Diesel 300 where did you purchase your 3 capacitors from. Currently I am experiencing the light in my dash sometimes does not go on but if I turn the key on and off sometimes 3-4 times then the light goes on I wait couple of seconds and then start and having it plugged in couple hrs. before it kicks off pretty quickly Im not sure if it would in less then 20 degree temps. W/O plugging it in and do not want to find out and make the engine struggle in these very cold temps. we are currently having in chic. area. Just had a situation which was my fault that my fuel gelled up on me had to truck the car home and warm the snout out of it in a garage to get it started not fun. I think I want to go to a manual glow system not sure if you can rig it that the light on your dash still works to let you know if all glow plugs are working as if they are not these are hard starting engines in less then 30 degree weather any thing under 30 I plug it in had no trouble this morning starting at about 17 degrees.

The values of capacitor used in the glow plug relay are ones we keep in stock at my workplace, so I just coughed up the 35¢ and soldered them in.

You might try Radio Shack if you have one around, or being in the Chicago area, you should have an electronics supply house or two. If all else fails, try Mouser or Digi-Key, you'll wind up paying more for shipping than the parts tho.

7µF or 4.7µF, I cant find a 7 and I haven't opened up either of my relays to check. I'm going to attempt to source come caps locally and hopefully solder them in tomorrow.

I can only speak for the relay for the 603, but it was a 7µF. I used a 4.7 paralleled with a 2.2 (comes out to 6.9).

Opened mine up today and replaced the caps, I'll install it later to see if it works. Found the caps locally used a 100uf 35v and a 6.8uf 50v

Tested the old caps, both of the 100uf caps were dead and the 7uf tested at 1uf

That's pretty well how mine was too. GP relay has been working fine since the caps were replaced. Let us know if yours works.

7 uf. ?? Never heard of that one.
Standard value would be .47uf or 75uf.
Does the print on the capacitor appear to be faded, etc..?

There's some weird stuff out there. It was VERY clearly marked as 7µF, no fading or damaged text. Definitely a weird value, that's why I subbed the 4.7 + 2.2. Repair hasn't missed a beat, so it seems to be the right value.

Ill take a closer look at the ones I removed today, I didnt even bother to look when I was replacing them. So far so good with the 4 starts I've made since replacing them. I'll find out in the morning when its 20 outside. I also made a video of replacing the capacitors if anyone was curious.

Now I have no output from the relay to the dash light, I'm half tempted to cut the trace on the board and solder it to the output for the glow plugs but I'm unsure of the indicator light output voltage on a properly working relay. I do not see any voltage regulators on the board so I assume it's not a 5v output to the light.

It's a 12V bulb. On my '87 300D, I wired an additional idiot light to glow when the #1 glow plug was energized since I had an afterglow relay.

Sixto
83 300SD
98 E320 wagon

Well **** I'm just going to wire it straight to the glow plug output

Did you get the capacitors in the correct polarity when you replaced them? There is a right and a wrong way.

Yes I did, marked the board before removing the original ones