1. Home
  2. Mercedes Autos and SUVs
  3. 1987 300td with no lights... sometimes

1987 300td with no lights... sometimes

Hello from somewhere in Indiana,

We are heading back to Colorado and have fallen victim to an electrical issue. My 1st guess here is that this is a bad alternator but see what you think.

Going down the road all is fine until the "antilock" light comes on. I have little or no power to my windows or headlights. The battery is

7 months old but we have had to jump it the past week on occasion (this all seems to be intermittent). My wife lost power to the headlights last week only to have them come back on after a couple minutes and it has been fine since. We had to pull over tonight as we had no lights at all once again.

I checked battery connections and looked for any other shorts that might be obvious and have found nothing.

Any ideas?

Thanks, Jim

Reply to
yobpner
Loading thread data ...

yobpner ha scritto:

........

Ok...

Did you check alternator belt? I mean: tension and status. Something else, on the road,seems difficult to help you: you seem to miss the help of a good voltometer or electrical tester, right? Of course, check fuses and fuse box, especially the incoming wires. Sometimes the incoming wire of a harness of different services heats up, just enough to damage the contact. Sand-paper is an excellent solution... at least to temporarily overcome the problem.

Reply to
Cordy

Thanks for the thoughts... I have checked the belt tension and status. I do have an extra belt with me and I might just replace it just for good measure. I have visually checked the wires and fuses but don't see anything that stands out just yet. I am heading out to get a voltmeter this morning (the 2 in my shop just don't help me here). I will recheck all connections and see what happens...

And is there any issues with driving it during the day without real electrical power? I could possibly make it to denver by daylight and back to my mechanic.

Thanks. Jim

Reply to
yobpner

yobpner ha scritto:

By daylight and without switching engine off? ;-)

Reply to
Cordy

Take it to a place that can quickly check the system, ie battery, alternator, while u wait. I think Autozone even does it for free.

Reply to
trader4

You really need to know the voltage output to see if the alternator is bad or not. It need to push out at least 13.5V.

I would highly suspect the overvoltage relay... it has a red fuse on top of the aluminum body. Check the fuse on it... Pull the relay our and reinsert... knock on it with a screwdriver to see if that solves your problem.

Otherwise, it think it is mainly bad grounding... usually due to rust... but it can't take out the ABS and the light at the same time.

Check the grounds by the headlights... brown wires... there is a couple of places in the engine compartment where you will see all the brown wires comes to... clean out the contacts there. Check your battery ground cable... if it looks real old, then change it out too... cheap.

Reply to
Tiger

Ok... this is what else I found so it hopefully helps someone else out here... We drove about 200 miles without any electrical on Tuesday when all of a sudden it all came back on. We had full power for 2 hours and then it started to fade again. What I found out after calling a dear mechanic friend (Frank) in Lansing Michigan is that the voltage regulator on the alternator was probably bad. 2 screws to remove it and $70.00 later for a new one at NAPA and it is running like a champ!

Thanks for all the input here. Good luck and happy driving to all.

Jim

Reply to
yobpner

Ahh! I know Frank personally. Like I said, if you have a voltmeter, you can tell what is the problem.

Reply to
Tiger

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.