I have a 93 300D 2.5 turbo. The car won't start. I think it seems like the gp relay is bad. No light on the dash, no starting just a bunch of cranking. I see the new parts on fastlane and all these posts have an 80 amp strip fuse. Mine doesn't have one. The relay box looks about the same but no fuse at the end of it! What the heck? I don't think I am blind.

Later model cars have no fuse in the GP relay. There is a circuit breaker in there. I am sure that the picture you are seeing may not be the true representation of the GP relay for your car.

The official MB service manual offer a very good step by step method for checking the GP relay. Perhaps someone on this board has one that can help you with.

My car is an 86 300sdl and my relay has the fuse in it.

__________________
John
1986 300sdl
1985 380se

OK. I have done some more searching. It seems mine has an internal circuit breaker. So here are my next questions.

1) is there a way to reset?

2) is this like the fuse strip and just needs to be replaced or the whole relay needs to be replaced?

3) Is there something else that can cause this or rather what is the cause of this to break - just age? The car is 17 years old.

4) Can I put an 'older' style relay with a fuse strip in place of this one?

I do not think so. Your car has an afterglow feature that the older models do not have. Your GP relay gets a reading from a temp sensor in your head to determine the time the relay stays on, the older cars have the temp sensor in the relay itself.

__________________
John
1986 300sdl
1985 380se

You should be able to put a preglow relay from an earlier W124 provided it is a five-cylinder version. I don't know enough about Mercedes model-years to give good advice. The preglow relay from an OM617 will work but you will have to do some rewiring; it will not be plug-compatible.

The circuit breaker in your preglow relay is self-resetting; if it will not reset, you will have to replace the relay. Remember that there may be fuses in the main fuse compartment that cover power to the electronic part of the preglow relay. If one of those fuses is bad, the relay won't work. Likewise, the over-voltage protection relay (OVP) and its built-in 10 amp fuse may need to be good. I don't know how similar your car is to my '87, which is what my wiring diagrams are for.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Why not disconnect the relay and jump the glow plugs (for a few seconds) and give it a crank?

That will at least prove there is a problem with the relay/gp circuit?

It should have a strip fuse in the relay.
Enter this part number in FastLane, click the part picture to enlarge it.


MB# 007 545 99 32
Diesel Glow Plug Relay (Preglow Time Relay)
Chassis W124.128
Model 300D 2.5
Years 1990-1993



Have a great day.

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I hear you on the 'what should be in there' argument. My local MB parts store (A better wrench in Chapel Hill NC) looks this up and they too said it shows one with a strip fuse. That's not what's in it. I'm going to do some voltage testing tonight to determine what is and isn't working. I'll also get a p/n off of the old one to cross and see what it is made for. I've had the car for 18 months with no problems in this department so whatever is in there was working, but sure as hell isn't now.

This is all very confusing. Everyone is telling me it should have a metal strip fuse. I just found this on E-bay (check listing 290325538558) which shows a good picture of the item and you can plainly see the MB part number on the side of if as 007 545 99 32. It also clearly does NOT have a metal strip. Somebody's picture or part must be wrong between these various sources. More grrrr....

Fastlane might be fast, but they are definitely wrong on that one. There is no strip fuse in that year of 124!

__________________
1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

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For Interpolating !

__________________
'84 300SD sold
124.128

A bad/damaged glow plug harness is rare..

The far more common cause of no glow plug light is bad glow plugs.
For more data on this simple issue read the following thread..

Glow plugs link thread
http://www.peachparts.com/shopforum/diesel-discussion/137732-glow-plugs-link-thread-post1019018.html

If you bothered to read the thread, you might realize that the issue has nothing to do with the lack of a glow plug light. The problem is the internal circuit breaker that is tripping due to overcurrent.

You'll also note that this relay does not have a fuse.

A picture of yours might be helpful.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Nor does mine.
It is electronic
(and self resetting,
IF THE ELECTRICAL PROBLEM THAT CAUSED IT TO TRIP IS CORRECTED!)

'Vary rarely goes bad.

Much Nicer than having to fool with the Strip Fuses!

124.128 (s) from '90 to '93 all have this feature.

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'84 300SD sold
124.128