Managed to get my front and rear diff locks working today. Only had the truck almost a year, but had resigned to the fact that it would be a big job to tackle, so hadn't bothered until now.
My front and rear diff-lock switch was not functioning, nothing on the dash was lighting up. So having read on another thread about a similar issue, I dropped the dash fascia off to check the switch and the switch was unplugged! It seems the wiring here doesn't have any slack, so presumably when the last person to take the dash apart wasn't fully awake!
Only a 15 min job to get re-connected, and I now have working front and rear-diffs! Both motors wurr away when fired, the rear diff seems to take longer to engage - although I was in a straight line Now just need to fit a CDL switch and remove the transfer box plug
No idea how long its been like that for the previous owner, but shows the diff locks can be quite reliable - although the truck has been used mainly on-road.
My front and rear diff-lock switch was not functioning, nothing on the dash was lighting up. So having read on another thread about a similar issue, I dropped the dash fascia off to check the switch and the switch was unplugged! It seems the wiring here doesn't have any slack, so presumably when the last person to take the dash apart wasn't fully awake!
Only a 15 min job to get re-connected, and I now have working front and rear-diffs! Both motors wurr away when fired, the rear diff seems to take longer to engage - although I was in a straight line Now just need to fit a CDL switch and remove the transfer box plug

No idea how long its been like that for the previous owner, but shows the diff locks can be quite reliable - although the truck has been used mainly on-road.