COMPLAINT: When the manual selector lever is placed into either Drive and/or Reverse from the Park and/or Neutral position, a “Buzzing” noise is heard coming from the transaxle area for approximately one to two seconds and then stops. Find obd2 scanner?
CAUSE: This noise is created by the solenoid assembly which includes four different solenoids.
CORRECTION: The “Buzzing” noise described above is NORMAL. The ONLY thing that can be done to help alleviate the “Buzzing” noise, is to ensure that the Solenoid Assembly Sound Cover is present, and installed properly as shown in Figure 1.
DELAYED FORWARD ENGAGEMENT OR PREMATURE FAILURE OF THE FORWARD CLUTCH
COMPLAINT: ZF-4HP-18 transmissions may exhibit a no move condition in any forward range and works fine in reverse.
CAUSE: One cause may be that either the 3-4 or 4-3 traction valve in the valve body has stuck in a stroked position preventing forward clutch apply (See Figure 18).
CORRECTION: Remove the valve body from the transaxle. Inspect and free the valve that is stuck.