W115 300d glow plug light stays on
 

I just bought a 1976 300d. Fires up and runs great but the glow plug light doesn't go out. Today it was 74 outside and the light stayed on for 2 minutes. I shut her off after she fired up and the glow ug light was again on for ~2 mins.

I have the old loop style glow plugs which I just replaced. I have continuity through the glow plugs and I have power at the wire at the firewall.

The only things I have no checked are the ground strap at the 1st plug and the glow plug relay.

Could anyone lend me some advice here. I've googled the light staying on but no one seems to have this same problem.

Does anyone have any info on the glow plug system at all? Everything I find is the w123.

Is there a glow plug relay in the older style loop glow plugs??

A wiring diagram would give me everything I'd need really

Just checked voltage to the plugs and I'm getting 12-8-4.4-4-.5 does this look normal?

At this point I think the glow plug system is fine and that it is something with the glowplug temp sensor that is making the light stay on so long. (I replaced a connector to the temp sensor in the block)