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Starter wiring questions

Posted: Mon Mar 09, 2026 7:32 pm
by jeepjones03a3
I replaced my starter on my ‘83 E21, and got a new Bosch Sr40x. I’m somewhat confused on how to wire it correctly as the new starter has 3 spade posts as opposed to the old ones 2. On top of that I have not been able to find and photos with good enough quality to see if there are markings differentiating between them. I also have not been able to find a diagram of said new starter anywhere.

I am currently trying to hook up a workaround starting solution because my ignition switch is bad. I am essentially hooking up a remote starter switch as a secondary starting mechanism until I either get a full push start assembly or a new ignition switch.
Any advice is greatly welcome.

Re: Starter wiring questions

Posted: Tue Mar 10, 2026 10:26 pm
by Jeroen
I tried a Bosch manual but it only said electrical connection :hammer

Below diagram may help, no 50 - ignition wire is in between the threaded bolts next to the partition. The bottom threaded bolt connects the starter motor to the start solenoid, the top threaded bolt has the alternator + wire and the battery post + wire.
The other male spade terminal is not used on later models, its a connector to a power resistor in case of contact points.

Start Sol_1980.jpg
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