Ok I have done some searching. I am new to the toyota 4wd. From my searching I have gathered that I have the ADD system on my 89 p/u SR5. No manual locks. Anyways, When i shifted into 4L or 4H before the light on the dash lite up(doesnt now). It looks like there is vaccum lines going to an acuator on the front diff. I have not been able to get all 4 wheels off the ground yet to see if the front wheels are spinning. I am in the process of trying to get manual hubs to install and was wondering if I am troubleshooting this problem wrong.
Does this make sense?
Basically what I am asking is how to check the ADD system?
Also from what I have read the manual hub swap is a straight forward bolt on correct?

 

All about ADD troubleshooting:
http://toyota.off-road.com/toyota/ar....jsp?id=399612

 

thanks bro that will help me out alot.......thanks for the quick response too.

 

Check your vaccum lines going to the actuator try pluging one of them up.