Ive had an old W123 standing for a year, and it wouldnt start. I swapped the starter motor (the old one didnt even click) and now Im not even getting a battery light - no electrics whatsoever. It looks like the car already has a hard start relay put in, but now Im not even getting a battery light on the dash.

There's a new battery in it, so plenty of juice, but I could do with some pointers of what connections to check, and how to measure voltages in the right areas...

Fuses?

If it's been sitting for a while, replacing all the fuses and cleaning the contacts is the first thing you should do.

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-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon

Glad to try and help one of our good Polish friends.....
Start by checking the fuse box to see if you have voltage going to it....Do you have a voltmeter?...also pull the fuses one at a time and clean the fuses and contacts they fit in to begin with.....post back and we will try to walk you through.....these problems are my favorites....kevin

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

Forgot to mention the grounds for the battery...remove and clean all grounds down to bare shiny ,metal...coat with heavy grease after reconnecting...Remove and clean all ground straps to engine,transmission,head, alternator,chassis...wherever you can find them...never hurts to add extra grounds all over......this is important ....with one this old........

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

In effect if I remember the positive cable sub divides. I have had to repair it as those connections rotted so bad there was no current flow. You can splice them in lower on the positive cable if I am right. At this point I am not even positive it is the 123 model I am thinking about. Yet a 1977 300d comes to mind. A meter or test light like yellit mentions should locate your open circuit. Beats guessing.