Need Advice: Facing a TCU failure in my Maruti Baleno CVT

In fact, they are pushing me to go for the TCU replacement. Now that the car is out of warranty period, the cost will be on me.

BHPian Livnletcarsliv recently shared this with other enthusiasts.

I am now in a serious show-stopping situation with my Maruti Baleno Delta CVT model.

It's a 2018 model with approx 28,000 on the ODO. Single-owner.

Two days back when I started to drive my car from my parking, I was unable to move. When I called my FNG mechanic, he said there is an issue with the gearbox. He recommended I take the car to the nearby ASS since he doesn't have experience dealing with the CVT gearbox, which I felt was very genuine and appreciable.

Now, the car is with the ASS and they are saying that it is TCU failure. They are asking me to replace the TCU completely for which they are quoting me around Rs 60,000.

I wrote to Maruti and now everyone (myself, the dealer and the OEM) is on the discussion table and still, they haven't diagnosed the cause of the TCU failure. In fact, I did ask for the error codes but they haven't shared / revealed yet. They mentioned about 3 errors - range (DTE) sensor error, outside temperature error and TCU error.

In fact, they are pushing me to go for the TCU replacement. Now that the car is out of warranty period, the cost will be on me. And I don't think it is a good idea to claim insurance as well (since there is no external damage to the car).

What should be done?

Here's what BHPian vigsom had to say on the matter:

This is weird. I just can't accept the argument on the TCU. I haven't heard of a Transmission Control Unit needing replacement unless, of course, the unit was exposed to high voltages OR water. Please recall of any incident or some work that was done just before this failure viz. one day it was working fine, but something happened and the next day it stopped working. The issue could be due to one or more of the following:

• Rodents clipping some wires
• Transmission running low on oil
• Wrong oil filled into the transmission (if the transmission oil was replaced sometime in the recent past)

Possibility #2 can be verified by removing the transmission oil dip stick and checking the oil level when cold.

I have heard of a Toyota Corolla with a torque converter AT not move and the transmission "fuming" due to low oil due to a leak. The moment the right grade oil was topped up, it was all fine.

Here's what BHPian saikarthik had to say on the matter:

The DTC list will give us more clarity, but sensor fault for DTE (fuel level sensor), outside temperature, TCU fault can't occur all at once and how will replacing the TCU alone will solve other two? Because the TCU is not related to either of these sensors. Only probable connection might be a common power cable at fuse box and that too is rare.

So, better to check the wiring manual at ASS. Remove the TCU (if not integrated into transmission) and connect to a different vehicle if available in service centre. If it works there, then TCU replacement idea can be trashed. If no vehicle is nearby, or TCU is integrated on transmission, then remove the TCU connector, check fuses, connect back and try doing battery terminal disconnect too. I hope battery is at good voltage level.

Here's what GTO had to say on the matter:

This thread also serves as a reminder to all of us to take the maximum extended warranty coverage available. Today's cars have too many expensive electronic parts (as seen in this very thread) and even Maruti's bills can be exorbitant. 60 grand is a lot of money! Just take the 5 - 7 year warranty offered by the OEMs and sleep in peace.

Hope things work out for you, Livnletcarsliv.

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