I am in process of tearing car apart to resolve problem. Maybe someone has some ideas? I carry a remote starter to start car. It starts immediately and runs beautifuly but 90% of the time I have to use remote starter. No matter what I do with the shifter, it doesn't make any difference. I have cleaned the grounds(all of them). I hook up a multimeter and turning the ignition switch is not sending any voltage to starter. The remote starter I hook to two posts on back of starter which provides current (directly from battery) to starter solenoid which kicks off engine immediately once I push start button on remote.
Sometimes its a little tricky hooking up my alligator clips because of engine heat. I am thinking that it is not the neutral safety switch because I move shift lever to neutral which I thought bypasses neutral safety switch. I am looking for a start relay which shows up in a schematic of wiring. I checked all relays in the trunk on right side above the battery. Battery is located in right wheel well. This is a 1993 w140 300SD diesel. I believe there is another relay in the start circuit which is under the dashboard somewhere. I haven't located it yet. Next I plan to remove covers under the dash and search for any other relays that may cause problem. The starter always cranks with the remote starter cable. Amazingly everything else works on the car. It would be a wonderful car if I didn't have to raise the hood to start it all the time. Any help would be appreciated.