I have researched this forum and gone through all turn signal threads...no help with my symptom...

My left turn signal has been behaving erratically for some time...sometimes it works, sometimes doesn't .... I have checked and replaced the relay/bulbs and all that...no help..the erratic behavior continues..

Now, finally, since last 2 days, it has completely stopped working..I swaped left/right turn signal relays and bulbs...and have ruled out the bulb and the relays as a problem.

When I flick the left turn signal, with the fusebox cover open, I hear the left turn signal relay ticking at twice the normal frequency...the relay ticks fine, but no lights..swap the right turn signal relay with the left and the right turn signal relay too does the same thing...put it back for the right side, and the relay works fine and so the relay is not the problem..

Does anyone know, what module times and drives the turn signal relays? It almost seems like whatever is controlling the timing of the relay ticks is malfunctioning..

 

Does not sound like a module to me since the relay is working. Can't be the switch for the same reason. Could very well be a bad ground since it seems to be behaving like a bulb problem and you have confirmed the bulbs are OK.

 

I was just reading on another forum...what I am experiencing is 'relay chatter' and is very likely caused by a 'grounding problem' or 'weak current' to the relay...the weak current causes a weak electromagnetic field, not enough to hold the relay in place and that causes it to chatter back and forth..

Hmm...I think, going to a pro might be the best thing to do....because, next step is very likely to dig in the wiring diagram...to find the fault...

 

As I was fiddling some more, I accidently happened to put my hand on some fuses in the fuse box and the relay stopped chattering - the signal lights came on briefly.

I immediately inspected the fuses that my hand had pressed on, and sure enough fuse F2 was one of them and it is for the left turn signal.

I re-inserted the fuse and pressed hard. The turn signal lights now come on. A little thump on the fuse box knocked the fuse loose again. Tomorrow, I will certainly replace the fuse, but it seems the fuse panel is aging out.

And now, that an aging fuse panel is a confirmed diagnosis for this problem, another weird problem that has been nagging me for a while too could be related to the fuse panel..the car sometimes just refuses to start with dead silence...

https://mbworld.org/forums/m-class-w163/209719-ml320-will-occassionaly-not-start.html

Turn on the key and the lights on the dash come on, but otherwise dead silence in the engine bay...on the next few attempts it hesitates to start (think of 'weak current' to the starter like symptom)..and after a few tries, it suddenly starts...shut it down and it may or may not repeat the dead silence/hesitation sequence...sometimes it repeats sometime doesn't. I couldn't corelate it to cold/warm engine either - its pure just random and erratic as much as the turn signal issue was..the mechanic has already ruled out the CPS, ignition key hole, FOB and the starter for this....he too is perplexed with the truck's weird behavior...I won't be now surprised if the problem goes away from tomorrow and I find a ignition related fuse somewhere around fuse F2...And if it reoccurs I know what to look for now...possible relay chatter in the fusebox...and possibly a lose fuse somewhere..

Its about $250 to purchase a new fuse panel inclusive of a brand new set of relays & fuses. Might not be a bad idea for me to consider replacing it entirely..since I intend to keep the truck for at least another 5-7 years..

Sosh, your diagnosis was right though, it couldn't be the module, & a loose fuse will very likely result in weak current, and thus the relay chatter.

 

That is not surprising.

Fuse contact corrosion is a common occurance when cars age. Some folks remove the fuses and reinsert them a couple of times every 10 years or so to prevent electrical failures in older cars... This scratches off the corrosion on the contact.

The starting problem may also be fuse related. I would look for any fuse or relay powering the starting circuits, for example F6 (terminal 15). Good luck, and thanks for the detailed description!

Some related info is on this page:

http://www.whnet.com/4x4/shoptalk.html

 

Turn signal problem is gone once and for all...

Re-inserted ignitiion/starter solenoid related relay....starting problem hasn't recorred since then...

Sosh & Wolfgang, thanks for your input..

 

When you have a few minutes you may want to remove and replace all fuses and spray a little CRC on the contacts as you do so. May prevent a future problem. This is common in high corrosive enviornments like near the coat, etc.