Where's the fuse for my glow plugs?
 

I've seen a photo or two posted on the forum, of different models, that have the fuse with the glow plug pin module box at the wheelwell area. But on mine, I don't see any fuse in that box. Where's the fuse for my glow plugs? If you look at the photo I attached (2 replies down), on the upper right you can see I have no fuse!! I guess it disintigrated or something.

How do people post large photos here? If I try that, the forum says it can't take that large a photo.

jeff 1991 300d, 128k

Strip fuse on the relay.
Picture courtesy of DieselGiant./

http://www.dieselgiant.com/glowplug09.JPG

Are you sure???
 

Maybe that's why my plugs aren't glowing, because there's no fuse there! Yikes. What happened to it? I heard mine is a 30 amp fuse, not 80 like the older ones.

jeff

How about a more complete picture of the thing?

its an 80 amp fuse. 30 amps would barely make the plugs warm

Electronic Pre Glow Relay (NO 80 Amp strip fuse)
 

jbach36,

Your "Pre Glow Relay" is Electronic (No Strip Fuse) It senses a / an Over Amp,
Over Voltage situation and disconnects
[and then resets when correction occurs]
'Kinda neat (But I don't know the inherent fail rate)
(And I can't find replacements)

My '90 124.128 has one that works fine.
(And I saw one in a '92 124.128 in Texas yesterday)

So to be on the safe side,I'm going to "Fuse" the RED cable [HOT at all times]
[Power to the Pre Glow Relay]with an 80 amp fuse ,just in case.

How do you post bigger photos?
 

I would if I knew how. The forum only allows like, 86k or so, but other people post these real big photos. I'll see if I can do a link on my web site.

jeff

I have a 95 E300d and am experiencing the following problem with my glowplugs just in the past few weeks of cold weather: they do not come on until 30-40 seconds after turning the key on.

how I know this: the dash light does not come on either. Today I tried to start the car and it would not start. I turned the key off and then back on(dash light not on), and pulled the hood release and got out of the car and opened the hood. I then heard a loud click and looked inside and the light was on.

It still wouldnt start because it was 14F and I have B100 in it :D and I just got caught unprepared, but I still have a problem with my glowplugs. Should I test each one, or is this relay bad?

glow plug relay
 

If I remember correctly all of the glowplugs have to be working for the light to come on right away. My wife's 91 300D (603.960 greymarket from Japan) glowplug light would not light up until I replaced a couple of the plugs. That way you know that something is wrong. The rest of the plugs would heat up but the light stayed out. You should be able to test each plug at the relay itself as there are individual wire connections to each one at the big power plug. Cheers Dan

Nope, fuse is in a different place
 

No wonder I couldn't find the fuse. It's not located where the other normal cars are. Mine is in a separate box over the wheel well.

Thanks,

Jeff

Where is my glow plug fuse? (really)
 

I think my car is different than others. I've seen the photo 100 times where "the fuse is", inside the glow plug relay area, a 30 amp strip fuse. Only problem is, on my car, there's no fuse there. I do have 2 screws in that area. I thought maybe mine disintigrated. No fuse there.

I went to the German parts place, got a fuse, but it's 1/2" short. Won't even fit. I thought maybe they got me the wrong fuse, but they checked several sources, that says it's the correct fuse.

I went somewhere else, he showed me that there's a separate tiny box for a single fuse, over the driver's side wheel well, for the glow plugs. The fuse will fit there perfectly, though the one already in there is in fine shape.

So I thought that was it. .... Until.... someone private messaged me, that the separate fuse in its own little box is NOT the glow plug fuse, but the fan blower fuse. I disconnected it, and sure enough, the blower fan won't work.

I give up. Where is my glow plug fuse? If in the relay box area as many pictures show, then why is the 30 amp fuse I have too short? Again the 2 screws I have, shown with arrows, seem to just hold the box together.

Thanks,

Jeff 1991 300d, 128k

According mercedes literature it should with the glow plug preglow delay relay, the black box. An 80amp fuse

Am I correct in recalling a recent post in which someone wrote that later models have a circuit breaker and not a fuse?

30 amp
 

I heard in later years, they went down to a 30 amp fuse. I'll check, maybe that's why the 30 amp won't fit there!

jeff

Yup, you don't have a fuse, just a self resetting breaker.

-Jason

The external ACC blower fuse is a 30 amp strip fuse.

Someone posted that a replacement glow relay came with a strip fuse.

Sixto
87 300D

Here's a thread with 2.5 relay pin information -

http://www.peachparts.com/shopforum/diesel-discussion/241065-93-300d-2-5-turbo-wont-glow.html

To test these wires -

1 = pink/red, +12V from fuse 7 = should see +12V with key in run or start (starts glow cycle)
2 = violet/white, +12V from key switch = should see +12V with key in start only (starts afterglow cycle)
3 = black, +12V to dash glow indicator = sends +12V to glow bulb during timed glow
4 = brown, ground at W3 (beside glow relay)
5 = white, ground from preglow temp sensor B11/7 (beside thermostat) = not too sure about this one, either grounds with coolant above 50*C or grounds while coolant is below 50*C

Sixto
87 300D

http://www.allpartsexpress.com/ShopByVehicle.epc?q=&yearid=1990%40%401990&makeid=MERCEDES+BENZ%40%40MERCEDES+BENZ%40%40X&engineid=1 193723%40%40300D+2%2E5+%2F+L5%2D2497cc+2%2E5L+DIESEL+FI++Turbo%40%40300D+2%2E5&keyword=glow+plug&sub catid=Glow+Plug+Relay@@Glow+Plug+Relay%2FCentral+Electronics&mode=PA

I dont see any resetting breaker in a new gp relay unit. I see a relay unit with a fuse

Correct for the 140 model diesels but he has w124 diesel model

the wiring diagram for the 140 shows no fuse as for the w124 there is a fuse.
I can prove it...

