I have the pin style glow plug kit for my 77 300d but am conceptually unclear on a few issues. I understand the old plugs and grounding strap are to be removed and new plugs installed, but the wiring from the plugs to the vehicle is unclear to me.
It looks to me from the directions, that all the existing system is bypassed, the new timer wired directly to the battery and into the fusebox. This bypasses the heavy 80 amp fuse. Is this correct?
When I bought the kit from Foreign Automotive Parts, I was told I would need an additional relay for my vehicle, but there is no mention of it in the directions. Does anyone know if I really do need this additional relay and how it is wired in?

With the existing glowplug system bypassed, does the wiring into the fusebox result in the key actuating the new timer and heating the glowplugs? There is no explanation in the Bosch paperwork of how this new system works once installed. There must be an existing timer of sorts somewhere in the system, is this being bypassed somehow or is the relay I was sold intended to take the place of the existing timer? If so, where is the existing timer on a 77 300d?
As you can see, I am confused.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Kerry

I have installed the new style plugs in a couple cars. I used the old relay and just disconnected the old ground strap. You should put in a 80 amp strip fuse. I gota admit, I couldn't out the wiring for the new relay and don't consider it worth the energy to pursue. Now when glowing you must remember to just glow for 5 to 10 seconds.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

That does raise the question about what is the difference in the relays and why not hook the new pin style plugs directly to the wire coming off the strip fuse? Will it do any damage to the plugs to operate them that way?
I'm not sure what you mean by 'only glow 8-10 seconds'? Doesn't the relay and timer determine the length of the glow? Do you mean, start it after 8-10 seconds because you don't need to wait any longer anymore?

By the way, stupid me. I found a second set of wiring directions in the box. The first set I read were for 4 cylinders and the second for 5 cylinders. They are VERY different with the 5 cylinders requiring the relay. So now I do know exactly how to wire it. But I still don't know why. Does anyone know why the wiring diagram is SO different for the 5 cylinder? How does adding one more plug make such a difference?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Kerry

If you want to put off/ forget about the new relay, simply throw away all those resistor wires, unhook the ground strap and put the new GPs in using the new wires (the black wires between GPs). Thats it. The old relay will glow them for too long ,all you will need now is 10 seconds or less. Put in the 80 amp fuse too. None of my MB friends around here have used that new relay, maybe were all bunch of cone heads

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I pulled the wiring harness off an old 300d and modified it to work on my 77. Worked great, old relay would only glow plugs about 1/2 as long as it did the old style plugs. No problems.