Table 9-1. Compressed Air and Brake System Troubleshooting Procedures (Continued).
TEST OR INSPECTION.
19. INTERAXLE DIFFERENTIAL LOCKUP INOPERATIVE:
Disconnect air lines at rear axle; then engage lockup control valve on instrument panel. Check for
air pressure at rear axle. No air indicates clogged lines or defective control valve.
Replace clogged lines.
Replace defective control valve (para 9-44).
If air controls are working normally, refer problem to Direct Support