4wd ?

[windowman]

I have a 2003 envoy XL when truck is in 2wd indicater light is good.
When Awd is selected indicator light is on solid and awd seem to be working fine.
When 4WD HI or 4wd lo is selected you can hear motors and relays working and truck is locked in 4wd however the indicator light does not stop blinking.
Has anyone seen this and what may be the problem . Thanks

 

[windowman]

update we reset the control mod and light work good now however truck will not lock in 4wd hi or 4wdlo eventhough lights indicate it is locked in. A4wd works great. any help ??