As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ENGINE APU FIRE SYS TEST (TASKCARD 74126002 STEP 2.E) NR 1 ENGINE IDG RESISTANCE BETWEEN PINS 2 AND 3 OF CONNECTOR DP 1206 MEASURED 69K OHMS IN THE "ON" POSITION (MINIMUM IS 230K OHMS). SUSPECT NR 1 GCU. NR 1 GCU REPLACED & INSTALLATION TEST CARRIED OUT SERVICEABLE IAW AMM 24-21-01-400-801. NR 1 ENG IDG RESISTANCE BETWEEN PINS 2 & 3 OF CONNECTOR DP1206 MEASURED SERVICEABLE AT 241 KOHMS (MIN. 230KOHMS) IAW ENG APU FIRE EXT SYS TEST TC 74126002 STEP 2E.