Issue Summary:
- 4R44E/4R55E or 5R55E units in 4WD Ford Explorers fall out of gear while either on throttle or coasting, and at times there is a ratcheting noise.
- Chrysler LH vehicles with 3.5-liter engines may experience a code 1391 after transmission replacement.
- Line rise in Chrysler 904, 727, 500/618 and pre-1996 RE units is sluggish and, in many instances, insufficient.
- 1996 and newer full-size V-6 Ram Cargo Vans with three-speed 999T transmissions produce a code P0740 after overhaul.
- Some 2000-01 Ram Vans, Dakotas, Ram trucks and Durangos may exhibit a flashing Check Engine Light, caused by code P1740.
- Before or after overhaul, Chrysler or Jeep vehicles with 42RE-46RE transmissions may exhibit stalling in Reverse or repeated planetary failure.
4R44E/4R55E or 5R55E transmissions in four-wheel-drive Ford Explorers fall out of gear while either on throttle or coasting, and at times there is a ratcheting noise. The manual-lever-position sensor and its circuits have been inspected and determined to be functioning correctly. Solenoid commands are checked, and no abnormality is observed.
The problem is in the transfer case. After it is disassembled, you find that either the fork tips have burned away because of low oil levels, causing excessive play, or the fork’s shift rail has caused the holding boss in the rear-case cover to become egg shaped, causing excessive shift-fork play (see Figure 1).
The geometry of the fork and cam results in excessive side-load force on the fork rail, causing the wear in the rear cover. Additionally, the electronic shift-control system, known as Control-Trac, in the Explorer’s BorgWarner 44-05 transfer case may contribute to acceleration of this problem.
When the transfer case is in auto 4WD, if the tires are low on air pressure, unevenly worn or an incorrect size, the generic electronic module (GEM) may observe a slip ratio because of different speed signals from the front and rear speed sensors and activate the electromagnetic clutch in the transfer case in an attempt to equalize driveshaft speed. This clutch engagement adds additional force through the output shaft to the fork. With the side-load problem, the fork’s shaft will wear the rear case much more quickly.
Repair damage to fork tips and/or the fork-rail bore in the rear case.
Chrysler LH vehicles such as LHS, Concorde, Intrepid, New Yorker and Vision with 3.5-liter engines may experience a code 1391 “Intermittent Loss of Crank or Cam Signal” after transmission replacement. This will be accompanied by a rough-running engine that cannot remain at idle for more than four to six seconds. The vehicle ran smoothly before the needed transmission work was performed. The crankshaft and camshaft speed sensors were replaced without any success. The crankshaft speed sensor, in the converter housing (see Figure 2), is not adjustable in vehicles with 3.5-liter engines, so the sensor exciter ring on the fly-wheel (see Figure 3) may be suspect. But after an inspection it proves to be good.
One known cause has been that during the removal or installation of the transmission, while the technician was turning the torque converter, the crankshaft kicked back because of engine compression, causing the timing belt to skip one cog, or the crankshaft was turned in the opposite direction of normal engine rotation, causing the skip (see Figure 4). This incident had occurred with a vehicle that had 80,000-plus miles, so the timing belt was worn.
Reposition or replace the timing belt.
Special Note:
Jeeps with 42REs also may experience a rough-idling, poorly performing engine after transmission overhaul. This may be caused by a rebuilt converter with its balance weights mounted too close to the outside diameter of the converter, causing them to interfere with the crankshaft-sensor reading.
It is commonly known that line rise in rear-wheel-drive Chrysler transmissions (904, 727, 500/618 and all pre-1996 RE units) is sluggish and, in many instances, insufficient. As a result, technicians often find themselves having to adjust the throttle rod/cable in an attempt to locate a happy medium for shift feel and shift timing. Many times the vehicle is delivered without really achieving the desired shift characteristics.
The cause is decrease pressure supplied to the pressure-regulator-valve throttle plug, which is used to prevent line pressure from exceeding about 100-120 psi at wide-open throttle (see Figure 5).
Drilling a 0.040-inch exhaust hole through the exterior casting into the decrease-pressure circuit, as described in the following example and illustrated in Figure 6, will provide a controlled venting of this oil, which will allow a more-rapid line-rise response to throttle opening, improving the shift characteristics of the transmission. It also will allow a more-desirable top-end line-pressure reading and a slight increase in the converter-clutch apply pressure.
