#Bmw e46 automatic transmission problems how to

Even if the car is neutral, the clutch is engaged and inoperable by the carвЂ™s computers. When the pump fails and the aforementioned fuse is blown, the on-board computers that monitor and control the pump are no longer able to communicate with it and have no way to вЂњknowвЂќ what gear the vehicle is in. How does a failed SMG pump cause the car to not start? Left: Blown 40 Amp SMG pump fuse, Right: SMG pump 40 Amp fuse location on a 2003 (E46) BMW M3 The SMG pump (pictured below) is similar to an ABS pump in both appearance and function, but controls the hydraulic pressures in the transmission and not the brake system. When the M3 arrived at the shop, we hooked it up to our computer diagnostics scan tool and found a DTC, or вЂњdiagnostic trouble code, вЂњ indicating a fault with the Park/Neutral solenoid, which is an integrated component on the SMG hydraulic pump assembly.

#Bmw e46 automatic transmission problems how to

Symptoms and Diagnosis: How to know when an SMG pump has failed and needs to be replaced. Instead, the clutch is controlled electronically by a computer and actuated by hydraulics. You still change gear much like you would in a conventional standard by using a вЂњstickвЂќ of sorts (or by paddles mounted just behind the steering wheel), but there is no clutch pedal. Just to clarify for those who arenвЂ™t familiar with BMWвЂ™s SMG transmission, the simplest way to explain it is that itвЂ™s neither a conventional вЂњmanualвЂќ nor вЂњautomaticвЂќ transmission, but more like a combination of the two. There are many more common causes for a no start вЂ“ like a dead battery, worn out starter, faulty brake pedal switch, etc.- and after checking the usual suspects and not finding the problem, he had the car towed over to our shop. When our customer got into his E46 M3 recently and found that it wouldnвЂ™t start, a transmission problem was the last thing he suspected to be the culprit.