1976 300D turn signal issue

Two weeks ago my left turn signal started to act up. Sometimes the blinking rate increases, or the headlights/dash lights flicker in time with the signal, and sometimes the Fasten Seatbelts light flashes. Am I correct in thinking the turn signal relay needs to be replaced?

Thanks!

Forums

Body and Interior Specific Aid

Chassis Model Number

W115

Suggestions

I would start by cleaning ALL your light bulb holders, bulb ends, and wiring plugs both front and rear - then use dielectric grease to increase conductivity at all bulb and plug contact points. If no improvement then replace the flasher. If you are still having trouble after performing those tasks, then the problem may be in the turn signal switch/lever assembly. Report back your findings. Thanks, Kent

Help! New symptom

I haven't had a chance to do all the cleaning/greasing yet, but am wondering if a new problem I'm having is related:

I've had to get 2 jumps in 2 days. Thursday I left the dome light on all day (stupid!) and got a jump in the evening. Friday morning my car started really hard & slow, I drove across town to breakfast, and when I came out from eating all I got were a few clicks. Took the battery (Duralast 850 cold cranking amps) up to Autozone and had it charged. Dropped it in and it started up just fine. Started fine again four hours later. But this morning - not even a click, and a zero reading on the voltmeter.

I'm wondering if this turn signal issue could be draining my battery, or if I'm looking at a new problem. Any advice would be greatly appreciated!

Could be two problems

Get your alternator output tested first. You may have a worn-out voltage regulator that is not connected to your other problem. Also check that your alternator belt is not slipping. If you confirm your alternator is working properly and the battery problem persists - then go after source of battery drain. If you are not familiar with how to do this you may need the help of an auto electrician (who does not need to be a Mercedes mechanic).

Battery and alternator problems

I own six older Mercedes and I have owned them long enough to have learned a few things about the electrical system.

Number one, once a battery has been drained to the point that it will not turn the motor over, it will never be the same. Lead acid batteries have a life expectancy and completely discharging them damages them. Once this happens with the extra load a diesel engine places on a battery it will die sooner. (the extra load is not just the starter, it is heating up the glow plugs)

Number two, take good care of your glow plugs and they will take good care of your battery. Kent sells replacement glow plugs and a reamer to clean out the glow plug holes. If your glow plugs are working right your diesel will consistently kick over in a couple of cranks. Installing new glow plugs is easier than changing spark plugs and using the reamer adds just a few minutes to each hole.

Number three, Mercedes work alternators hard, and diesels are even worse, I think due to the shaking. The bearings go on the alternator and there is nothing you can do but replace the alternator. If you have a stethoscope with a stiff hose on it you listen to the sound of the alternator. Bad bearings make an ugly grinding sound that is unmistakable. If you do it yourself or go to someone other than a Mercedes dealer make sure that the belt tensioning device is set up properly. Excessive tightness on the belts can lead to early destruction of bearings and belts.

One problem I had with one of my diesels was a bad glow plug relay box. I lost the charge in an almost new battery three times and almost changed the alternator before I discovered the glow plug relay was not turning off after it had heated up the glow plugs. Not a common problem but one that can be baffling when everything else is working right.

Good luck,
Michael

crazy blinker

I don't know why the headlights would blink but just a thought here... my third brakelight is out (one in the back window) and when i step on the brake for the 1st time after starting the car the dash light comes on telling me i have a light out no big deal but here is where our issues are similar when the right signal is turned on it blinks like mad the left doesn't it's fine! Having one bulb out sends a differant one into a blinking fit. So i ask do you possibly have another bulb out elesewhere (lisence plate, brake ect. something you wouldn't notice but cops would) maybe this can help