Step 1. Measure the overall length of the plug (0.480 inch in the example in Figure 6).
Step 2. Measure the length of the plug minus one shoulder (0.430 inch in the example in Figure 6).
Step 3. The difference between the two readings is 0.050 inch. By dividing that number in half (0.025 inch) and adding it to the figure acquired in step 2 (0.430 inch), you can mark the depth from the edge of the bore to the decrease circuit for drilling at about 0.455 inch as shown in Figure 6.
Note:
In 1996 and later vehicles, drilling this hole may cause an erroneous code P1763 “Transmission Governor Pressure Sensor Volts Too High.” You can overcome this by reflashing the PCM according to Chrysler bulletin 21-04-00 to recalibrate the JTEC Powertrain Control Module with new software (calibration change 96Cal18, 97Cal18, 98Cal12 and 99Cal14).
1996 and newer full-size V-6 Ram Cargo Vans with three-speed 999T (904 Torqflite with TCC solenoid) usually found in fleet services produce a code P0740, “No Or Insufficient RPM Drop During TCC,” after overhaul. The converter was replaced at the time of rebuild and replaced several more times in an attempt to solve the problem. The solenoids, valve body and even the computer have been replaced without resolving the problem.
These particular vehicles use converters with very high stall speeds (about 3,000 rpm in some instances). When a lower-stall converter is installed, the computer does not see the required speed drop when the torque-converter clutch applies, producing the code.
If the converter does not need to be replaced, don’t replace it. If it does need to be replaced, insist on having the original converter rebuilt. Going to the dealer to buy a new converter also has been known to be unproductive.
Note:
Usually these vans are equipped with the four-speed RE unit, which is why all reference materials provide only four-speed information. This is your tip that you are working on a special fleet-service vehicle with no frills, bells or whistles. Keep that converter!
Tip:
Gary Carne from Freeway Transmissions had several vehicles at one time with this problem, as the shop had an account using these commercial vans that Chrysler does not recognize as a factory option. He had to make converters to solve the problem. He converted a 2.5-liter 604 10-inch converter to fit this application.
Some 2000-01 Ram Vans, Dakotas, Ram trucks and Durangos may exhibit a flashing Check Engine Light, caused by code P1740 (a torque-converter-clutch or overdrive-solenoid performance fault).
The cause may be a reducing-pressure exhaust orifice that is too small, which delays the pressure increase needed when the torque-converter clutch is applied. Refer to figures 7 and 8 for partial hydraulic schematics explaining the boost valve’s function.
Refer to Figure 9 to locate the reducing-pressure exhaust orifice, which is in the boost-valve cover plate. Remove the plate and enlarge the orifice shown to 0.069 inch. Chrysler also provides a new boost-valve cover plate that has the enlarged orifice.
Boost-valve cover plate (Chrysler part number) . . . . . . . . . . . .04617012
Before or after overhaul, Chrysler or Jeep vehicles equipped with 42RE-46RE transmissions may exhibit a stalling condition in Reverse or repeated planetary failure.
The cause may be a restricted auxiliary transmission cooler.
NOTE: During the flushing process, this may be overlooked because of a bypass tube (see Figure 10) that connects the two cooler lines, misleading the technician into thinking that the auxiliary transmission cooler is clear.
The auxiliary transmission cooler cannot be flushed very easily because of its fin-type construction (see Figure 11). This also can cause hanging valves and continual clogging of the governor-solenoid screen.
Replace the auxiliary transmission cooler as needed.
April 2003 Issue
Volume 20, No. 4
- Ford Explorer 4×4: Neutralizing While on Throttle or Coasting
- Chrysler LH vehicles: Code 1391: Intermittent Loss of Crank or Cam Signal
- Chrysler RWD Transmissions: Improved Line-Rise Throttle Response
- Dodge Ram Cargo Vans: Code P0740: No or Insufficient Speed Drop During TCC Application
- Chrysler 46RE: Diagnostic Trouble Code P1740
- Chrysler or Jeep 42RE-46RE: Stalling in Reverse or Planetary Failure