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Billy
Billy, Trainer/Master tech.
Category: Mercedes
Satisfied Customers: 3498
Experience:  Trainer 8+ years, Master tech. 10+ years, SAE member
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Slk 230: I did a pre-emptive switch of the k40 relay .....

Customer Question

I did a pre-emptive switch of the k40 relay ..... But when I went to restart the car it fires up and immediately stalls.
Put the old k40 back in and have same problem. Battery was disconnected when I changed the units.
What's causing the stalling?
Submitted: 1 year ago.
Category: Mercedes
Customer: replied 1 year ago.
Also tried different ignition key, as well as putting ignition switch into position 2 for 5 minutes.... Neither made any difference.
Expert:  Billy replied 1 year ago.
Hello and Welcome! I'm Billy and i will assist you with this. Feel free to ask, if further info is needed.
I would need more details to try and pinpoint the problem:
- the engine fires up (runs) for a few seconds and then stalls?
- did you check for any blown fuses?
- do you have any warning lights on or blinking?
- did you check using a scan tool for any fault codes?
- did you try cleaning the throttle body?
Customer: replied 1 year ago.
The battery had been disconnected for a week prior to swapping the K40.There are no warning lights and I've not encountered any blown fuses. Have not run any scans. Vehicle was running ok prior to disconnecting battery for the week.MAF is clean.
Expert:  Billy replied 1 year ago.
Hello,
I'm referring to the throttle body (where the butterfly valve is, not the MAF.
This needs checking and cleaning, the blown fuses need replacing. And if the problem persists, you need to check using a scan tool, retrieve the fault codes so we can proceed accordingly.
I will be waiting for your findings.
Regards,
Billy
Customer: replied 1 year ago.
Please note that the car was running fine prior to the K40 switch. prior to the K40 switch the battery was disconnected for one week. The throttle body is clean.No fuses blown.Vehicle starts perfectly then stalls in 2 seconds, almost as if this is an anti-theft measure of cutting fuel.
Expert:  Billy replied 1 year ago.
Hello again,
This usually is caused by the throttle body (needing cleaning or reprogramming). The original immobilizer would prevent engine starting on mercedes.
The fuel pump relay was already checked (k40), and sometimes installing a new battery would cause some fuses blowing...
If you had ignition off while installing the battery, then the next step would be connecting a scan tool to see if any codes are stored, program the throttle valve.
Get back to me with your findings, so we proceed accordingly.
Regards,
Billy
Customer: replied 1 year ago.
The ignition key remote does not work. Given the disconnected battery could this keep the immobilizer from recognizing the key? Or does the immobilizer only work off the mechanical key ?Thanks
Expert:  Billy replied 1 year ago.
Hello again,
My apologies for the delay, thank you for your patience.
The immobilizer should still recognize the key, even after a battery disconnection. The immobilizer works off a chip inside the key. The immobilizer function and the remote locking/unlocking function, are two separate systems (although both are within the key). If you're vehicle was manufactured prior to 05/1997 then you should be able to program the central locking (remote) function:
Programming
→05/97
When
Remote control buttons operated repeatedly while vehicle out of range and system becomes inoperative.
Remote control batteries not replaced within 1 minute.
Remote control batteries completely discharged.
Remote control added or replaced.
How
Type 1:
Point remote control at receiver (located in driver's door handle or next to boot lock button).
Press lock/unlock button.
Within 30 seconds manually lock or unlock vehicle using the passenger's door lock or boot lock.
Type 2:
Point remote control at receiver (located in driver's door handle or next to boot lock button).
Press lock/unlock button.
Switch ignition ON within 30 seconds.
Type 3:
Point remote control at receiver (located in interior mirror).
Press lock/unlock button twice.
Turn ignition switch to position II within 30 seconds.
06/97→
When
Remote control(s) added or replaced.
System malfunction.
How
Remote controls can only be programmed using diagnostic equipment.
Kindly try this, and get back to me with your findings, so we proceed accordingly with the diagnostics, till we pinpoint the culprit.
Regards,
Billy