Troubleshooting
Toyota Stand-Up End Control Service Manual
Power Amplifier Fault Codes
Power Amplifier Start-up Procedure: The following is a description of the sequence of events which occurs regarding the power amplifiers when the truck key switch is first turned ON. 1. The truck must complete a series of internal checks before any tests of the power amplifiers are started. 2. Once the internal checks are complete, the voltage at the output side of the TPC contactor must reach at least 32V before the amplifiers can be turned on. This is referred to as “precharging” because the amplifiers have large capacitor banks which must be charged prior to closing the TPC contactor, or they may be damaged. This precharging is done by the amplifiers themselves and starts when the truck key switch is turned ON. If precharging does not happen within 5 seconds, a “Waiting For Precharge” message will be displayed. Note that since both amplifiers are connected in parallel, one amplifier can precharge both amplifier's capacitor banks. See Waiting For Precharge Message on page 5-3. 3. Once precharge occurs, the amplifiers will be run briefly with the TPC contactor open in order to verify that the TPC contactor is not welded: a. First, the amplifiers are activated by turning on the KEY and EPO outputs from the Translator card to the amplifiers. There are LED indicators on the Translator Card which illuminate when these lines are turned on. See Figure 5-2. The amplifiers must respond to this by turning on their respective TPC_x output (TPC_L for left amplifier, TPC_R for right amplifier). NOTE: KEY_ON and EPO signals are generated by the Translator Card when the TPC contactor is energized and are not connected to the truck key switch or EPO switch in any way. If an amplifier fails to turn on its TPC_x output within 1 second, an error code “2M” and/or
5-6
“HK” will be displayed on the operator display. b. Once both amplifiers have turned on their TPC_x outputs, the DM (deadman) output from the Translator Card will be turned on next. This signal also has an LED indicator. c. Next, one and only one direction command signal line will be turned on for each amplifier. These direction signals each have an LED indicator and are named as follows: • FWD_L - Forward command to the left power amplifier • REV_L - Reverse command to the left power amplifier • FWD_R - Forward command to the right power amplifier • REV_R - Reverse command to the right power amplifier The left forward direction line will always be turned on, but the right amplifier direction line will changed depending on how the steerable wheel is turned: If the wheel is close to straight, the right amplifier will be set to drive reverse. If the wheel is not close to straight, the right amplifier will be set to drive forward. This will cause the drive wheels to always drive against each other during SelfTest. d. Once the direction lines have been set, a small throttle command is sent to each amplifier. The amplifiers must then pull down the TPC contactor output voltage down sufficiently to verify that the TPC contactor is open. If this does not happen, a fault code “44” will be displayed on the operator display. e. The amplifiers are shut down when the TPC contactor output voltage drops down sufficiently or when 0.6 seconds elapses, whichever comes first.
00700-CL1SM-3 Issued: 6/1/04