Road Testing Vehicle

ROAD TESTING VEHICLE
The Shift Point Road Test and Torque Converter Clutch Operation Test provide diagnostic information on transmission shift controls and torque converter operation.

Shift Point Road Test
This test verifies that the shift control system is operating properly.
1. Bring engine and transmission up to normal operating temperature.
2. Operate vehicle with transmission selector in D range.
3. Apply minimum throttle and observe speeds at which upshift occurs and torque converter engages. Refer to the Shift Speeds chart.
4. Stop the vehicle. Depress transmission control switch and overdrive "off" switch (O/D OFF) to activate D range. Repeat Step 3. Transmission will make all upshifts except 3-4 (4R44E) or 4-5 (5R55E) and torque converter clutch apply should occur above 46 km/h (27 mph).
5. Press accelerator pedal to floor, Wide Open Throttle (WOT). Transmission should shift from third to second, or third to first, depending on vehicle speed, and torque converter clutch should release.
6. With vehicle speed above 48 km/h (30 mph), move the selector lever from D range to 1 range (LOW) and release accelerator pedal. Transmission should immediately downshift to second (4R44E) or third (5R55E) gear. When vehicle speed drops below 32 km/h (20 mph), transmission should downshift into first gear.
7. If transmission fails to upshift/downshift or torque converter clutch does not apply/release, refer to Diagnosis By Symptom.





4R44E Shift Speeds








5R55E Shift Speeds

Note Shift Speed Ranges are approximate for all applications.

Torque Converter Diagnosis
Prior to torque converter replacement, all diagnostic procedures must be followed. This is to prevent the unnecessary replacement of good torque converters. Only after a complete diagnostic evaluation can the decision be made to replace the torque converter.
Begin with the normal diagnostic procedures as follows:
1. Preliminary Inspection.
2. Know and Understand the Customer's Concern.
3. Perform the Torque Converter Operation Test.
4. Perform Diagnostic Procedures.
- Refer to run on-board diagnostics.
- Repair all non-transmission related DTCs first.
- Repair all transmission DTCs.
- Rerun on-board diagnostic to verify repair.
- Perform Line Pressure Test.
- Perform Stall Speed Test.
- Perform Diagnosis by Symptom Procedure.

Torque Converter Operation Test
This test verifies that the torque converter clutch control system and the torque converter are operating properly.
1. Perform Quick Test.
2. Connect a tachometer to the engine.
3. Bring the engine to normal operating temperature by driving the vehicle at highway speeds for approximately 15 minutes in D (Overdrive) position.
4. After normal operating temperature is reached, maintain a constant vehicle speed of about 80 km/h (50 mph) and tap brake pedal with the left foot.
- Engine rpm should increase when brake pedal is tapped, and decrease about five seconds after pedal is released.
- If this does not occur, refer to Diagnosis By Symptom; Torque Converter Operation Concerns. Repair as required.
5. If the vehicle stalls in D (Overdrive) or manual 2 at idle with vehicle at a stop, move the transmission range selector lever to manual 1 position.
- If the vehicle stalls, refer to Diagnosis By Symptom; Torque Converter Operation Concerns. Repair as required.
- If the vehicle does not stall in D (Overdrive), refer to Diagnosis By Symptom.