valentinawilson8
RCZ Automatic Transmission Shifting Issue
Summary of the thread
A 2014 Peugeot RCZ diesel's automatic transmission was experiencing shifting issues and entering emergency mode, with diagnostics indicating a potential undervoltage problem. Possible causes included bad solenoid operation or corrupted data to the Transmission Control Module (TCM) due to undervoltage. Suggested solutions involved checking the charging system, battery, alternator, wiring, and ground connections. Ultimately, a workshop identified worn transmission oil as the issue, likely exacerbated by voltage fluctuations, and a transmission oil change resolved the problem.
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4 comment(s)
valentinawilson8 (community.author)
Thanks. I checked the battery and alternator, and they seem okay. Could voltage fluctuations, instead of steady low voltage, cause these intermittent transmission faults? How would I diagnose these voltage drops?
emiliaheld8
Fluctuations can cause issues with sensitive electronics. Get a diagnostic scan with a tool that can monitor live data from the TCM. Watch the transmission input and output shaft speeds, solenoid signals, and TCM voltage. If it keeps happening, get it to a workshop that knows automatic transmissions.
valentinawilson8 (community.author)
Thanks for the advice. I went to a workshop, and they said the transmission oil was worn out, which they blamed on the voltage fluctuations, even though it's supposed to be 'lifetime fill'. A transmission oil change (240€) fixed it. It shifts normally now, and the error messages are gone.
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PEUGEOT
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RCZ
emiliaheld8
Undervoltage can mess with modern cars and their electronics. Your symptoms sound like transmission issues from bad solenoid operation or corrupted data to the TCM. Before blaming the transmission, check the charging system, battery, alternator, and wiring. Also, check ground connections; bad grounds cause undervoltage.