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2000 JIMMY with Auto 4WD actuator switch blinks once on starting

huronviewhuronview Member Posts: 1
edited April 2017 in GMC
Service 4WD light on
4WD actuator switch blinks when ignition moved to on.
Grounded #13 pin on OBD port, no trouble codes.
Replaced identical TCCM from EBay, same symptoms. I did this because TCCM determines which switch lights are activated.
Replaced actuator switch from junkyard, same symptoms.
Replaced vacuum hoses.
Bypassed solenoid on firewall, front axle actuator pulls, no problems shifting before lights went whacky.
Cleaned contacts on TCCM and actuator switch.
Disconnected the battery for 30 minutes
This model does not have the three vacuum lines at the transfer case.
Checked fuses and did the procedure with disconnecting the under hood fuses and switch on ignition 3 times
This leaves the vacuum solenoid, the front axle position switch, the position switch on the transfer case, the encoder motor, and the wire harness.
Do any of these stop the actuator switch from indicating the correct position? What next?
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