my fwd indicator light flashes four to six times on occasion and has ceased to engage. any ideas where to start troubleshooting? also I'm getting a 401 code- lack of flow in the egr-, whats thew more likely culprit, the valve or the sensor? any testing proceedures? Thanks John.

 

I'd say the 401 code is most likely a DPFE sensor problem, but you should also check the hoses and tube to make sure ther aren't any resterictions. See: The Ford DPFE/EGR System

On your '99, the 4WD system will set trouble codes that can be retrieved in order to help diagnose and treat the problem. The flashing light indicates that some codes are probably pending and/or stored. The bad news is that the codes cannot be retrieved without a special scanner that is only available at Ford dealers and professional repair shops.

You ought to check all the fuses relating to the 4WD system and transfer case, in any event.