Freightliner AMT 3 and Mercedes-Benz Automated-Manual Transmissions 26.03 Troubleshooting Without Fault Codes IMPORTANT: Always use ServiceLink when at- tempting to diagnose problems with the auto- mated gear shift (AGS) transmission. Use the electrical pre-test instructions given in Table 1 as a baseline for troubleshooting when there is no definite problem, the malfunction is erratic or intermittent, or as an informational step to determine the general health of the electrical system. To record your findings, a result sheet is provided at the end of this subject. For locations of serial numbers, see Fig. 1 and Fig. 2 .
In most cases, the J1587 fault code is the starting point for the troubleshooting procedures. See Sub- ject 300 for a list of fault codes and the location of troubleshooting procedures for each code. Electrical Pre-Test Instructions Before starting any procedures, use ServiceLink to depressurize the AGS hydraulic system. For detailed procedures, see Subject 160 . Procedure Result Action Electrical Pre-Test Make sure that the selector switch on the SmartShift lever is set to N. Turn on the ignition switch to power up the transmission. The current gear indicator does not power up normally. No fault codes display. Troubleshoot the current gear indicator. See Table 4 . NOTE:
If the hydraulic pump starts up with its characteristic humming noise, this means the main power cables are OK (see the steps below to check the X3 connector). The current gear indicator goes through its normal power-up sequence, ending by displaying "N." Turn off the ignition switch and go to the next row in the table. With the ignition switch off, check the voltage at the battery. Voltage is less than 11 or greater than 13 volts. Charge or replace the battery. For battery charging procedures, see Section 54.12 , Subject 150. Voltage is between 11 and 13 volts. Go to the next row in the table. Remove the X3 (electric motor 2-pin) connector from the transmission control unit (TCU).
Check the electric motor power circuit. 1 2 06/01/2004 f544485 X3 Check for voltage between pin 1 (power circuit 232) of the X3 connector and the battery ground terminal. Voltage drops more than 0.2 volts from the voltage measured at the battery. Repair or replace the wiring as needed. See Section 54.06 , Subject 100. Voltage is within 0.2 volts of the voltage measured at the battery. Go to the next row in the table. Business Class M2 Workshop Manual, Supplement 20, September 2011 301/1