I posted on this problem a while ago, but I can't find the thread.

The locking system on this car has never worked correctly. The remote works fine (at least until yesterday), but you cannot lock or unlock the car from the trunk or the driver's door. If the car was locked with the remote, you can unlock the driver's door, but the car won't start.

Last night the car would not unlock with the remote. No red or green light on the mirror when the button was pressed. No door lock/unlock. The car would turn over but not start, red and green lights flashed. Fortunately it did this in the driveway.

So today I verified that the remote was putting out a signal. I found the RCL N54/1 control module (behind the passenger air bag). I removed it and tested the harness for power and ground. While I was at it, I verified the signal from the driver's door lock - 0 v unlocked, 12 v locked. Then I reconnected the module to test if it was getting a signal from the remote receiver on the mirror. When I hit the remote button, I saw the voltage change like it's supposed to, and the doors locked. Hit the button again, and the green light blinked and the doors unlocked. A miracle!

So now the car locks and unlocks and starts for no reason other than I removed the control module and did some testing.

One other complication is that the PN on the module was 210 820 27 26, which is for a G-Wagon.

So, my question is, where to go from here? I am happy that the car is starting again, but it's not something I want to trust to chance. The way the testing went, I can't tell if the infrared receiver or the control module was at fault.

I would also like to get the car to unlock from the door. Is fact that that the control module was getting the correct signal from the door lock enough evidence to replace the control module (probably not inexpensive)?

Advice welcome!

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe