W124 totally dead

[invisik]

Hi all,

My 1992 300D 2.5 Turbo is totally dead. Had the glow plugs changed at my indy last week (second or third time I've had them change the plugs for me) and the car ran great for about 2 days after getting it home. I had them put in Beru as that's all I could get on short notice--I historically used Bosch.

Now I got no start, no dome light, no headlights, no brake lights, no clock, no buzz from the dashboard or dash lights, no click from under the hood when turning the key--nothing.

- I cleaned the battery terminals with the battery terminal wire brush cleaner and the battery cables.
- I left the battery charger on it overnight on 2amp and it says it is charged. My volt meter says like .02 but I'm sure I have something screwy with it as I have a love-hate relationship with it (more like hate-hate).
- I checked fuses and the big strip fuse just outside the fusebox and they appear good.

I have not tried jumping it yet from my 560 as my jumper cables aren't long enough. Battery is new this summer so is alternator. Battery is Mercedes brand, alternator is rebuilt.

It's pretty cold up here but my garage is heated, about 30-35 degrees all the time, so shouldn't be too cold.

Are there any other main fuses outside of the fusebox that could cause this? Or something during a gp change that could easily get bumped or not reattached?

I'll work on trying to jump it... otherwise suggestions welcome.

Thanks.

-m

[invisik]

Anyone know which fuse is for the glow plug relay?

I put my battery charger on the Start 50amp mode, figuring let's put some juice into the system (as it turns off on 2amp mode when it thinks it's charged) and I got dome lights. Something on the drivers side of the engine compartment was buzzing a little but stopped before I got over there.

I put my volt meter on the battery and it showed 14.5 with the charger on. I turned the charger off, and the voltage dropped about a volt every 30 seconds. This would indicate a massive power drain....right?

If I can locate the glow plug relay fuse, I suspect that could be the drain.

Thanks for any assistance.

-m

[BridelessRacing]

Remove battery go have it load tested if it tests good. clean cables and grounds. Let's know results of this

[Jeremy5848]

Sounds like a bad battery. Swap in the battery from the 560 and see if it will start or at least crank.

[barry123400]

Charge the battery with one terminal disconnected. See if the charge will stay up I suspect it will. You possibly have a very heavy constant drain.

Also stop draining the battery down. They do not like the treatment and many will not tollerate it.

[invisik]

I have started charging with one terminal disconnected. It's the quickest thing I can do right now.

Maybe it really was flat dead and my meter was not lying.

How can I disable the glow pug relay as that is my suspicion for the drain? (esp as there is no fuse for it)

Thanks.

-m

[mobetta]

there should be a fusible link for the GP relay, mounted right inside the relay? but maybe not on that chassis.

[invisik]

Other searches revealed 1991+ have an internal self-resetting circuit breaker... so not much luck there.

There must be a hot lead that comes to the gp relay that I could disconnect. I think I have a schematic for it, actually. I'll have to dig it up.

-m

[scottmcphee]

Sounds like your GP relay gets stuck on. Drains your battery.
The GP relay has a 80A fuse link in it.
The GP relay is on driver's fender, follow the GP leads back to it.

[invisik]

According to other threads on the forums here, the 91 and newer years don't have the fuse, they have an internal circuit breaker.

I did find some two-lead connector that is on a little clip next to the glow plug relay and unplugged that. I switched over the battery charger power to energize the car, and then plugged that connector back in. I then switch over to battery power (have 11.5 volts charged up so far) and monitored with volt meter, it is not draining.

I'm leaning toward the glow plug relay is sticking on as well. Are there any remedies to this other then buying a replacement? Or something temporary to make the car drivable until the part gets here?

Thanks.

-m

[invisik]

Charge is holding now in battery when connected to car. It certainly could be the gp relay..... Should I order one?

-m

[compress ignite]

I'll not CONDEMN any electrical appliance (Much less order one for $Dollars$)
UNTIL I have proof positive from EXHAUSTIVE DMM [Digital Multi-Meter]Testing
results!

(Without Empirical testing results,You can "Throw" Hundreds+ of Dollars U.S.
at this chassis and NOT FIX ANYTHING!)

All that you KNOW,right know, is that you've some kind of Electrical Anomaly
[Electrical Difficulties that do not follow the paths called wiring have three names: 1. Lightning 2. EMP Pulse 3. Divine Intervention.]

FSM page OnLine that deals with Pre-Glow Relay Testing:
http://www.ps2cho.net/downloads/MB%20CD/W124/w124CD1/Program/Engine/602_603/15-4000.pdf
You want to utilize SECTION "B" because your Relay has "AfterGlow".

Before I'd BUY a new one
(Even if the old one was sticking...
[SEE JEREMY's post on AfterGlow indicator light:
http://www.peachparts.com/shopforum/showthread.php?t=236848&highlight=afterglow]
AND I could "SEE" the ReLay sticking...]

Take the relay apart GENTLY and clean the contactors and apply Stabilant 22
to both the High and Low Amp contactor (s).

AND you're correct, the RED wire feeds battery Voltage and Amperage to
the ReLay, At All Times. (No 80 Amp Fuse).

Electrical problems are much like Pyramids , they must have a stabile/firm
base to build upon (No Shortcuts).
Sometimes you have to Start from ZERO (Grounds) and work your way up!

I see that you've been a Fomoco customer in days of yore, so you've probably a much nicer DMM than I do.
BUT if not ...Sears and Harbor freight regularly have sale on them for less than $20.

[Skippy]

I just looked up the glow plug relay for a '92 300D. $152 from allparts express. If you do find yours is bad, and don't want to spend the money, there is a redneck way:

Momentary switch at the operator's station, a roll of wire, some zip ties, and a generic relay. (Just for kicks I looked up a suitable one (listed as a starter relay for an '86 Crown Vic) for ten bucks at Autozone.) Assemble to taste. Total investment should be in the ballpark of $15-20, less if you shop at the junkyard and wear baggy clothes. A PO of my 240D did this and it lasted the remaining life of the car.