Compu 85 has it right.

Check agian

Fastlane shows a fuse but the that car doesn't have one for the glow plugs. The circuit breaker is part of the afterglow system. Ask anyone who has upgraded their afterglow.;)

nvm not gonna argue with someone who refuses to look up info on it or at wiring diagrams about the glow plug system. I am taking my info directly from mercedes dont know where you getting yours.

http://www.filefactory.com/file/a007fhg/n/0705_-_Function_of_Preglow_System_Engine_602_96_603_96_97_TURBO_Model_463_3_for_deviations_see_introductor y_notes_pdf

Go look at the picture in post #100 and #106 of this thread. Then look at the picture that Jbach36 posted above. Do you see a a spot for a strip fuse in either relay?

The ETM diagram in my copy of the 124 FSM on CD shows an 80 amp fuse in the 86-89 relay and no fuse in the from 90 relay. It doesn't show a circuit breaker as a discrete device. The controller device has a relay function that sets a switch between the power source and the glow plugs. Anyone's call how representative the ETM diagram is.

I've heard of aftermarket replacement 2.5 relays with strip fuses. I don't know of anyone with a dealer replacement relay. Maybe Phil can settle this.

edit - corrected year ranges in ETM diagrams. This change throws off Oracle12345's quote in post #32.

Sixto
87 300D

Also read post #6 above. He has a '90 and seems to know how his glow system works. Sometimes in life we have to step out of the paper world and into the real world. Nothing like opening the hood to see what is there.;)

The W124 and W126 got the afterglow relay, with the self resetting breaker in 91.

'Just a little verification
 

For:
compu85
and
BIO300TDTdriver

AND sixto you're correct too,
The Electronic "Short Circuit Protector"is built into the Pre-Glow Relay itself.
The only clue,visually, is the lack of the usual 80 Amp Strip Fuse.
(and it's Two securing screws)

[All the credit for this "ReDiscovery" must go to Arthur Dalton,He set me straight
when I was Flailing Around Frantically looking for my non-existent GP relay fuse.]

Thank you,

I didn't feel like digging tonight. That sure sounds like a circuit breaker not a fuse. Seems like I've heard that somewhere before.;)

jbach36; I have a 92 300SD and I have the same box. There is no visual fuse, is an internal relay due to the fact of afterglow feature. System the activates on cold weather. Glowplugs need full battery charge or they will not came on. Check dieselgiant.com for trouble shooting procedures, you will need a multimeter tester. (skip the step of the fuse). Good luck Victor vmcastillo@verizon.net

thats what im seeing

basstrip you have w140 which didnt have the fuse

ok,
it's best to take a big picture and upload it to photobucket.com then click on the img tab and then paste the text from there into the message window here. voila! large image posted to the thread.
http://i135.photobucket.com/albums/q...hotobucket.jpg
and here,
http://i135.photobucket.com/albums/q...buckettags.jpg
is the spot where you click on the IMG text, and pb.com puts it into your clipboard for you to paste into the message window on the forum!

I know it's old but same year same part... glow plug relay 95 E300D
 

Haven't been online for a few weeks now, getting ready to move to Kentucky. Yesterday a problem popped up and never went away.

No fuse on my relay either.

Yesterday, typically starting cold, glow plug dash light would come on and stay on after starting.

Sometimes it would not come on, but it would still start.

Read a while on the internet & decided to follow a few of the suggestions.

Found glow plug four failed resistance test.

Last thing I did was pull the glow plug relay, take it apart and clean contacts thoroughly with both alcohol and contact cleaner sprayed on thin paper.

Put it back together, added a mickey mouse led, and tried a cold start.
Dash light came on, dash light went out, I started the car.

Dash light went out. I checked outside and the LED was bright red.

I watched for about two minutes and it went out.

Checked inside and the dash light was back on. Checked LED again and it was still off. LED shows me the glow plugs are heating or not.

I'll update in a few days once I learn more.

When one plug is bad, you won’t get the preglow light when you start. Once the engine is running, the light comes on and doesn’t go out. Now you know the secret code, replace your plug and be happy.

The light is not consistent.

Sometimes, when cold, it comes on like normal and goes off after a little while, then comes back on and stays on.

Other times, when cold, it does not light but starts easily. After a while light comes on and stays on.

Hopefully the glow plug relay is ok, time will tell, probably won't attempt #4 glow plug change until sometime this winter in central Kentucky. At least the glow plugs aren't heating all the time.

Thanks for your comment.