Center Differential Lock Not Working in Low (1 Viewer)

Jun 1, 2021
I’m gonna hijack this thread with an issue I’m having with my CDL. I have a 97, center diff lock button added by PO. And I can not get the cdl to do anything. The dash button used to work in either high or low so I know it used to work. Here’s what I’ve done to test it, used this thread for help and did all the tests.
- pulled cdl dash button from dash and tested continuity, it checked out.
- pulled relay from kick panel, tested continuity with and without 9-volt power. It checked out.
- tested all 3 switches on the tcase, they all checked out.
- tested ohms on the actuator and it checked out.
- hooked the actuator motor up to 9-volt power and it DID engage AND turned the lights on the dash, confirmed it locked by driving around, unlocked the cdl by reversing 9-volt power to the actuator motor.
- don’t know what else to test.

Pressing the cdl dash switch triggers the relay in the kick panel, I can hear it every time. But it does not engage the actuator. I also checked the 10amp gauge fuse and 30amp diff fuse. So I’m stumped. Any ideas out there? Everything seems to be working but there’s a lose somewhere from the relay to actuator motor.
Did you read CruiserDans response to the earlier post?
“when in low range the the shift points move up to a higher RPM. Very much like when you switch to the power mode. If the transmission shifts rapidly through the gears in low range the low 4 position circuit is not working.”
That means the low 4 position switch is sending a signal to the transmission ECU. This means the system is behaving as though pin 7 has been disconnected.
Jul 6, 2018
Brooklyn, NY
Yes, when shifting into 4low the transmission shift points change and it is indeed in low range.
When trans is in park and tcase in neutral the a/tp light comes on the dash. When the center diff switch in tcase is pressed in it triggers the cdl and abs lights on dash. When actuator motor was locked and unlocked with 9volt power the lights on dash came on and off as they should also.

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