Trafic transmission slipping and erratic shifting

Experiencing severe transmission issues with my 2005 Renault Trafic diesel. Shifting isn't possible with the paddle shifters, the gearbox slips and shifts erratically, and there are grinding noises during gear changes. Paddle shifters are slow, and the gearbox is often in emergency mode. Error codes are stored. I suspect a defective transmission control unit. Any insights?

4 comment(s)

I had similar symptoms with my Trafic. Slipping, unclean shifts, and emergency mode point towards TCU issues. Have you checked for specific fault codes related to the solenoids or sensors within the transmission? It's worth investigating the wiring harness and connectors as well before condemning the entire unit. A faulty connection can mimic a defective control unit.

Thanks for your reply. I haven't checked the wiring harness and connectors yet, but that's a good idea. What specific fault codes did you encounter when you had this issue?

I wish I could give you the exact codes, but it was a while ago. It's very likely you're looking at a faulty TCU though. Given the symptoms and the fact that you already suspect it, I'd recommend taking it to a workshop equipped to diagnose automatic gearboxes. They will be able to use diagnostic tools to pinpoint the problem and confirm whether the TCU is indeed the culprit. If so, be prepared for a replacement, which can be costly.

Thank you for the advice. I took it to a specialist workshop and, as you suspected, the transmission control unit was indeed defective. The repair cost came to around 1000€, but the van is now shifting smoothly again.

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