'77 300D Glow Relay

[Krueger]

My 1977 300D is not starting due to a problem in the Glow Circuit. I replaced all five plugs, the 50amp fuse and the power and ground cables to the plugs, however the indicator light in the dash does not come on and the car still will not start. At this point, I'm thinking it could be the Timer Relay, however I'm not sure where it is located on this model. I've received various information - some people say it's behind the dash, others say it's in the engine compartment on the driver's side wheelwell. There are two relays on the wheelwell, I'm not sure if they have to do with the glow plugs. It seems like the wire bundle for the plugs goes into the dash. Before I take that apart I would appreciate if somebody could help me out. Thanks.

[Larry Delor]

I tried to help you out, and went to see what fastlane had to offer for your 300D...But...it gave me a variety of options. You need your VIN number to be sure.

The under dash one is a little harder to find used. The other kind that most of us see, is fairly easy to find used. (both are not too outrageously priced) There is a 3rd kind that appears to have been used for just under 50k units....its is darn near 3x as expensive as the other ones.

I wish you luck, and hope you find the cheap relay!

I added a pic of the most common relay...hope you find this one.

[Krueger]

Thanks Larry. Where's the relay on your 300D? The picture you sent shows a fuse in the relay - my car has the fuse on the firewall. Are there two fusable links in the circuit. If so, maybe the fuse in the relay just blew out - that would be a cheap, quick fix.

[Wodnek]

I too have the same question on my 78 300D. It works like 20% of the time. I got a #8 wire and hold in on the positive batter terminal and on the glow plug fuse on the firewall. I hold it there for 30 seconds and the car starts right up. The two relays on the wheel well under the plastic cover seems to be unrelated.