My wife told me yesterday that her car has started to not start as fast as is used too. Last night when I took it to the store I noticed that the glow plug light didn't come on. Thinking this was a little odd, I opened the door and recyled the key. I didn't here the "click" that the GP relay normally makes. WHat are some other things to check out? The GP's are new as of last summer. So it shouldn't be that. If it is the GP relay, where is it, can i test it, and how much does a new one cost. Would a junk yard part be just as good as a new part?

Thanks fo the help.

The glow plug relay is on the driver's fenderwell, forward side. It is a rectangular box, approximately 2" x 4" x 4" deep.

Connect a voltmeter to one of the glow plugs. Turn the key to the #2 position. See if you have 12V at the plug. If you do have 12V, then one of the plugs is suspect.

If you do not have 12V, check the 80A fuse that is underneath the cover of the rectangular box. It is a copper? plate that sits between two large phillips screws. Sometimes this cracks with age. Sometimes you cannot see the crack. Take it out and look it over carefully. If you have any doubts about it, replace it.

If the fuse is good, then the relay is suspect. A junk part will function as good as a new one, however, the new one will last longer.

I read in a thread here recently that the dash glow light will not come on if two or more GP's are not working. With only one bad GP, the dash glow light will still come on. Chances of two recently new GP's failing isn't likely, and as Brian has already mention, the fuse inside the GP relay box may be blown, or have corroded too! Hopefully it is corroded because if it is blown there is a reason for that such as the relay it's self going bad! BB

Thanks for the replies. I will be checking the fuse ya'll are talking about when I get home this evening. It shouldn't be the GP's as I replaced them all lass than a year ago.

I don't know if it's a realted problem or not, you know how these MB's can be. The car is a wagon. Last week my wife calls me at work to tell me that the rear cargo light is on and it won't turn off, no matter what she does to it. She finally had to remove the bulb. Is this a tattle tale for something or is this an unrelated problem?

I was pokeing around last night under the hood and have a couple of questions. I found two boxes on the drivers side that are approx 4x4x2. One of them has two fuses inside of it and I can't tell were the wires go too. It's mounted on the top of the wheel well. THe other one is mounted vertically on the side up close to the headlight. I can trace out the wires leaving it, and they go directoly to the glow plugs. I have a feeling that this is the box that's being referred to above. Is the 80A fuse inside of this box?

Also, On the passenger side mounted to the fender is a little metal box. Approx 3"x3"x4". It has a bunch of holes in it and has what looks like some springs (or coils) inside of it. I think this is the little device that used to click when the GP's where activated. But right now I don't get anything.

Please shead some light on this for me.
Thanks,
Chris

That's the glow plug relay. Slide the cover off to reveal the 80A fuse.

That is the resistor bank for the fan motor that moves air for the climate control system. When you run the fan at any speed less than full speed, some of those coils are in series with the fan and cut down the voltage to the fan.

The 80A fuse looks like this.

http://img.eautopartscatalog.com/live/thumb/P201511766.JPG

It's held by two philips screws, one at either end, and at first does not look like a fuse.


Best Regards,
Jim

Thanks for the photo Jim. At first I thought the link you posted was bad, but then I noticed the faint picture. I do remember seeing that little bar looking thing last night & it was neither blown nor corroded. Where do I go now?

Post #2.

Roger that.

I rechecked the fuse last night now that I know what it looks like, and it is fine. I have a cheap little multi-meter to measure voltage, ohms, ect., but fo the life of me I can't really figure out how to use it. It was given to me w/ no instructions & I have never been accused of being an electrical genious. So I think I'll wait until this weekend and pull a few GP's and hook them up to a battery charger. It's a poor mans test.

If the GP's check out fine, where do i go next?

Thanks for the help
Chris

You really need to run the test with the glow plugs in the vehicle. The meter should not be all that difficult to figure out. It probably has an input for ground and an input for " DC volts". However, there may be a couple of inputs for "volts" depending on the scale thay you want. Try to find a scale that goes from "0-24" or "0-50" and plug the lead into one of those ports.

Put the leads on the battery (one to + and one to -) and see if you get anything on the meter. You should get about 12V.

Now put one lead (+) on one of the glow plugs and leave the other lead (-) on the battery - terminal. Turn the key to the #2 position and see if the meter reads 12V.

Then we will proceed from there.

Thanks for being so patient with me. Tonight I'll go and try to figure out the multi meter again. Last night while trying to figure it out, all it ever did was peg the needle. And that's only if it registered at all. I didn't know what to set it on so I went through all the settings to see what it did. It was either all or nothing.

I'll try what you suggest about using the battery. If all else fails, I think a friend down the street might have a digital one.

I'll post my findings.

Well I got it fixed. It turns out that my multi-meter was working corectly the whole time. When I thought it was "pegging out" it was actually giving an infinity reading. All of my glow plugs were bad. I replaced all of them and all is well.

Thanks for the help.
Chris

Fantastic.

Five bad glow plugs? These were supposedly new last summer?
What brand were they????

It must start like a dream now.

is there an 80 amp fuse on the 240? i have had the relay out twice but never saw a fuse. my car will not start in the cold w/o ether. po said there were new plugs when i bought in oct.

__________________
currently
[1981 300 td tdidi 165500 dark brown/palamino-Brownie-mine-3k miles of ownership
1983 240d 162+++ Anthricite grey w/ henna red interior and hella lights-wifes car-Red

the above two cars are for sale
and can be seen on the cars for sale thread here. pix also available.


240d-144+ Manilla Yellow w/ palmino interior-greasecar kit-Blondie-the college kids car

23" gt 21 speed still on original tires-still got the nubs
21" khs tandem