BMW E46 318i only Crank! Won't start!

January 04, 2018 Harith Salwathura

Here I'm writing up my story of my car which hasn't been started for almost 5 months once I changed the rocker cover gasket and battery. Literally what happened is I have removed the rocker cover gasket to replace and also the battery. So once I remove the rocker cover gasket I had to remove the battery and left it for few weeks till I receive the ordered parts. After all I replaced the gasket and the battery car won't even crank. When I crank the engine it was just only clicking not crank the engine anymore. I was doing research for some time in google and find out BMW Battery Safety Terminal (BST) it is just located in end of the battery Positive terminal. Just like a small module check attached photo.

What is this BST?

The BMW Battery Safety Terminal (BST) is used to reduce the risk of a short circuit to the B+ terminal of the battery in the event of an accident, as a result of a short circuit on the cable running from the B+ terminal of the battery to the Starter & Alternator (an unfused/unprotected circuit).


Depending on the severity of an accident incurred, the MRS control module will provide a signal to the BST which will disconnect the B+ cable going to the Starter & Alternator. In the event that the BST is activated, power will continue to be supplied to the rear power distribution box (a fused/protected power distributor) to allow activation of all other vehicle systems (such as hazard lights, power-locks, power-windows, Engine Electronics etc.).

BMW Battery Safety Cable Disconnection Sequence

Because the battery cables are divided up in the rear distribution box, the rest of the vehicle electrical system remains operational when the safety battery terminal is triggered as long as none of the main fuses disconnect the circuit as the result of a short circuit. This ensures that all the important functions, such as e.g. hazard warning flashers, telephone, remain operational. Fixed with most of these models. E36, E39, E46, E60, E61, E63, E64, E65, E66, E67, E90, E91, E92, E93, F01, F10, F12

Ok!! Back in the story, I don't know why the BST was activated and disconnected from the main +12 line to the car. How ever I managed to fix the issue using a hammer and plier.

Image result for bmw e46 bst

I hit to the terminal end with the hammer when I hold the other end with the plier, so the terminal got a tight connection once after few hits. Just tried crank the engine after fix the terminals to battery. Wonderful and car cranks!!! But won't start!! tried a lot times CRANKS! BUT NO START!! Really get pissed after all!! 

 Story to be continued with much more BMW crazy interesting stuff!! :D