TM 10-3930-669-10 Table 3-2.  Operator Troubleshooting Procedures - CONT. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION ELECTRICAL SYSTEM (CONT) 2. GLOW PLUG INDICATOR DOES NOT OPERATE. Step 1.  Check MAIN POWER switch position. If MAIN POWER switch is not in the ON position, set switch to ON position. If MAIN POWER switch is in the ON position, go to step 2. Step 2.  Depress glow plug button for 10 seconds and check glow plug indicator. If glow plug indicator light does not operate, notify Unit Maintenance. TRANSMISSION 1. TRANSMISSION SLIPS OR WILL NOT ENGAGE IN FORWARD. Step 1.  Check transmission oil level (Para 3-12). If transmission oil level is low, add oil (Para 3-12). If transmission oil level is OK, go to step 2. Step 2.  Check transmission in reverse. If transmission will not engage in reverse, go to step 3. If transmission will engage in reverse, notify Unit Maintenance. Step 3.  Set transmission speed switch to high position and check transmission high gear indicator light. If transmission high gear indicator light does not operate, power to transmission electrical system is faulty.  Notify Unit Maintenance. If transmission high gear indicator light operates, transmission is faulty.  Notify Unit Maintenance. 3-7