Rear diff locker relay operation help (1 Viewer)

[ariff]

So it appears I have a issue with the rear diff locker in my 93. I have been reading all the threads and I am prepared to disassemble and dig into the rear actuator, but before I do I want to check all the easy stuff first. Last night I checked all connections and wires everything looks good and I have continuity from the harness all the way up to the control box in the pass side kick panel. My position switch tests good as well. However when I attempt to engage the rear locker I just get the dreaded flashing lamp. I have tried driving in circles and cycling on and off with no help. Now when I engage the front I hear a relay click and bam they are engaged. However on the rear I never hear a relay click. My main question is to the front and rear share a relay? Do they use separate relays? Where are the relays located? I am thinking it is that little green box in the pass kick panel right below the control box? Just trying to think of things I can test before tearing into the actuator.. Also some posts have mentioned an inspection cover for the rear locker that can be removed easily to inspect the operation of the locker.. Any help on where that is located? Thanks for any tips form those of you that have crossed this bridge..

 

[lazy]

I believe they share an ECU. At least that is how the LX450's are setup and I was looking the wiring diagram last night. I don't know what circuitry is within the ECU, but since the ECU is is after the switch they either have a microprocessor or 2 relays within the magic box. You could test for continuity with switch on all the way to the fuse.

 

[ariff]

Circling back around to this again.. Any help on if I should always hear the relay click when engaging the locker.. Or if the actuator is seized up will the relay not click? thanks for any tips..

 

[nuclearlemon]

relay always clicked on mine regardless of whether or not the actuator was cycling, but don't assume that's normal

 

[LINUS]

I'm going to make a small assumption with you in KS.

Have you tried running the actuator itself w/ either a 9v battery, or similar?

Is there any signs of heavy corrosion on the actuator case?

All connectors on the rear pogtail are good (preferably greased) ?

-To the relay qestion - yes, I would swear I hear the relay cycle prior to the power going back, and ultimately the locker icon go steady. Then again, I know the relay kicks out too & maybe the front is cycling off / stay locked prior to the rear locking - since the front generally (always) kicks in before the rear if locking prior to needing.

 

[ariff]

Thanks for the replies.. I spent a few hrs doing some more testing and I am still not sure what may be the problem 100%.. Here s what I have done.. To answer the question above about corrosion. Yes there is surface rust on the out side on the guard and a bit on the actuator. I full well know that I may need to disassemble the actuator and rebuild it. i am just trying to check all the other moving parts before I do so.

1. I applied 9v to pins 2 and 3 and 3 and 2 and I could not hear the motor running at all.
2. Tapped on the actuator casing and repeated the 9v test no change.
3. Checked continuity from pins 2 and 3 to the plug at the dif locker ECU everything checks out here
4. Following the service manual I checked resistance between pins 1 and 3 on the diff lock ECU and I get an open reading when I am supposed to get less than 100 ohms. Checked the known good resistance on the front pins 5 and 7 and I get a good reading of less than 100 ohms.
5. Tried actuating the locker with the rear axle off the ground and turning the wheels by hand it never locks.
6. I still don't hear the relay clicking when trying to engage the rear.. But I do hear it click when engaging the fronts.
7. Checked and cleaned all connection everything looked good..
8. 30 Amp fuse checked and tested good for the lockers
9. Double checked and cleaned the lock position sensor and it is working as it should.

So my questions are this.. Are the relays located in the Diff Lock ECU? Or that green relay below them. When I removed the green relay to inspect it it said it was a light relay. I am guessing since I get no motor movement when applying 9v to pins 2 and 3 I am going to have to rebuild the actuator.. However I am still a bit concerned that I am not hearing the relay click when trying to lock the rear.. I tried checking for voltage at the rear when my son cycled the switch and I never saw 12v anywhere.. Can anyone tell me how I should be properly checking for voltage at the rear connection when the switch is cycled. Looking at the service manual did not really make much sense to me. Thanks for any help..

 

[ppc]

So my questions are this.. Are the relays located in the Diff Lock ECU? Or that green relay below them. When I removed the green relay to inspect it it said it was a light relay.

The relays are in the Diff Lock ECU. The green relay you are describing sounds like the timer module that controls the light around the ignition switch. I would need to study the FSM to answer your other questions as it could be a relay in the ECU or the actuator.

 

[ariff]

The relays are in the Diff Lock ECU. The green relay you are describing sounds like the timer module that controls the light around the ignition switch. I would need to study the FSM to answer your other questions as it could be a relay in the ECU or the actuator.

I was wondering if I could switch the pins 5 and 7 I believe for the front which is working with pins 1 and 3 at the ecu and see if the relay clicks then for the rear. I think that would tell me if the relay was bad? Any other ideas on how to test the relays in the ecu?