Do you happen to remember what the ATA module looks like?

Is it fairly large? Does it have one, two or more connectors? Is it black? Any markings or numbers? Thanks.

The ATA module is about the size of a small textbook with a bulkhead connector. The part number on mine was A 124 820 19 89.

On sedans it may be located in the front passenger footwell near the firewall under the carpet.

question: starting what year do you need to jumper the relay? (i have a 1993) and i need to disable my alarm without disabling the car obviously

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1993 300E, 2.8 M104 .....

For those that may experience a similar problem, the following are the steps taken to remedy the issue.

The cause: a faulty driver's side door lock.

The problem: the door lock sensor was providing signal to the ATA (Anti-Theft Alarm) causing the alarm to be activated when the ingition switch was turned to the start position. Thus the ATA lockout was engaged and the car would not start.

The solution: diagnose the issue to determine what would be an appropriate plan to solve the problem. Since I had an idea that it stemmed from the driver's side door lock, I narrowed my search to disabling the ATA. I jumped the car using Arthur Dalton's X27 method. That gave me hope that I could rule out several other possible causes such as a weak battery, blown fuse or faulty NSS (Neutral Safety Switch). After reading numerous postings I found several posts about jumpering the K38 relay between pins 30 & 87. Posters Kestas and babymog helped me locate (located behind the instrument panel - there are also posts describing the tools and method for removing the instrument panel) and jump the relay appropriately so I was able to by-pass the ATA lock-out and start the car. But the ATA was still active and causing an audible alarm as well as a slow drain on the battery. So, I still needed to disable the ATA. Disabling the ATA was fairly simple. I knew where the ATA was located but I didn't know which module was the ATA. On my 1995 E320 Sedan it is # 126-820-24-26. Poster david s poole provided an earlier post providing this information. I removed both plugs to disable the ATA.

Now the car acts as it should, only without the Anti-Theft Alarm. The locks work and everything else seems normal. If anything acts up, I'll post a follow-up. I can suggest that to disable the ATA you will need to jumper the K38 relay otherwise the lock-out will keep you from being able to start your car. Also, have the code required for the radio handy as well. I hope this helps someone else and many thanks to those posts and posters that helped me. I have my car back and didn't pay the MB dealers for useless diagnostics and very expensive shop time.