Automatic Transmissions: Diagnosis Dodge Neon II

DIAGNOSIS AND TESTING - 41TE TRANSAXLE GENERAL DIAGNOSIS

Note. Before attempting any repair on a 41TE four-speed automatic transaxle, check for diagnostic trouble codes (DTC's) using the DRB scan tool. Refer to DIAGNOSIS - 41TE article.

Transaxle malfunctions may be caused by these general conditions

1. Poor engine performance
2. Improper adjustments
3. Hydraulic malfunctions
4. Mechanical malfunctions
5. Electronic malfunctions

Diagnosis of these problems should always begin by checking the easily accessible variables: fluid level and condition, gearshift cable adjustment. Then perform a road test to determine if the problem has been corrected or that more diagnosis is necessary. If the problem persists after the preliminary tests and corrections are completed, hydraulic pressure checks should be performed.

DIAGNOSIS AND TESTING - ROAD TEST

Prior to performing a road test, verify that the fluid level, fluid condition, and linkage adjustment have been approved.

During the road test, the transaxle should be operated in each position to check for slipping and any variation in shifting.

If the vehicle operates properly at highway speeds, but has poor acceleration, the converter stator overrunning clutch may be slipping. If acceleration is normal, but high throttle opening is needed to maintain highway speeds, the converter stator clutch may have seized. Both of these stator defects require replacement of the torque converter and thorough transaxle cleaning.

Slipping clutches can be isolated by comparing the "Elements in Use" chart (Scheme 153) with clutch operation encountered on a road test. This chart identifies which clutches are applied at each position of the selector lever.

A slipping clutch may also set a DTC and can be determined by operating the transaxle in all selector positions.

Scheme 153

The process of elimination can be used to detect any unit which slips and to confirm proper operation of good units. Road test analysis can diagnose slipping units, but the cause of the malfunction cannot be determined. Practically any condition can be caused by leaking hydraulic circuits or sticking valves.

DIAGNOSIS AND TESTING - HYDRAULIC PRESSURE TESTS

Pressure testing is a very important step in the diagnostic procedure. These tests usually reveal the cause of most hydraulic transaxle problems.

Before performing pressure tests, be certain that fluid level and condition, and shift cable adjustments have been checked and approved. Fluid must be at operating temperature (150 to 200°F.).

Install an engine tachometer, raise vehicle on hoist which allows front wheels to turn, and position tachometer so it can be read.

Attach 300 psi gauge (C-3293SP) to port(s) required for test(s) being conducted. Use adapter set L-4559 to adapt gauge(s) to transaxle.

Test port locations are shown in (Scheme 154)

Scheme 154

TEST ONE: SELECTOR IN LOW (1ST GEAR)

1. Attach pressure gauge to the low/reverse clutch tap.
2. Move selector lever to the (L) position.
3. Allow vehicle wheels to turn and increase throttle opening to achieve an indicated vehicle speed to 20 mph.
4. Low/reverse clutch pressure should read 115 to 145 psi.
5. This test checks pump output, pressure regulation and condition of the low/reverse clutch hydraulic circuit and shift schedule.

TEST TWO: SELECTOR IN DRIVE (2ND GEAR)

Note. This test checks the underdrive clutch hydraulic circuit as well as the shift schedule.

1. Attach gauge to the underdrive clutch tap.
2. Move selector lever to the 3 position.
3. Allow vehicle wheels to turn and increase throttle opening to achieve an indicated vehicle speed of 30 mph.
4. In second gear the underdrive clutch pressure should read 110 to 145 psi.

TEST TWO A: SELECTOR IN OD (4TH Gear)

Note. This test checks the underdrive clutch hydraulic circuit as well as the shift schedule.

1. Attach gauge to the underdrive clutch tap.
2. Move selector lever to the (OD) position.
3. Allow wheels to rotate freely and increase throttle opening to achieve an indicated speed of 40 mph.
4. Underdrive clutch pressure should read below 5 psi. If not, then either the solenoid assembly or TCM is at fault.

TEST THREE: OVERDRIVE CLUTCH CHECK (3RD & 2ND GEAR)

1. Attach gauge to the overdrive clutch tap.
2. Move selector lever to the (OD) position.
3. Allow vehicle wheels to turn and increase throttle opening to achieve an indicated vehicle speed of 20 mph. Vehicle should be in 3rd gear.
4. Overdrive clutch pressure should read 74 to 95 psi.
5. Move selector lever to the (3) position and increase indicated vehicle speed to 30 mph.
6. The vehicle should be in second gear and overdrive clutch pressure should be less than 5 psi.
7. This test checks the overdrive clutch hydraulic circuit as well as the shift schedule.

TEST FOUR: SELECTOR IN OVERDRIVE (4TH GEAR)

1. Attach gauge to the 2/4 clutch tap.
2. Move selector lever to the (OD) position.
3. Allow vehicle front wheels to turn and increase throttle opening to achieve an indicated vehicle speed of 30 mph. Vehicle should be in 4th gear.
4. The 2/4 clutch pressure should read 75 to 95 psi.
5. This test checks the 2/4 clutch hydraulic circuit.

TEST FIVE: SELECTOR IN OVERDRIVE (4TH GEAR-CC ON)

1. Attach gauge to the torque converter clutch off pressure tap.
2. Move selector lever to the (OD) position.
3. Allow vehicle wheels to turn and increase throttle opening to achieve an indicated vehicle speed of 50 mph. Vehicle should be in 4th gear, CC on. CAUTION: Both wheels must turn at the same speed.
4. Torque converter clutch off pressure should be less than 5 psi.
5. This test checks the torque converter clutch hydraulic circuit.

TEST SIX: SELECTOR IN REVERSE

1. Attach gauges to the reverse and LR clutch tap.
2. Move selector lever to the (R) position.
3. Read reverse clutch pressure with output stationary (foot on brake) and throttle opened to achieve 1500 RPM.
4. Reverse and LR clutch pressure should read 165 to 235 psi.
5. This test checks the reverse clutch hydraulic circuit.

TEST RESULT INDICATIONS

1. If proper line pressure is found in any one test, the pump and pressure regulator are working properly.
2. Low pressure in all positions indicates a defective pump, a clogged filter, or a stuck pressure regulator valve.
3. Clutch circuit leaks are indicated if pressures do not fall within the specified pressure range.
4. If the overdrive clutch pressure is greater than 5 psi in Step 4 of Test Three, a worn reaction shaft seal ring or a defective solenoid assembly is indicated.
5. If the underdrive clutch pressure is greater than 5 psi in Step 4 of Test Two A, a defective solenoid assembly or TCM is the cause.

Scheme 155

DIAGNOSIS AND TESTING - CLUTCH AIR PRESSURE TESTS

Inoperative clutches can be located using a series of tests by substituting air pressure for fluid pressure. ( see scheme 7 and see scheme 8 ). The clutches may be tested by applying air pressure to their respective passages. The valve body must be removed and Tool 6056 installed. To make air pressure tests, proceed as follows

Note. The compressed air supply must be free of all dirt and moisture. Use a pressure of 30 psi.

Remove oil pan and valve body. See Valve body removal.

DIAGNOSIS AND TESTING - BRAKE TRANSMISSION SHIFT INTERLOCK

The following chart describes the normal operation of the Brake Transmission Shift Interlock (BTSI) system. If the "expected response" differs from the vehicle's response, then system repair and/or adjustment is necessary. Refer to Brake Transmission Interlock Removal and Installation or Adjustment. (Scheme 156)

Scheme 156