W202 Alarm Gone Wild... Please help.
 

All, I have searched the forum without much luck. Our 1999 C230K's alarm system is acting screwy. When you push the lock button it turns all the inside lights on and they will not go off. The doors do lock. I found this out the hard way after leaving it locked in the garage for a few days and the battery died.

It has been doing this for about two weeks that I know of. But for the last few months up until this new behavior started, it would not flash the parking lights on lock or unlock, and the inside lights WOULD NOT come on when you opened a door or unlocked the car.

So it has been acting up for a little while. I hope its not some central lock module that costs a fortune, anyone know any info that could help? Its a big PITA to have to lock the doors with the remote with the drivers door open, manually turn off the lights and then close the drivers door without it being locked.

TIA for any help.

E. J.
2003 ML500
2000 A62.7T
1999 C230k

Sounds like the PSE (locking pump/ alarm module) has gone
bonkers. that could cause all of your symptoms you listed.
Good luck.

Thank you...
 

Any idea on cost for a new PSE and where I should look for a good deal? I am trying to sell the car now and just need it to work, but don't need new or dealer cost to replace.

Also, any idea where its located and how hard a swap would be on my own. I am pretty mechanical and do most work on my cars.

Thanks again.

E. J.

Finally took it to the dealer...
 

Turned out to be the proverbial 2 cent part. After switching to a new battery, I swapped out the PSE pump and that didn't fix it, so I took it in. 2 hour diagnostic and they found "open circuit on L/S Door. Replaced contact switch." Part number: 202 820 95 10

So I guess it was one of the door sensors that tells when the door is closed. Part was $9.19 and two hours labor was $189.80.

Thanks for the help.

E. J.

I was going to say it sounded like a door switch. 210's will do this as well if the dont know the door is shut.



Joe