When building Automatic Transmissions installing the original or new solenoids is a common thing, so you need to know the solenoids you are installing has the correct ohms and you need to know if the solenoid has a voltage spike suppressor diode in the solenoid. Because it's a long way back into the Transmission or Transaxle to get to a defective solenoid. With the solenoids on the bench is the time to figure these 2 things out. You can use your digital OHM meter to figure out the correct OHMS but the digital OHM meter will not tell you if the solenoid has a suppressor voltage spike type devise or if its even working. I still have and use the old school analog OHM meter to check the voltage spike devise in the solenoids. When you check the OHMS with the analog OHM meter you get some type of reading 10 or 20 OHMS is common. By reversing the polarity with your leads you will get a small OHM reading up or down from your first reading and that's good. If your analog meter shows the same OHM reading in both directions of polarity your solenoid either doesn't have a voltage spike devise or the devise is blown. The digital OHM meter does not send enough current through the solenoid to allow you to test the suppressor diode.
Voltage spike has to be controlled when a solenoid turns off. This info is not just for Transmission bench work. Paul Townsend Paul's Transmission & Repair.
