Transmission Test Box Tool
Transmission Test Box.:
Figure 1 - Transmission Test Box.
Solenoid Operation.:
Figure 2 - LED indicators of test box.
DESCRIPTION
A transmission test box, J 38791, and transaxle harness J-38791-10, is recommended to diagnose whether the cause of a problem is in the vehicle PCM wiring harness or in the transaxle.
The test box allows the technician to monitor vehicle electrical outputs through illumination of LED's, measure component resistance or perform other electrical checks through pin-out jacks, and control transaxle shifts or TCC/VCC operation while road testing the vehicle to conduct functional tests.
LED indicators on the test box monitor the presence of voltage at the PCM ignition input, brake switch, TCC/VCC apply solenoid, TCC/VCC modulate solenoid, and Shift A and Shift B solenoids. Pin-out jacks for these circuits are also provided just below each respective LED to facilitate probing with a digital volt ohmmeter when required. A gear selector switch and a converter clutch operation switch are located near the bottom of the face panel. A vehicle system ground pin-out jack is located at the bottom.
The test box is installed by connecting its harness connectors between the vehicle harness connector and transaxle connector, routing the harness under the hood through the driver's door window into the passenger compartment, and inserting the ground connector into the cigarette lighter receptacle, (Figure 1).
USING THE TRANSMISSION TEST BOX
IMPORTANT: Before installing the Test Box, check the vehicle diagnostic system for PCM related codes.
NOTICE: To avoid damage to the transmission due to overstress, observe the following when using this tool:
^ Do not start vehicle from a stop in 3rd or 4th gear setting.
^ Do not shift to 1st gear setting above 40 km/h (25 mph).
^ Do not brake torque vehicle with tool attached.
^ Do not move converter clutch switch to the ON position when vehicle speed is less than 40 km/h (25 mph).
^ Do not place vehicle shift selector lever in manual first or manual second.
1. Connect the test box.
a. Disconnect the vehicle transaxle wiring harness from the transaxle.
b. Connect the test box connectors into the vehicle harness and transaxle.
c. Route test box harness under the hood, through the driver's window. Use a tie strap if necessary to keep the test box harness away from the exhaust manifold or cooling fan (refer to Figure 5).
d. Insert the Power/ground connector into the cigarette lighter receptacle in the passenger compartment. Observe that the battery LED comes ON
e. Turn the ignition ON.
f. Set up the on-board diagnostics
2. Place the gear selector and converter clutch switches on the test box to the NORMAL positions.
3. Perform functional tests for brake switch and all gears including TCC/VCC. Remember the engine must be up to minimum operating temperature of approximately 75°C (167°F) for TCC/VCC operation. Tests can be done in bay and/or road test. Observe the LED indicators of test box as shown in figure 2.
TRANSAXLE TEST BOX (J-38791) LED's will illuminate as follows:
BATTERY: LED "ON" indicates power cord is plugged into the lighter receptacle (test box will not operate properly without a proper ground through the lighter receptacle).
IGN: LED "ON" indicates voltage is present at Pin E of the transmission connector. This voltage should be battery voltage when the ignition is ON and if the circuit, including the fuse, is OK. IGN provides power to one side of Shift A, Shift B, and TCC MOD solenoids.
BRAKE: LED "ON" indicates a battery voltage is present at Pin A of the transmission connector. The LED should be ON with ignition ON and brake not applied. This circuit provides power to one side of the TCC/VCC apply solenoid.
CONVERTER CLUTCH APPLY: LED "ON" indicates a ground is present at terminal D of the transmission connector.
CONVERTER CLUTCH MOD: LED "ON" indicates a ground is present at terminal B of the transmission connector. This LED will illuminate only during converter clutch apply or during PCM output cycling. It will not illuminate when the test box converter clutch switch is in the "ON" position.
SHIFT A: LED "ON" indicates a ground is present at Pin F of the transmission connector to energize solenoid A. Ground is provided by the PCM when the test box rotary switch is in the NORMAL position, or by the test box when the switch is in first or fourth gear position.
SHIFT B: LED "ON" indicates a ground is present at Pin G of the transmission connector to energize Shift B solenoid. Ground is provided by the PCM when the test box rotary switch is in the NORMAL position or by the test box when the switch is in first or second gear position.
LO DISCRETE 2-3, 3-4: Do not apply diagnosing the 4.9 PFI (L26) version of the 4T60-E transaxle.
IMPORTANT: The LED indicators show the electrical states at the transmission connector, but do not check the wiring, solenoids, or hydraulics inside the transmission. The LEDs indicate whether the PCM control system and wiring is OK. The override switches must be used in conjunction with a road test to verify transmission operation.