What was found
OVERHEAT/FIRE TEST, ENG 1 OVERHEAT DOES NOT LIGHT UP. WHEN SWITCH PUT ON A OR B IT WORKS FOR BOTH. ON NORMAL, THE LIGHT DOES NOT COME ON. FIRE HANDLE ALSO DOES NOT LIGHT UP. WHEN OVHT DETECT SWITCH IS IN POSITION B, ENG 1 FIRE TEST WORKS IMMEDIATELY WITHOUT THE TEST SWITCH AND APU/ENG 2 DON`T TURN ON AT ALL. GROUNDED - YES. FOUND FIRE DETECTOR HARNESS MW0326 CHAFFING AND SHORTING AGAINST A CLAMP. REMOVED & REPLACED HARNESS, REF B737-900 AMM 26-11-02-400-802. ACCOMPLISHED ENGINE FIRE DETECTION OPERATIONAL TEST, REF AMM 26-11-00-710-801. OPS CK GOOD, GROUND VERIFICATION SUCCESSFUL.