What was found
WHEN SELECTING THE NR 1 ENGINE ANTI-ICE SWITCH TO ON THE BLUE COWL VALVE OPEN LIGHT FLASHED BRIGHT BLUE MOMENTARILY AND THE AMBER TAI INDICATION ON THE NR 1 ENGINE ILLUMINATED. FOLLOWED QRH PROCEDURE AND CONCLUDED COWL ANTI-ICE VALVE FAILED CLOSED. WHEN CYCLING THE NR 1 ENGINE ANTI-ICE SWITCH TO OFF THE AMBER TAI INDICATION EXTINGUISHED AND THE BLUE COWL VALVE OPEN LIGHT ILLUMINATED BRIGHT FOR A SLIGHTLY LONGER PERIOD THEN EXTINGUISHED. GROUNDED-YES. DIVERSION TIME 90 MINUTES, PER B737-800 FIM 30-21 TASK 806. INITIAL EVALUATION SHOWS "TAI" INDICATOR AMBER DURING NR 1 ENGINE COWL ANTI ICE OPERATIONS TEST. FOUND PUSHED BACK PIN ON TAI VALVE CONNECTOR DP1303. REMOVED AND REPLACED HARNESS MW0313, IAW B737-800 AMM 71-51-03. REPAIR CONFIRMATION SUCCESSFUL, EEC CHECK GOOD, ACTUATORS CHECK GOOD PER FIM 30-21 TASK 806 AND AMM 71-51-03. GROUND VERIFICATION SUCCESSFUL.