1999 Holden Suburban Engaging Electronic 4WD

I am assuming that it is the same wiring as Chevrolet, but I am not sure. For starters, can you give me the wire colors on that front axle actuator connector, and I will compare them with the schematics I have available. I am showing brown(which should be power), black, gray with a black trace, and black with a white trace. If this is the same, it would be safe to assume that we have correct information.

Many thanks for your reply. The Plug on the front axle acyuator has four wires. The plug has five points set out like a five on a dice. The top right is Black.
The centre is Grey with a black line. The lower right is Brown ( which has power.) The lower left is Black with white line. The fifth point (top left ) is blank
Hope this helps. I look forward to your reply.

It looks like the schematic I can reference in North America, is the same layout as your vehicle. One other important thing to know, is this a manual(selectable), or automatic four wheel drive system. The light flashing is normal, it will flash until the front axle is engaged. For the selectable(NVG 243), you have a couple players involved. It shows power on the brown wire pin c, from the fuse, you already verified that. There is a transfer case switch, looks like it is mounted to the case, that has two wires going to it, gray with black, and black. More than likely it closes mechanically when the transfer case is in either 4WD range. It looks as though you should have power at that switch on pin c(GRY/BLK) in 4WD, and ground on pin c. The ground is the same ground you would have at your actuator pin e(BLK). When your actuator transitions to show engaged, power from the brown wire is routed internally to pin A(BLK/WHT) of the actuator, and this signal is grounded at the transfer case control module, this is probably what signals the switch that successful engagement has been achieved. You can eliminate the two wire switch on the transfer case by first checking for power on GRY/BLK, checking that ground is present on black, and bridging the two wire connector to substitute a closed switch. If this does not work, and you have good ground at that switch, and pin E of the actuator connector, backprobe pin A at the actuator. If you have no power at pin A, replace the actuator.