It appears fussing with the fuses resolved the problem I was having. I'm just not sure why. That's what I was trying to figure out in my previous post. Car starts now without any issue as before. I never needed to jump it.

None of the fuses were blown. One or more were apparently corroded and cleaning them resolved the non-start issue. Still scratching my head.

95 W124s have a starter interrupt relay behind the instrument cluster. If you had a bad connection to the power feeding the anti theft controller, then the relay would not have pulled in and you would not have been able to crank.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

jay-bob: Thanks for that info. Do you have any idea if that relay's power is routed through the main fuse panel? I pulled the fuse cover off and ran down the list of circuits protected by the fuses and don't see any reference to a starter interrupt or anti-theft feature. I'll look through the wiring diagram in the manual later to see what I can find. It was just surprising to me that the issue went away as soon as the fuses were cleaned. When it occurred I had been thinking relay or other electrical issue, since some of the warning lights did not come on when I turned the key to the run setting and I got some weird buzzing out of the intermittent wiper, hazard lights and rear defroster relay.

jay-bob: Just pulled up the anti-theft wiring diagram for the '95 E300D on autolib.diakom.ru's site. It shows that there are four fuses involved in the this circuit--C, 5, 11, and 12--all providing power to various connections on the anti-theft control unit. (Interestingly, my fuse tray cover notes that 11 and 12 are vacant, but I have a fuse in each.) C, 11 and 12 are hot at all times, so a faulty or blown fuse could affect power to the relay you've described. However, the wiring diagram does not make any reference to a starter interrupt relay that is part of this circuit.



The '95's engine performance circuits diagram from the same source shows only a violet/white wire running to the starter from the pre-glow time-limit sensor module. No other wires or relay connections. This is not to say these are correct. Just reporting on what I found in the tech info.

Definitive answer for one possible cause for a non-start in the '95 E300D. With some time to poke around under the hood this morning, I pulled the four fuses mentioned in my last post--C, 5, 11 and 12--one at a time. Result: A bad or corroded #5 fuse will prevent engine from turning over. Removal of the other three fuses mentioned did not interfere with a normal start.

Among the circuits the #5 fuse covers is internal lighting, part of the anti-theft system. I do not see a direct connection to the starter, but this may be handled internally by the anti-theft alarm control unit.

Late production W124s have an alarm module under the passenger front carpet. If you get problems again I would look in that direction.

It would be a good idea to have a known good spare module.

__________________
David Hendy
'97 Renntech E60RS
'97 GMC 2500 Sub' Diesel
'95 E300D
'88 300TE
'88 250TD
'84 L/Rover 109