and below the inboard side of
the fuse access opening to access the turn signal
relay (Fig. 47).
(4) Remove the turn signal relay by grasping it
firmly, releasing the latches and pulling it straight
down from the receptacle on the bottom of the fuse
block.

INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.

(1) Position the turn signal relay to the receptacle
on the bottom of the fuse block (Fig. 47).
(2) Align the turn signal relay terminals with the
terminal cavities in the fuse block receptacle.
(3) Push firmly and evenly on the top of the turn
signal relay until the terminals are fully seated in
the terminal cavities in the receptacle of the fuse
block and both latches are fully engaged.
(4) Reinstall the fuse access panel onto the steering
column opening cover below the steering column
on the instrument panel.
(5) Reconnect the battery negative cable.
******************************************************


This discusses the control module. Page 8R-3
(It is the part labeled "Made in Italy" on page 12 above.

² Wiper, Turn Signals, Engine Start Control
Module - The wiper, turn signals and engine start
control module is integral to the fuse block located
underneath the steering column. The fuse block is
concealed behind the fuse access panel and the steering
column opening panel, where it is secured with
screws to the steering column. The wiper, turn signals
and engine start control module contains the
intermittent wipe logic circuitry, which includes
active electronic elements that allow it to provide the
intermittent wipe delay and the wipe-after-wash features
of the intermittent wipe system based upon
numerous hard wired inputs
, then provides the
proper programmed hard wired control output to
operate the wiper motor through the wiper relay.
Hard wired circuitry connects the wiper and
washer system components to the electrical system of
the vehicle. These hard wired circuits are integral to
several wire harnesses, which are routed throughout
the vehicle and retained by many different methods.
These circuits may be connected to each other, to the
vehicle electrical system and to the wiper and washer
system components through the use of a combination
of soldered splices, splice block connectors, and many
different types of wire harness terminal connectors
and insulators. Refer to the appropriate wiring information.
The wiring information includes wiring diagrams,
proper wire and connector repair procedures,
further details on wire harness routing and retention,
as well as pin-out and location views for the
various wire harness connectors, splices and grounds.
*****************************

If the module is replaceable it would require complete removal of the Fuse Block #1.

If the prices mentioned in this thread are accurate then it would be a cheap module. That is unlike mother Mercedes for pricing. :idunno:

vic

P.S. - "Hard wired inputs" may be as opposed to CAN bus communication, but I'm quite certain the turn signal, et al. module is soldered on to the board.
 
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surlyoldbill

Well-known member
Ok, so while they aren't working, I wiggled the relay at the bottom of the fuse block and they worked again. I'll get upside down and remove the relay, clean the contacts and re-install. If it's just that little relay that is bad, I can see it being $20 instead of $100. The $100 must be for a new timer module.
 

CruisnDiesel

New member
I have had a similar turn signal problem with my 2004 T1N. I replaced the relay (~$15 non MB part). It worked for a day or two then became intermittent. I noticed over time that if I moved the relay they would start working again. Also if I pushed against the plastic fuseholder cover under the steering column I could get them working. Sounds like I may have a loose wire in there somewhere.
 

surlyoldbill

Well-known member
Yeah, I should do this fuse block operation so I don't get surprised 50 miles from the nearest paved road this summer.
 

EZoilburner

03 2500 158wb HR
A little late but yes, it is a MB relay I purchased from the dodge dealer since the MB dealer is about 30 miles away. I removed the fuse block under the steering wheel and I have to admit I was intimidated when I started taking it apart but it is really simple, I used a needle nose plier to re-tighten the pins/connectors cleaned them all as well then put it all back together and all is well for the last month.
 

chris118

Member
For what it's worth, when my signals stopped working, I just pulled the relay at the very bottom of the fuse block below the steering wheel, cleaned the contacts and put the old one back in.

Every 3-4 months, or if I'm driving on washboarded dirt roads, I it'll go out and I just wiggle the relay and it works again...

Been doing this for 4 years
 

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