aaronschmidt73
DMax Automatic Transmission Implausible Shifting
Summary of the thread
The 2019 Chevrolet DMax diesel is experiencing issues with implausible shifting, a transmission warning light, and rough shifts, sometimes feeling stuck in emergency mode. The hydraulic fluid level is fine, but the oil may be worn out. A minor electrical issue with a faulty sensor causing undervoltage is suspected to affect the transmission's electronic control, leading to these problems. It is recommended to check the transmission fluid condition and address the undervoltage issue, which was confirmed as the cause, leading to a repair and oil replacement.
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4 comment(s)
aaronschmidt73 (community.author)
Yes, by emergency mode, I mean it seems stuck in a higher gear, limiting acceleration. I did have a minor electrical issue a few weeks ago – a faulty sensor that was drawing too much power. Could that undervoltage mess with the transmission?
finn_schwarz82
Absolutely! Modern automatic transmissions rely on electronic control. That faulty sensor could very well be the culprit. The transmission control unit (TCU) needs stable voltage to accurately control the solenoids that regulate oil flow and pressure. Erratic voltage can lead to the symptoms you're describing – the TCU gets confused, resulting in poor transmission performance and eventually triggering emergency mode. It might be worth getting the transmission fluid condition checked professionally, but I strongly suspect undervoltage could be the reason. A workshop visit is highly recommended.
aaronschmidt73 (community.author)
Thanks a lot for the insights! I took it to a workshop, and you were spot on. Undervoltage had caused the automatic transmission oil to wear out quicker then expected, leading to the issues. The repair, including an oil replacement, cost me around 240€. I appreciate your help!
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CHEVROLET
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DMAX
finn_schwarz82
Sounds frustrating! Implausible shifting with the light on can point to several things. Since the hydraulic fluid level is fine, a leak is less likely. When you say 'emergency mode,' do you mean it's limiting you to a specific gear? Has there been any work done on the electrical system recently? Undervoltage can cause glitches with the electronic control of the automatic transmission. Automatic transmissions rely on specific oil pressures and flow rates, and undervoltage can affect those. Slipping transmission can also cause those symptoms.