Issue Summary:
- A 1999 Mercury Sable with a 3.0-liter engine and AX4N transmission has codes P0708 and P1702 stored and has shift-scheduling problems.
- VW and Audi vehicles equipped with the 01M, 01N or 01P transaxles may exhibit a flare on the 3-4 upshift or a quick spin-up during the shift.
A 1999 Mercury Sable with a 3.0-liter engine and AX4N transmission came into the shop with codes P0708 and P1702 set along with shift-scheduling problems. This would indicate a problem with the digital transmission-range sensor (DTRS) or its circuits. After installation of a new range sensor, the same codes returned along with the shift complaints.
At this time the technician acquired a wiring diagram and discovered that this vehicle could be equipped with either a manual-lever-position sensor (MLPS) or a DTRS.
Because the original sensor on this vehicle was a 12-pin configuration, it was replaced with a 12-pin DTRS. This immediately resulted in the codes mentioned previously, because this vehicle requires an MLPS, not a DTRS. The newer (second-design) MLPS has a 12-pin connector configuration exactly like the DTRS connector, so they appear to be the same component.
When the 12-pin DTRS was installed in this vehicle the PCM set the codes, because a DTRS in this vehicle could never range correctly. The MLPS is a step-down resistor style that indicates about 4.5 volts in park and drops as you move the selector lever toward low, in which it indicates about 0.75 volt. The DTRS produces a combination of circuits to the PCM that can be 5 or 1-12 volts while others are grounded. This combination of voltage and grounded circuits tells the PCM where the gear-selector lever has been positioned. Figure 1 illustrates the MLPS internal electrical structure, and Figure 2 shows the eight- and 12-pin connectors and the MLPS ranging logic.
Figure 3 illustrates the DTRS internal electrical structure, and in Figure 4 you can see the 12-pin connector and the DTRS ranging logic.
Once the MLPS was installed, the codes were gone along with the shift complaints.
The way to determine which sensor is required, other than checking the circuits for voltage, is the vehicle identification number. The break points using the eighth VIN digit for engine type follow:
- 1998/1999 Taurus VIN N for SHO models and VIN S for all other models – 12-pin MLPS.
- 1998/1999 Taurus VIN 1 or 2 for flex-fuel-equipped vehicles and VIN U – 12-pin DTRS.
- 1998/1999 Sable VIN S – 12-pin MLPS.
- 1998/1999 Sable VIN U – 12-pin DTRS.
- 12-pin manual-lever-position sensor . . . . . . . . . . . . . . . . .F6DZ-7F293-A
- 12-pin digital transmission-range sensor . . . . . . . . . . . . .F8DZ-7F293-AD
VW and Audi vehicles equipped with the 01M, 01N or 01P transaxles may exhibit a flare on the 3-4 upshift or a quick spin-up during the shift.
The cause may be low solenoid-feed pressure, a worn solenoid-regulator-valve bore or a missing spring for checkball No. 4. This can cause a flare on the 3-4 upshift because of the lack of pre-fill on the K1 clutch. This pre-fill pressure ranges from 3 to 10 psi and begins at the solenoid regulator valve, is fed through two 0.040-inch orifices and is finally regulated by the No. 4 checkball and spring. The lack of pre-fill can cause the K1 clutch to release too quickly during the 3-4 upshift transition. Figure 5 provides a partial circuit diagram.
To correct this condition, ensure that the solenoid casings are sealed against the valve-body casting by using gaskets (figures 6 and 7).
Check the bore of the solenoid regulator valve and repair the bore if necessary. See Figure 8 for a cross-sectional view and Figure 7 for the valve location.
Verify that the spring under checkball number 4, as shown in Figure 9, is in the correct location.
Solenoid gaskets are available in some aftermarket overhaul kits. Valve repair and a replacement spring for the No. 4 checkball are available from Sonnax.
January 2010 Issue
Volume 27, No. 1
- Ford Taurus/Mercury Sable AX4N: Manual-lever-position sensors/digital range sensors
- VW/Audi 01M/01N/01P: Flare on 3-4 upshift