My 77 has the upgraded pencil glow plug and original relay. Recently the glow plug light wouldn't come on unless the starter is engaged. The relay isn't providing juice to the plugs when the key is in "glow" position but if you take the relay out then the car won't start. Any ideas on what is going on here? Also can't hear the relay trying to click in glowing position and I have tried unhooking the temp sensor so the relay would think it is very cold out, no dice.

__________________
1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C

I would first make SURE the GPs are good. Try a used relay from eBay or the bone yard. You could use a push button switch and forget the relay but you'd need a solenoid for the new 8o amp GPs.

__________________


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 would not rule out the possibility of a fault in the ignition switch. We know from repeated posts on this board that the switch can fail, causing the starter not to engage. It seems equally possible to me that the switch can fail in such a manner as to fail to energize the relay. I'd try bypassing the ignition switch and providing 12 volts directly to the relay. If it works, the likely source of your problem is the ignition switch. The fact that the light glows in the 'start' position seems to show that the problem is not in the relay itself.

__________________
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

Have you checked the copper fuse, on firewall directly behind the engine (small black box)? Mine failed years ago, replaced it and no problem since, I have the pencil type in my 77 300D.
Ron

Thanks for the replies. It turned out to be fuse #14 was blown. Repalced and life is good. Can't figure out why the relay worked only when cranking but that is for another day

__________________
1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C