Blinking 4wd lights

[fierohink2]

I have a '99 Limited A/T with M/M transfer case and e-locker with 121k miles. For about two years or so I've had a random blink of the 4 green 4wd lights while driving in 2wd mode. About a year ago, maybe less, the 4wd quit working and would not go into 4x4 mode either by pressing the M/M switch or shifting the j-shift lever into 4HI.

I thought it was going to be the switch on the front diff that seems to be a common failure. I have tested it, get good continuation for open and closed, but did not improve the function of the ADD.

Using the shifter does engage the front driveshaft. So I know the transfer case works.

I can apply vacuum to the two ports on the front diff actuator and get it to engage and disengage. So I think that actuator works.

I cleaned and tested the 2 switches on the transfer case actuator and they now have good open and closed continuity.

I have used information from another thread provided by [MENTION=10169]TheDurk[/MENTION] to do a series of tests at the F7 connection at the 4wd ECU.

I have also tested with a multimeter to find a functioning fuse.

I need help interpreting the data I have at this point. And getting direction as to what to check next.

 

[fierohink2]

damn photobucket

 

[fierohink2]

This is the results of testing connection F7 at the 4wd ECU

 

[fierohink2]

It's Fixed

omg omg omg

After trying the relay test to get the actuator on the transfer case to do something, anything and failing, I shopped eBay for a used transfer case and succumb to the realization that my actuator was fried.

Since I had nothing to lose. I took the cover off the motor on the actuator. I found the original grease all dried and caked up. The pads of the contacts on the cover were tarnished green.

I cleaned everything up, sprayed with contact cleaner, polished the contacts with emery cloth and reassembled.

Push the button and..............Kah-clunk......... the 4wd lights blink and the go solid. Backing out of my driveway I can feel the front push and grab from engagement.

Thank you to everyone that has write-ups, threads, pictures, etc.

A big thanks to [MENTION=10169]TheDurk[/MENTION] for uploading EWD pictures here and on yotatech.