The Astronic ZF transmission in an Iveco Eurostar truck is exhibiting unusual behavior, including delayed neutral engagement and displaying error codes 32 and 154. These errors appear approximately 10 minutes after engine start, initially showing a spanner symbol with code 32, followed by a STOP symbol and code 154. Restarting the engine repeats the cycle. The errors clear and neutral engages once the transmission warms up, which can take up to an hour at 15°C ambient temperature. Warmer ambient temperatures correlate with faster warm-up times.
A previous diagnostic session revealed a temperature sensor within the Transmission Control Unit (TCU) reporting -10°C despite above-zero ambient temperatures. This suggests a potential issue with an onboard temperature sensor. Furthermore, applying heat directly to the TCU’s electronic PCB with a hot air gun allows the transmission to shift into neutral within 3 minutes, without any error codes. This rapid response to localized heating points towards a possible fault within the electronic board itself, such as a cold solder joint or a malfunctioning temperature sensor on the TCU.
While a TCU reset while the engine is running might bypass the clutch test, it’s crucial to address the underlying temperature discrepancy. Error code 32 isn’t documented in the available manual, making diagnosis more challenging. However, the correlation between the reported -10°C sensor reading, the prolonged warm-up period, and the successful rapid engagement after heating the TCU strongly suggests a temperature-related fault within the TCU’s electronics.
Further investigation will involve testing the transmission once it is remounted. This will allow for a more comprehensive analysis and potentially pinpoint the faulty component within the Astronic ZF system. Focusing on the temperature sensor readings and the TCU’s electronic components will likely lead to a solution for the error codes and the delayed neutral engagement.
