Rear Diff Lock Testing … Let’s Start with the Basics (3 Viewers)

[KellyC]

Hello All

1996 Factory locked FZJ80

My rear diff lock has gone into retirement and I’m trying to bring it back.

Front and center diffs both lock without issue. The dash light just blinks for the rear, and the diff does nothing. Both rear wheels off the ground at the same time … they spin freely, in opppsite directions.

Before opening it up, I want to rule out electrical options. I checked the fuse, it appears to be good.

Based on wiring diagrams, I checked for power, and even tried using a jumper, but had no success. But truth be told, I’m not sure the right procedure for this step. I’ve heard something about a 9V battery test, but don’t know what that’s about.

I have a volt meter and usually know how to use it if I know where to tap the probes.

With the ignition on and switch on, I checked for 12V power and found nothing on the GL, G, GB, and GY wires. Is this the correct spot to test? Would jumping 12V power to one of these activate a locker that is working properly?

Thanks for any help or tips!

 

[Tools R Us]

Most often it's the ground that closes the relay, comes from the position switch in the actuator. When the rear locker is switched on, do you hear the relay click in the passenger kick panel?

 

[KellyC]

Most often it's the ground that closes the relay, comes from the position switch in the actuator. When the rear locker is switched on, do you hear the relay click in the passenger kick panel?

Yes - there’s definitely a subtle click noise from the passenger side foot area when the switch is engaged.

 

[too tall]

I too am experiencing the same symptoms on my wife's 80 series right now. Was thinking about taking a look this afternoon. I'll be watching this thread. I will post if I learn anything.

 

[Tools R Us]

Yes - there’s definitely a subtle click noise from the passenger side foot area when the switch is engaged.

If the relay is clicking in, there should be power and ground output to the actuator motor. If this is true and the motor isn't running, then the motor is bound or bad. Normally they bind from condensation, corrosion, affecting the bearing and/or bushings. If it's bound, and power is applied for too long, there is the chance of burning out the motor. If there is power going to the motor and it isn't running, the repair is inside the actuator. Toyota considers the actuator a unit, not serviceable, have repaired many of them, but it's not without risk, there are no parts available for them from Toyota.

 

[Tools R Us]

...
With the ignition on and switch on, I checked for 12V power and found nothing on the GL, G, GB, and GY wires. Is this the correct spot to test? ...

Where did you do this test? If at the actuator plug and it is disconnected, the relay will not close, ground for that comes from the position switch in the actuator, so disconnected when that connection is unplugged. Best to test it at the relay box (Diff lock ECU) the connectors there are not weather protected, so can be back probed when connected.

 

[KellyC]

Bummer about the high likelihood of it being the motor. I guess wheeling with an open rear diff isn’t the worst thing in the world. At least until I can find some time to tear it apart and prove Toyota wrong about not servicing it.

 

[KellyC]

Is there a way to manually engage the rear diff lock short term? I could see just leaving it on all weekend during a wheeling trip, then disengage and buy me time to do the fix properly later.

 

[Tools R Us]

A couple of threads with info.
Rear Locking Dif Assembly Help
Rear e-locker does not engage

 

[KellyC]

A couple of threads with info.
Rear Locking Dif Assembly Help
Rear e-locker does not engage

Thank you! Very helpful!

I searched through and read a lot of posts, but somehow didn’t find these.

This helps a lot!