Diagnostic tools test vehicle systems and highlight areas needing repair. Digital diagnostic tools identify automotive problems using electronic scanning equipment. Mechanical diagnostic tools identify automotive problems using analog devices. Leak detectors test the fluid levels in vehicles and find leaks. Circuit testers identify electrical problems to ensure systems are receiving power. Trailer testers identify problems in the wiring between the truck and trailer to ensure circuits are connected and powered. Fuel injector diagnostic tools test and locate issues with fuel delivery systems. Vehicle heating and cooling diagnostic tools identify issues in automotive air conditioning and heating systems. Hydraulic flow meters, kits, and components measure, test, and maintain vehicle hydraulic systems. Mechanic stethoscopes isolate engine sounds to identify issues. Tire pressure monitoring system (TPMS) tools and components report air pressure to drivers to ensure safe operating levels.