Issue Summary:
- Before or after overhaul, 1989-95 vehicles equipped with E4OD transmissions may exhibit a delayed bang shift into reverse.
- Beginning at the start of production for the 1999 model year, some models of the THM 4T65-E were produced with an internal mode switch, attached to the selector detent inside the transmission side cover.
Before or after overhaul, 1989-95 vehicles equipped with E4OD transmissions may exhibit a delayed bang shift into reverse.
The cause may be a weak low/reverse modulating-valve spring causing a timing problem with application of the direct and low/reverse clutches.
Replace the original low/reverse modulating-valve spring with a spring that has double the tension (see Figure 1), offered by Superior Transmission Parts.
This will sequence application of the low/reverse clutch with application of the direct clutch as shown in the partial schematic in Figure 2.
NOTE: This modification should be performed only on 1989-95 models.
Figure 3 identifies the three different low/reverse modulating-valve line-ups.
See Figure 4 for the hydraulic changes that were produced for 1996 E4OD units and for 4R100 models.
- Superior Transmission Parts “no bang” engagement springs, 3 per box . . . . . . . . . . . . . . . . . . . . . . . . . .K043
Beginning at the start of production for the 1999 model year, some models of the THM 4T65-E were produced with an internal mode switch (IMS). The IMS is a sliding contact switch attached to the selector detent inside the transmission side cover (see Figure 5).
The four inputs to the PCM from the IMS indicate the position selected by the transmission selector lever. This information is used for ignition timing, EVAP canister purge, EGR and IAC-valve operation, as well as for starting functions when the selector lever is in P or N and proper ground is made. The state of each input is available for display on the scan tool. The four input parameters represented are modes P, A, B and C (refer to Figure 6).
Mounted internally for increased protection from the elements and from engine-compartment heat for increased durability and reliability. This also eliminates the need for adjustments at the vehicle assembly plants.
Mode switch – Now mounted internally instead of externally on the transaxle case on some models (see Figure 5).
Internal wire harness – Five wires added to the internal harness to accommodate the new mode switch. The wires run through the transaxle-case connector (see Figure 6).
1. Faults in the IMS can generate the following DTCs:
- P1819 – Internal mode switch, no start/wrong range
- P1820 – Internal mode switch, circuit “A” low
- P1822 – Internal mode switch, circuit “B” high
- P1825 – Internal mode switch, invalid range
- P1826 – Internal mode switch, circuit “C” high
Note: None of these DTCs will illuminate the malfunction indicator lamp (MIL).
2. Refer to Figure 6 for IMS connector-terminal identification, wire colors and circuit functions.
3. Refer to Figure 7 for a complete wiring schematic from the transaxle through the transaxle-case connector and on to the powertrain control module (PCM). This includes wire colors both inside and outside and terminal identification of transaxle components.
4. Refer to Figure 8 for identification of the transaxle-case connector terminals that were added to accommodate the IMS, and the wire colors and functions. We also have included a resistance chart for the internal transaxle components.
5. Refer to Figure 9 for identification of the PCM connector terminals, both blue and the clear connectors for the transaxle-related components.
6. Refer to Figure 10 for an IMS logic chart that will provide you with the proper readings for all four input parameters for the IMS. These can be viewed from the appropriate scan tool.
7. Figure 11 provides you with the information to bench check the IMS for the proper continuity at the IMS connector, and Figure 12 provides you the same information to check the switch at the transaxle-case connector terminals.
June 2003 Issue
Volume 20, No. 6
- Ford E4OD: Delayed Reverse
- THM 4T65-E: Internal Mode Switch Added in Some Models