Service and Repair Manual April 2018Manifolds120 ZX®-135/70 Part No. 1279835GT8-13Valve CoilsHow to Test a CoilA properly functioning coil provides anelectromotive force which operates the solenoidvalve. Critical to normal operation is continuitywithin the coil that provides this force field.Since coil resistance is sensitive to temperature,resistance values outside specification canproduce erratic operation. When coil resistancedecreases below specification, amperageincreases. As resistance rises above specification,voltage increases.While valves may operate when coil resistance isoutside specification, maintaining coils withinspecification will help ensure proper valve functionover a wide range of operating temperatures.Electrocution/burn hazard.Contact with electrically chargedcircuits could result in death orserious injury. Remove all rings,watches and other jewelry.1 Tag and disconnect the wiring from the coil tobe tested.2 Test the coil resistance.Result: The resistance should be withinspecification, plus or minus 30%.Result: If the resistance is not withinspecification, plus or minus 30%, replace thecoil.Valve Coil ResistanceSpecificationNote: The following coil resistance specificationsare at an ambient temperature of 68°F / 20°C. Asvalve coil resistance is sensitive to changes in airtemperature, the coil resistance will typicallyincrease or decrease by 4% for each 18°F / 10°Cthat your air temperature increases or decreasesfrom 68°F / 20°C.Valve Coil Resistance Specification3 position 4 way solenoid valve(schematic item A, B, C, D, W)7.2Ω2 position 3 way solenoid valve(schematic items D, E, F, G, I, Z )5.6Ω2 position 3 way solenoid valve(schematic items P,Q )7.2Ω2 position 3 way solenoid valve(schematic items AE )8.8Ω3 position 4 way proportional solenoid valve(schematic items Y and AF)8.8Ω2 position 2 way solenoid valve(schematic item A)3.5 to5.5Ω
