antarr

I have a 2001 Mercedes E430. I'm having problems getting it to start. Usually, I have to get a boost to get it to start. But I just discovered that disconnecting the battery completely gets it to start as well. After disconnecting the battery it will run fine for a few days. Also, I hear a single click sometimes when it doesn't start.

cMazara

What do you mean as to disconnecting the battery? How do you start it without a battery?

the boost issue must be an electrical leak, there's something drawing power and draining your battery overnight.

antarr

I disconnect the battery at both posts then reconnect it, and the car starts. There is no drain on the battery it is fully charged.

Beezalino

Correct. I'm looking for effective trouble shooting steps?

bicylindrico

This reminds me of al old SLK320 I purchased many years ago. The issue was that the engine would not crank to start the car unless the battery was disconnected and then reconnected. It would then crank and start until the ME module 'went to sleep' on the CAN line after the car was shut off. It would then need to be power cycled to start again. It looked to be some issue with DAS authorization within the ME module itself which is why she sold it cheap. I just removed the circuit 30 power to the module and connected it together with the 87 circuit at the K40 relay. This essentially 'power cycled' the module with each key cycle. She started every time then.

bicylindrico

The K40 relay module were very prone to intermittent starting/running issues. You may want to try taking it loose with the engine running at moving it around or tapping on it. Sometimes you can do this with just the key in the on position and you can hear engine components clicking while shaking the K40