BenzWorld Senior Member
Date registered: Jun 2004
Mentioned: 0 Post(s)
Quoted: 17 Post(s)
I have had experience with the glow plug systems on the earlier W110 bodied cars and I believe this system is virtually identical. On those cars you have the glow plug resistor located on the dash and another resistor located on the engine side of the firewall. There should be 8 VDC coming out of this second resistor, which connects directly to the glow plugs. If you have 12VDC there (or at the first glow plug), then the firewall resistor is shorted and sending too much power to the glow plugs, which will burn one out quickly.
Check the metal guard on the firewall resistor. Sometimes they can come loose and touch the resistor, shorting it. Another place to check is to make sure that none of the connecting wires between the glow plugs is shorted to the engine block or head. If one is, this will put too much current through the others and burn one out.
Last edited by KCM; 02-15-2011 at 08:17 PM.