Diagnosing the 2011 Chevrolet Volt 4ET50 Transmission
drive the vehicle. During the test drive, try to dupli-
cate the customer’s complaint. After the test drive, check whether any codes have reset. Repair all non-transmis- sion related codes stored in the system before starting any diagnostic routines on the transmission control system. Refer to figure one for a list of codes and definitions that you may find while scanning the TCM. Note: Figures 3 and 4 are mentioned in this chart. After performing any repairs on
the 4ET50 transmission, reset the trans- mission adapts to ensure proper trans- mission operation (figure 2). Failure to perform the reset trans-
mission adapts procedure after any of these repairs may result in poor trans- mission performance, DTCs, or a com- plete transmission failure.
Resetting Transmission Adapts Use your scan tool to reset the
transmission adapts. The scan tool will prompt you through the reset proce- dure. 1. Follow the reset procedure steps on your scan tool. [CAUTION] If you fail to main- tain the required conditions anytime during the adapt reset procedure, your scan tool will abort the procedure. If this happens, the transmission will be left in a neutral state until the TCM shuts down. If that happens:
• Turn the key off. • Disconnect the scan tool. • Wait more than 30 seconds before retrying the reset pro- cedure again.
2. Once you’ve completed the reset procedure, exit back to the main screen in the scan tool, shut the scan tool off, and unplug it from the DLC connector.
3. Turn the vehicle off and allow the TCM to power down.
4. Turn ignition key on. This will complete the Reset Transmission Adapts procedure.
5. Road test vehicle to verify proper transmission operation.
Figure 3 12 GEARS March 2012
High Voltage System Service If you’re working around the vehi-
cle’s high voltage system or performing a major repair to the transmission, such as an R&R or a rebuild, you’ll have to disable the high voltage system. Use the following procedure to safely disable the high voltage system.
Dangers and Warnings Related to the High Voltage System Follow all high
voltage safety pro- cedures. Failure to follow the proce- dure exactly may result in serious injuries or death due to electrocu- tion.
Before attempting to work on any
high voltage system, be sure to wear the proper Personal Protection Equipment: • Wear safety glasses with side shields whenever you’re within 50 feet of the vehicle, whether you’re indoors
Reset Transmission Adapts after the following Repairs
1. Internal transmission service or overhaul 2. Valve body Repair 3. TCM/valve body replacement 4. TCM software or calibration update 5. Any service performed in response to a shift quality concern
Following Conditions Must be Met before Resetting Transmission Adapts
1. Drive wheels Blocked 2. Parking brake applied 3. Service brake applied 4. Zero percent throttle angle and no external RPM control
5. Transmission fluid at normal operating temperature (158°-239° F)
6. Transmission selector lever cycled between Park & Reverse 3 times
Figure 2Figure 2
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