You need to understand how they work , do you know about automotive electronic controls ? Your switches are just inputs to the BCM - body control module !
Door Locks Power and Ground
For door lock operation, the IP Fuse Block supplies battery positive voltage, through the 15 amp DR LK/TRUNK fuse, to the BCM. The BCM uses this circuit exclusively to apply power to the door lock actuators. The BCM is also supplied a ground circuit, which it uses exclusively to ground the door lock actuators. When a door lock is pulsed, the BCM internally connects these two circuits to the appropriate lock and unlock control circuits to actuate the locking or unlocking functions.
When diagnosing door lock malfunctions, these circuits must not be confused with the other battery voltage and ground circuits of the BCM. The appropriate wiring schematic must be used to locate the correct circuits. Failure to identify the correct battery voltage and ground circuits of the BCM during diagnosis of door lock concerns may result in misdiagnosis and unneccessary parts replacement.
Passenger Door Unlock Operation
When the BCM detects a transition of either of the door lock switches to the Unlock position, it switches the door lock actuator unlock control circuits to voltage. Since the door lock actuator lock control circuit is at ground potential within the BCM, the passenger door lock actuators transition to the Unlock position.
The door lock actuator unlock control circuits are dedicated control circuits used only for the passenger door lock actuators. This is done so that the driver door may be unlocked individually before unlocking the passenger doors using a keyless entry transmitter or an automatic door unlock function, if programmed. When the keyless entry transmitter is used to unlock the passenger doors, the BCM requires a repeated unlock command before it performs the unlock function. However, when the unlock input is from a door lock switch, a single unlock command is all that is required to unlock all doors.
How to test computer controlled door locks
I always use a high-quality lubricant for the appropriate situation -- no fish oil in use here. I maintain this car in tip-top condition but will re-oil that specific lock mechanism.
My rear door on my 2002 ML500 will open a crack so it is the locking mechanism at the hindge that is not releasing. I have pulled pretty darned ******* it, but I'm fearful it may break something if I pull harder. Now what?
rear door not opening ml500 model 2002. need help how to open it manually
×