Liftgate fault tracing

[Chassis]

On my RX 450h 2009 the liftgate has stopped working. Before it gave up I could reset it by disconnecting the Battery but now it's dead, full time. Before I replace the motor/ECU I intend to check the remaining system so I have removed the unit to get access to the 26 pin connector, wire side. There are 12.7V on pin10 and pin12 and even on pin8 when ignition is on. So far so good.

Anyone knows how the cooperation between latch motor and lift motor assy works? Guess that the lift motor ECU knows the state of the latch (apart from ability to operate it). How can I test the latch from the 26-pin? 

Next thing to test is the two sensors, left/right "POWER BACK DOOR SENSOR ASSEMBLY" in the diagram? Where are they in the car? What do the do? How can I test? 

In the diagram there is a "POWER BACK DOOR MAIN SWITCH". Is that the one in the glove box?

Has anyone tried to power up the lift_motor/ECU assy on the bench in order to fault trace it? According to the diagram it might be possible to test it with the latch unit connected and simulate the two sensors, though there are two CAN lines (pin5 and pin6) that might have some influence. 

If I have to replace the lift motor/ECU assembly, can I just do so without any programming?

Thanks in advance for all contributions😊

Per 

 

[ColinBarber]

33 minutes ago, Chassis said:

though there are two CAN lines (pin5 and pin6) that might have some influence. 

At least one person who had a similar fault checked the CAN modules and the power back door module was offline - don't know whether the whole module was dead or the fault is related to the CAN bus electronics within it.

 

34 minutes ago, Chassis said:

If I have to replace the lift motor/ECU assembly, can I just do so without any programming?

Yes.

[ColinBarber]

49 minutes ago, Chassis said:

In the diagram there is a "POWER BACK DOOR MAIN SWITCH". Is that the one in the glove box?

Yes

[Chassis]

Need some understanding how it all works before I replace the main unit (motor/ECU assembly). The main unit ECU is obviously the brain. Then there are the lock/latch unit and the two side sensors (POWER BACK DOOR SENSOR ASSY, Left and right in the diagram). What type of sensor is that? No visible moving parts! I measure 980 Ohm over the terminals on each of them (no polarity) but I haven't found out a way to close the "switch". Magnetic? Position? Proximity? Are there other input (i.e. Switches/sensors in the lock/latch assembly) to the ECU that I can simulate to force operation? Want to exclude all other possible faults before the "heavy" replacement. Can I measure/do anything on the 26p connector to isolate the problem? The motor/ECU assy looks like new, no corrosion, no nothing, even the PCB looks new. Any input is deeply appreciated. Thx in advance:)

[Chassis]

ECU in the lift motor assy was the culprit. Got hold of one on eBay. Thanks everyone for the contribution😊

[Madsod]

Hi Per,

There have a number of members on here with the power back failing, the only solution I can see so far is Herbie kindly sending out emails/messages to people who have a problem which, without being disrespectful to Herbie, I’m unsure of the success rate of…..but you clearly seem to have found a solution and I wondered if you could provide a little more detail in respect of the fix, how you tested the mechanism, part purchased etc so other people, with aging 450H’s, could use your expertise to potentially fix their power back door?

I know it’s a bit of an ask but I’m sure other members would really appreciate it if you had to the time to put it together for us.

 

Kind Regards

Kev

[brendangeorge]

On 4/19/2024 at 8:15 AM, Chassis said:

On my RX 450h 2009 the liftgate has stopped working. Before it gave up I could reset it by disconnecting the battery but now it's dead, full time. Before I replace the motor/ECU I intend to check the remaining system so I have removed the unit to get access to the 26 pin connector, wire side. There are 12.7V on pin10 and pin12 and even on pin8 when ignition is on. So far so good.

Anyone knows how the cooperation between latch motor and lift motor assy works? Guess that the lift motor ECU knows the state of the latch (apart from ability to operate it). How can I test the latch from the 26-pin? 

Next thing to test is the two sensors, left/right "POWER BACK DOOR SENSOR ASSEMBLY" in the diagram? Where are they in the car? What do the do? How can I test? 

In the diagram there is a "POWER BACK DOOR MAIN SWITCH". Is that the one in the glove box?

Has anyone tried to power up the lift_motor/ECU assy on the bench in order to fault trace it? According to the diagram it might be possible to test it with the latch unit connected and simulate the two sensors, though there are two CAN lines (pin5 and pin6) that might have some influence. 

If I have to replace the lift motor/ECU assembly, can I just do so without any programming?

Thanks in advance for all contributions😊

Per 

 

I sourced a new assembly from Rock Auto for £400 delivered took - 3 days from the US.