Concerning a 1985 300d:

My understanding to that question is "no," but I have seen the question asked here before, and don't recall a clear answer.

The charging system doesn't work when the dash light bulb is burned. (That is my understanding anyway.)

Does the glow system depend on the bulb in the dash being functional as aprt of the circuit as well?

My comprehension is that it's an indicator light only.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

The dash GP lamp is for the driver to realize what is going on in the system only it is not required for normal operation of the glow circuit.

The previous thread is true.

On your Year and Model there is a Temp Sensor inside of the Glow Plug Relay that dictates when the Glow Plug Light goes out. However, the Light does not control how long the Glow Plugs stay on.

If you keep the Key in the Pre-glow postion the Glow Plug Relay stays on until the internal Timer turns it of. The Total Time the Glow Plugs are on is about 30 seconds till the Timer turns the Glow Plugs off.
If you want you can turn the Key bace and start another 30 seconds of Glow Plugs on.

This has nothing to do with the Glow Plug Light but when you are Cranking the Engine with the Starter your Glow Plugs are also on.

The Glow Plug light also has trouble shooting. Someone else will have to give the specifics. But, when you turn the Key on if the light acts abnormally it means something and if after the Engine is running the Light comes back on it means something else.

__________________
84 300D, 82 Volvo 244Gl Diesel

Light is an indicator only. All 5 wires going to each glow pug are ganged together at the output of the relay; so effectively if you have power to one, you have power to all unless you have a broke wire or bad connection. If the current sensed is correct, the light comes on. If the light comes on for only a second or 2, then you have a plug burned out. When you turn the key you can hear the glow relay click, but kind of difficult to hear from inside the car. Easy way is to put the key in the on position. Remove the cover from the relay and remove the control plug and then plug it back in. Relay will turn on and remain energized for about 30 seconds and then click off. While its clicked on, you can measure the voltage at one of the glow plug studs. No click, bad relay or control signal from ignition switch or input power. Good click, no light, probably one or more bad glow plugs. Get the genuine bosch plugs.
Hope this helps.
Mike

I've got an 85 300D in that I will be troubleshooting over the next week or so. The glow plug light does not come on at all on it.

__________________
Jim

Instructions I posted are for an 85.
Mike

Check the glow plugs with an ohm meter, diesel giant has a decent write up.

__________________
83 SD

84 CD

I could not find the other part of this.

A fault in the pre-glow system is indicated by the Light not lighting up when the Key is in the 2 Position (when you are pre-glowing).

The Following Faults are recognized:

Interruptions (I take this to mean open circuit) of the Line (Wire, connection) to terminal 30 (the Fuse circuit);

Defective Strip Fuse (cracked, burned or Screws loose);

Power Relay in pre-glow time Relay defective (inside the Glow Plug Relay);

interruptions of one of the several lines (Wires) to the Pencil Glow Plugs;

interruption of one or several Pencil Glow Plugs (bad Glow Plug).

At this time I am unable to find the description of what happens after you start and the Engine is running and the Glow Plug Light goes on. But, from Memory I believe it said there was a fault in the Glow Plug Relay itself after the Engine is running the Glow Plug Light would come on (but I don't think it stays on).

__________________
84 300D, 82 Volvo 244Gl Diesel

The reason I asked the question originally is that, while the system on my 300d seems to be working normally, I am not getting proper preglow. Nowhere near it. Just about from one day to the next the car began to start like it has 500k, not 119k. The problem is not fuel delivery. Road performance is not affected. I changed the relay for a nearly new one and confirmed there is juice going to the glowplugs.

At the time, the possibility of my brand new Bosch Duraterms being defective was in my mind minimal.

However, having recently had some issues with my instrument cluster grounding it occurred to me that possibly the preglow light needed a strong ground for the circuit to function properly (admittedly not a strong theory but it was the best I could come up with to explain my very hard starting as soon as the temps dropped a bit, the cluster issue having happened right before the temp change).

It was only in the last few days that I went looking and found I am far from alone in having nearly new Bosch GPs failing. It isn't a huge wave, but enough people who have experience with the cars have posted that I am now willing to allow that I'm not losing my grey matter. Also it has been theorized that the "bad" plugs are coming out of India and the "good" Bosch stuff is still coming from France. That is leaving aside the possibility of Chinese knock-off parts. I do know that the previous set of Bosch GPs I installed had no seals on the boxes, which I did not like at all. This set had clear plastic seals with some sort of design on them.

As a sidebar, I need to go back and find the boxes where I purchased some cut-price GPs last year from a reputable diesel products vendor on eBay, for my NA wagon. The seller claimed that they were made by Bosch subsidiary in Europe and sure enough when I investigated, I found their website and they were a regional supplier bought out by Bosch. I cannot remember if they were French or not.

Anyway they were about 1/2 the price of Bosch and they are working marevellously (so far) in the wagon. Damned if I can remember the name but I think it started with a "B" (not Beru). As I recall, the boxes were blue and black.

I posted in another thread that Berus can be had but are hard to find and not cheap. The ones listed for our cars as Beck/Arnley also appear to be Beru, but for some reason are listing as more expensive than actual Beru.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I don't know what to say on the Bosch Plugs. The last ones I bought were in the $8-$9 dollar range and were from a well known Internet Auto Part Seller not from eBay. The Boxes had Holigraphic tags and they were made in France.

Anything that is not working right in you Pre-combustion Chamber will shorten the life of Glow Plugs. Ip Timing, Injectors, Carbon Build up around the Glow Plugs, not using Diesel Fuel and Compression all have an effect on Glow Plug Life.
How you drive also does. Long trips on the Highway are better then short trips like My Wife drives 2 Miles to work with maybe a 10 Mile trip on the Freeway once a week.

Too much voltage also shortens their life and if they stay on longer then they are supposed to.

On My Year and Model the Electrical Connector has a Brown Wire that is the Ground for Something in the Glow Plug Relay. I only know the Relay end of it; I don't know where the other end of that Brown Wire attaches to.

Not a bad Idea to clean your Battery to Chassis Ground and the Chassis to Engine Ground points.

I changed Batteries and needed a longer Cable and ended replacing the Chassis to Battery Ground Cable. When it was done I found out I had a whole extra Volt during Charging. Apparently the Old Cable had some resistance issues.

When I installed a new Steering Colum Lock assembly. I took a look at the old Ignition Switch. The Old Ignition Switch was still working but I found that a Contact Point was actually burned off one side of one of the Contacts.
It is pretty clear that, that particular contact was on the edge of failure.
I never took the time to determine what contact that was.

__________________
84 300D, 82 Volvo 244Gl Diesel

Thanks, all good points, 911.

I cleaned my ground connection this summer. and I reamed the holes when I installed the new plugs. My ignition switch is brand new. I swapped out the OE relay for one of those Hungarian ones that is a few months old.

I did not look at the engine to body ground, come to think of it: where is it? On my Volvos it was right up front and center, a big strap from the back of the valve cover.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Under the Car on the Left Side behind the Wheel Well and it attaches to the Bell Housing.

__________________
84 300D, 82 Volvo 244Gl Diesel

Ground was taken off and cleaned today. Looked fine.

Temps have now spiked up over norma for this time of year after being very low, so it may be hard to tell if there is any difference (on cold starts).

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Changed all five gps and it started right up after priming.

thanks

__________________
Jim