TM 1-1520-238-T-4 6–78 Change 5 6–16. HOD XMN 1 READING – DISPLAYS 0 LB OIL PRESSURE 6–16 Tools: Nomenclature Part Number Tool Kit, Electrical SC518099CLA06 Repairer’s Multimeter, Digital AN/PSM-45 Personnel Required: 68X Armament/Electrical Systems Repairer References: TM 1-1520-238-23 TM 55-1500-323-24 TM 9-1230-476-20-2 Equipment Conditions: Ref Condition TM 1-1520-238-23 Access provisions – L60 fairing open WARNING Turn off power before detaching or attaching wires and connectors. High current 28 VDC or 115 VAC is present. Failure to do so could result in death or serious injury. NOTE If OIL PSI MAIN XMSN 1 indicator is also illuminated, troubleshoot Task 6–16.3 before proceeding. 1. Detach P579. Check for open between: P579–1 and P579–2, P579–1 and P579–3. Does open exist? YES Go to step 3. NO Go to step 2. 2. Check for short between: J579–1 and ground, J579–2 and ground, J579–3 and ground. Does short exist? YES Go to step 3. NO Go to step 4. 3. Locate open or short in wire harness between P579 and MT9. Can wire harness be repaired? YES Repair wiring (TM 55-1500-323-24). Go to paragraph 6–13. NO Replace MT9. Go to paragraph 6–13. 4. Reconnect P579. Detach P673. Check for open between: P673–95 and P673–94, P673–95 and P673–110, P673–95 and P673–111. Does open exist? YES Repair open wire between: P673–95 and J579–1, P673–94 and J579–3, P673–110 and J579–3, P673–111 and J579–2. Go to paragraph 6–13. NO Go to step 5. 5. Detach P579. Check for short between: P673–95 and ground, P673–94 and ground, P673–110 and ground, P673–111 and ground. Does short exist? YES Repair shorted wire between: P673–95 and J579–1, P673–94 and J579–3, P673–110 and J579–3, P673–111 and J579–2. Go to paragraph 6–13. NO Refer to TM 9-1230-476-20-2 to troubleshoot multiplex subsystem. END OF TASK