Shift Pointers
- Subject: Hard 1-2 upshift
- Unit: RE4F03/4B
- Vehicle Application: Nisssan
- Essential Reading: Rebuilder, Diagnostician
- Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor
The RE4F03/4B transmission in several Nissan vehicles develops a hard 1-2 upshift as a result of uncontrolled line pressure. Sometimes code P0745 is stored for a problem in the line-pressure-control solenoid circuit. Replacing the solenoid assembly usually fixes the problem. But, the next time this happens to you, or you get to experience this for the first time, the fix may be as simple as gently squeezing a crimp.
The pressure-control solenoid is grounded internally through an eyelet bolted to the valve body (Figure 1).
Remove the bolt and tug on the wire to see whether the crimp is clamped down into the wire properly (figures 2 and 3). There are instances in which the crimping process did not clamp it down sufficiently and the wire becomes loose. If you discover a loose-fitting wire, give the crimping a gentle squeeze to restore tight contact. There may be instances in which a little solder would be in order.
Also take a look at the crimp where the wires come out of the solenoid (Figure 4).
If this has been lifted up, give it a gentle push down (figures 5 and 6). This will take tension off the wire, giving it the slack it needs to prevent vibration from pulling it loose again.
