CDL locked regardless of 4 hi/low, how to test signal to actuator? (1 Viewer)

[hakalugi]

In stock form my 1993 had the dash-CDL button added, and the 7 pin mod. When I got my Aqualu tub swapped truck back from Redline, the center diff was permalocked and they said it was a bad actuator or something mechanical. They discovered it right as my transport was scheduled so it came back to me like this.

I've had 2 other shops look at it and they couldn't figure it out and they're not sure the signal is getting to the actuator... I still have a dash mounted CDL button, fwiw.

So taking a step back, anyone have any advice on how how to test if the CDL's actuator is getting the proper signal without dropping the center diff?

Thanks,

 

[hakalugi]

So I've been you-tub'ing and seem have come to some tentative conclusions:

* the sensor line ("is my CDL locked") seems to be about lighting-up the CDL icon in the dash, not about any 'feedback' to the ECU(s) to behave differently.... (this from people disconnecting it to clean contacts/replacing the sensor and the CDL functinality being unchagned, just no light in the dash)
* the 'engage CDL' function appears to be an electrical signal/input only, regardless of the position of the shifter fork physically going into 4-low vs. 4-high (if not, the 7 pin mod wouldn't work) - ?

I no longer have a stock dash, I have a dakota digital 40 series dash, so the 'light up the dash lights' doesn't matter to me. And only "sending the right signal to the CDL actuator" is what matters to me. per page 910-911 of this: 1994-FZJ80-FSM.pdf | Powered by Box - https://app.box.com/s/dbsqb7zphoadoe0ka33rpan8b7e80ywr the "diff lock ecu" does take input ensuring you're not at speed when allowed to engage the CDL... but presumably, If I'm willing to be the gatekeeper for that decision, maybe my plan-B** is to bypass that ECU and send the needed DC signal to the CDL itself to 'actuate'. But oddly, page 912 shows actuators for front and rear, but not for the center...

maybe i'm staying locked b/c the speed indicator is not working and the vehicle doesn't see me going below xx mph to disengage...

** about that plan B: using my dash mounted CDL to simply send the needed battery voltage signals to the CDL actuator to engage or not manually - thoughts on this?

 

[landcrshr]

So I've been you-tub'ing and seem have come to some tentative conclusions:

* the sensor line ("is my CDL locked") seems to be about lighting-up the CDL icon in the dash, not about any 'feedback' to the ECU(s) to behave differently.... (this from people disconnecting it to clean contacts/replacing the sensor and the CDL functinality being unchagned, just no light in the dash)
* the 'engage CDL' function appears to be an electrical signal/input only, regardless of the position of the shifter fork physically going into 4-low vs. 4-high (if not, the 7 pin mod wouldn't work) - ?

I no longer have a stock dash, I have a dakota digital 40 series dash, so the 'light up the dash lights' doesn't matter to me. And only "sending the right signal to the CDL actuator" is what matters to me. per page 910-911 of this: 1994-FZJ80-FSM.pdf | Powered by Box - https://app.box.com/s/dbsqb7zphoadoe0ka33rpan8b7e80ywr the "diff lock ecu" does take input ensuring you're not at speed when allowed to engage the CDL... but presumably, If I'm willing to be the gatekeeper for that decision, maybe my plan-B** is to bypass that ECU and send the needed DC signal to the CDL itself to 'actuate'. But oddly, page 912 shows actuators for front and rear, but not for the center...

maybe i'm staying locked b/c the speed indicator is not working and the vehicle doesn't see me going below xx mph to disengage...

** about that plan B: using my dash mounted CDL to simply send the needed battery voltage signals to the CDL actuator to engage or not manually - thoughts on this?

The diagram you referenced is misleading.
The diff-lock ECU does NOT control the CDL. The CDL actuator is controlled by the CDL RELAY. In stock form the relay is located in the driver footwell and you should hear it click whenever the dash mounted CDL switch is pressed in/out. If you're not hearing the relay, you will need to troubleshoot the wiring associated with the relay, especially the wiring between the switch and the relay.
The CDL relay also needs input from the actuator limit sensors.

HTH

 

[hakalugi]

Ok thanks. That assembly is now up under my dash- I’ll check for relay sounds…

 

[jonheld]

You can also check the actuator motor for rotation in both directions with a 9 volt battery across pins 2-3.

 

[hakalugi]

No clicking in my left footwell when I engage my CDL nor my transfer case. I found an ebay replacement part and swapped it, and it made no difference. i bought low range reduction gears, so i'll be dropping the t-case later this month and will try to actuate using the 9v battery trick and also ensure the wiring from t-case back up isn't damaged.