TM 9-2320-302-20 0010 00-17 Table 1. Electrical System Troubleshooting Procedures - Continued. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Instrument Wiring Circuits - Continued 6.  Axle Lock Indicator Light Does Not Operate - Continued. 3.    Disconnect lead 87 from axle lock   pressure   switch.   Check for continuity between lead 87 and ground. If no continuity is indicated, repair lead 87 (WP 0119 00). Ether Cold-Start Circuit Ether   Cold-start   Does   Not   Operate   When Container Has Ether. 1.    Check ether 10A fuse. Replace 10A fuse if defective (WP 0071 00). 2.    Remove ether 15A fuse. Check  for  +12  VDC  at  fuse connector   from   ignition   run power bus. If +12 VDC is present, go to step 3. If voltage is not present, repair circuit 18 (WP 0119 00). 3.    Disconnect     lead     166     from ether   switch.   Check   for   +12 VDC at lead 166. If +12 VDC is present, go to step 4. If voltage is not present, repair lead 166 (WP 0119 00). 4.    Disconnect lead 166A at cab/ chassis connection. Check for +12 VDC at lead 166A. If +12 VDC is present, go to step 5. If voltage is not present, repair lead 166A (WP 0119 00). 5.    Disconnect   lead   166A   from ether solenoid. Check for +12 VDC at lead 166A. If +12 VDC is present, go to step 6. If voltage is not present, repair lead 166A (WP 0119 00). 6.    Disconnect  ground  lead  from ether solenoid. Check for continuity between ground lead and ground. If continuity is indicated, replace ether  solenoid  (WP  0035  00).  If continuity is not indicated, repair ground lead (WP 0119 00). Air Dryer Heater Circuit Air Dryer Heater Does Not Operate. 1.    Check  reservoir  heater/power take-off 15A fuse. Replace 15A fuse if defective (WP 0071 00). 2.    Disconnect  lead  94  from  air dryer drain valve heater. Check for +12 VDC at lead 94. If +12 VDC is present, go to step 3. If voltage is not present, repair lead 94 (WP 0119 00). 3.    Disconnect  ground  lead  from air   dryer   drain   valve   heater. Check  for  continuity  between lead and ground. If continuity is indicated, replace air   dryer   drain   valve   heater.   If continuity is not indicated, repair ground lead (WP 0119 00). Standard Heater Circuits Heater Fan Does Not Operate at Any Speed. 1.    Check heater fan 30A fuse. Replace 30A fuse if defective (WP 0071 00). 2.    Check start/auxiliary 15A fuse. Replace 15A fuse if defective (WP 0071 00). 3.    Remove heater fan 30A fuse. Check for +12 VDC at lead 14 fuse connector. If +12 VDC is present, go to step 4. If voltage is not present, repair lead 14 to 12-volt constant power bus (WP 0119 00).