Rear Diff Lock Actuator Control: Suspension AHC controller interaction (1 Viewer)

[Alex Neumann]

Hi There, I replaced my rear diff lock actuator (old one badly corroded and useless) after replacing the auto height control (AHC) suspension with "dumb" OME springs and shocks. When replacing suspension, we unplugged the plugs from the sockets on the suspension AHC control module under the dash.

The new rear diff lock actuator does not work (it does not engage and never has since fitting). Red light just flashes with no sign of engaging... Toyota spent a day investigating and tell me that all sensors and signals are working except for the "engage rear diff lock" signal. They tell me the rear diff lock control system needs a signal from the suspension AHC controller telling it that the suspension is not in the low position to allow the rear diff lock "engage" signal to be sent to the actuator. As the rear diff lock actuator is getting no signal from the suspension, it thinks the suspension is low and does not engage diff locker.

Has anyone on this forum had this issue before and got a quick and easy fix to implement so that I can revive my rear diff lock? Toyota won't touch it as it involves a modification to the suspension...

 

[Bama4door]

In the US, 98-99 land cruisers were the only years and model (not lx470) to get a rear locker from the factory. 98-99 land cruisers never came with AHC here. All year LX470's and then some Land Cruisers had AHC (05-07 I believe).

Anyways, one way you may get around it is to order the Slee Offroad CPU e-locker control box. This will bypass the OEM harness and ECU and allow you to lock the rear diff in high range too.

 

[flintknapper]

In the US, 98-99 land cruisers were the only years and model (not lx470) to get a rear locker from the factory. 98-99 land cruisers never came with AHC here. All year LX470's and then some Land Cruisers had AHC (05-07 I believe).

Anyways, one way you may get around it is to order the Slee Offroad CPU e-locker control box. This will bypass the OEM harness and ECU and allow you to lock the rear diff in high range too.

^^^^^ And then only as an option.

 

[Torontolaggars]

Interesting. I have the same problem with my 1999, LC100 - sold here in Sweden. I did an AHC delete and unplugged the lower plug from the suspension AHC control module under the dash (as recommended). I can't get my rear diff to lock, it´s just blinking... I was ready to buy a new actuator, but this thread makes me think I have the same problem as Alex Neumann.
Any tips how to fix my rear diff to engage?
Thanks Guys!

 

[Alex Neumann]

Hi there, my actuator started working on its own after investigating it for about 6 months. Not sure if it was seized, or whether I was just not spinning the jacked-up wheel far enough to allow it to engage. Turns out that the advice from Toyota was rubbish, their engineer cant read control drawings. I spent some time getting familiar with the control logic and there is no interaction from the AHC (or its sensors) to the rear diff lock. My rear diff lock red light still flashes when the lock is engaged which means that the sensor is not working right, but I am happy with this as I can clearly tell whether it is engaged or not, and I hardly ever use it anyway. I have checked the operation of the rear diff lock on a number of occasions since it mysteriously healed itself (by jacking up one rear and one front wheel and going through the centre and then rear diff lock process), and it has worked every time. Note that the rear diff lock does require significantly more "free-wheeling" to get the lock to activate, between 1/4 and a half wheel circumference turn before the lock actually clicks in after being "charged" by the actuator.

 

[diego355]

Just plug the module back and call it a day. I left mine in and i'm just waiting for the "off" annoying blinking light to burn out.
I don't really see the reasoning behind a locker actuator not engaging due to the AHC module but plug it itn and test.