Power Locks not working. Location of Door Lock ECU? (1 Viewer)
- Thread starter tony
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I just looked through my FSM ('01 LX470) and there are two distinct electrical paths for manually locking/unlocking your doors versus using the key remote. See below:
MANUAL UNLOCK OPERATION
When the door lock control SW of the driver or front passenger door is pressed to unlock side, a signal is input to the
instrument ECU TERMINAL DMU, and TERMINAL PMU respectively. Then the current flows from the POWER fuse to D/L
(U) relay (Coil side) to instrument ECU TERMINAL DURY to TERMINAL GND1 to GROUND, and turns on the D/L (U) relay
and D/L (DU) relay. At the same time, the current flows from the POWER fuse to D/L (U) relay, D/L (DU) relay TERMINAL 5
to TERMINAL 3 to door lock motor and back door lock motor to D/L (L) relay TERMINAL 3 to TERMINAL 4 to GROUND, and
unlocks the door.When the door lock control SW of the driver or front passenger door is pressed to unlock side, a signal is input to the
instrument ECU TERMINAL DMU, and TERMINAL PMU respectively. Then the current flows from the POWER fuse to D/L
(U) relay (Coil side) to instrument ECU TERMINAL DURY to TERMINAL GND1 to GROUND, and turns on the D/L (U) relay
and D/L (DU) relay. At the same time, the current flows from the POWER fuse to D/L (U) relay, D/L (DU) relay TERMINAL 5
to TERMINAL 3 to door lock motor and back door lock motor to D/L (L) relay TERMINAL 3 to TERMINAL 4 to GROUND, and
DOOR KEY UNLOCK OPERATION
When the door is unlocked once by the ignition key from the driver side, a signal is input from door key lock and unlock
SW LH to instrument ECU TERMINAL DKU. As a result, the instrument ECU operates and the current flows from POWER
fuse to D/L (DU) relay (Coil side) to instrument ECU TERMINAL DDRY to TERMINAL GND1 to GROUND, and turns on
the D/L (DU) relay. At the same time, the current flows from the POWER fuse to D/L (DU) relay TERMINAL 5 to
TERMINAL 3 to door lock motor front LH to D/L (L) relay TERMINAL 3 to TERMINAL 4 to GROUND, and unlocks the
driver door only. Accordingly, if the second unlock operation is made within 3 seconds , a signal is input to instrument ECU TERMINAL DKU, and the current flows as manual unlock operation, and unlocks all the doors.
When the door is unlocked once by the ignition key from the driver side, a signal is input from door key lock and unlock
SW LH to instrument ECU TERMINAL DKU. As a result, the instrument ECU operates and the current flows from POWER
fuse to D/L (DU) relay (Coil side) to instrument ECU TERMINAL DDRY to TERMINAL GND1 to GROUND, and turns on
the D/L (DU) relay. At the same time, the current flows from the POWER fuse to D/L (DU) relay TERMINAL 5 to
TERMINAL 3 to door lock motor front LH to D/L (L) relay TERMINAL 3 to TERMINAL 4 to GROUND, and unlocks the
driver door only. Accordingly, if the second unlock operation is made within 3 seconds , a signal is input to instrument ECU TERMINAL DKU, and the current flows as manual unlock operation, and unlocks all the doors.
Assuming the obvious....that both drivers and passenger side switches did not go bad at the same time, it looks like the culprit could be the Instrument ECU or respective terminals / relays.
If you have the full FSM, you could just trace back from the first common point (TERMINAL GND1) and being your testing.
Good luck.
Here's the location of the instrument ECU:
Here's the wiring diagram:
Here's the wiring diagram:
