- When a vehicle equipped with the THM 4L60-E will not start in Neutral, the cause may be the Park/Neutral switch or the C1 or C2 repair harness.
- Trouble code P1870 in THM 4L60-E units usually results from slippage of the torque-converter clutch. Proper procedures for assembly of the front pump on the Ford 5R55N are important, because some misassemblies can occur if the technician does not refer to the manual.
- For example, the outer pump gear must be placed in the pump body with the ID marks facing down.
Vehicles equipped with 4L60-E transmissions may not start in Neutral, and the PRNDL indicator lights on the instrument panel and/or the back-up lights may not be functioning properly.
The cause may be an improperly adjusted or faulty park/neutral switch or an improperly wired C1 or C2 repair harness.
See Figure 1 to adjust the park/neutral switch correctly.
Referring to Figure 2, check the park/neutral switch in each range to ensure its integrity.
See Figure 3 for a wiring schematic illustrating the common wire colors and the placement of the wires in the C1 and C2 harness connectors.
- Park/Neutral Switch …………………………….12450016
- C1 Repair-Connector Assembly (with heat-shrink tube) …15305887
- C2 Repair-Connector Assembly (with heat-shrink tube) …15305925
Some vehicles may return consistently, before and/or after rebuild, with “Check Engine” lamp illuminated and trouble code P1870 (internal component slipping) stored in memory.
The cause usually is slippage of the torque-converter clutch, resulting from a badly worn valve-body casting in the converter-clutch-regulator valve bore.
Sonnax manufactures two different kits to repair the current valve-body castings, both of which require a reamer, also available from Sonnax. One of the kits, Sonnax part number 77754-03K, fits transmissions in the 1993-97 model years, but some of these units require different assembly processes. For the proper procedures, see Figure 4 for 1993-94 models and Figure 5 for 1995-97 models.
The other kit, Sonnax part number 77754-04K, fits only 1998 and later ECCC models, as that unit requires a different calibration. See Figure 6 for proper assembly for 1998 and later models. The reamer required is the same for either kit and is available as Sonnax part number 77754-R2.
Differences between the kits follow:
- 1993-97 models – The TCC regulator valve is 0.398 in. in diameter, which is 0.042 in. smaller than the isolator valve, for improved rate of apply.
- 1998-Up models – The TCC Regulator Valve is 0.440 in. in diameter, which is the same diameter as the isolator valve and is not recommended for the earlier models.
Figure 7 shows torque-converter identification for 298mm and 300mm converters only.
Some different procedures need to be addressed concerning the assembly of the front pump on the new 5R55N transmission (Figure 8) from Ford Motor Co.
Some of these procedures are different enough that some misassemblies can occur easily if the technician does not refer to the manual. ATSG will have an assembly/disassembly manual available soon.
- (1) The inner and outer pump gears must be placed into the pump body with the identification marks facing down, as shown in Figure 9. If they are placed in the opposite direction, the inner-gear O-ring will be in the wrong position, and installing the torque converter will be very difficult if not impossible.
- (2) This pump body has a line-pressure relief valve that most other transmissions do not have. Install the valve in the direction shown in Figures 10A and B and 11.
- (3) The pump-alignment tool is mandatory with this transmission and is the same one used on the A4LD, 4R44E/4R55E and 5R55E transmissions, as shown in Figure 12. Pump-alignment pins also are necessary for this transmission.
- (4) Figure 13 shows the inner-pump-gear O-ring sizer used to ensure that the O-ring is fully seated in the groove in the inner gear.
April 2001 Issue
Volume 18, No. 4
- THM 4L60-E: Park/Neutral-Switch Diagnosis
- THM 4L60-E: Trouble Code P1870
- Ford 5R55N: Front-Pump Assembly