Automatic Transmission TCU Issue
 

2015 FR-S, 55,000 km, completely stock, and serviced religiously at Toyota.

Starting my day today like every other day. Got into the car, started it. Shifted into D -- huge jerk/lurch, not smooth at all.

Moved a few metres out of the garage, turned off the car and tried to start it again to see if it helps. Car does not start -- no cranking at all. Turn it off, pulled the key out, and retried a few times. Finally car started again, but noticed the lights on the floor shifter (the PRND lights) are gone, and the gear info on the dash is also gone (usually it says P, R, N, D, and which gear in manual mode; it's just blank). Again huge jerk shifting into D.

Thankfully, dealer is just 1 KM again, so I drove slowing straight there. Also noticed the paddles don't work.

It's almost like the car didn't know a transmission existed.

The dealer said the it's a "neutral lock issue" (?). A new TCU replacement is required. No fuses are blown.

The good news is it's covered under the transmission/engine warranty. The bad news is Toyota Canada dealers are having logistic issues getting parts, and the new part may take up to 3 weeks to arrive; driving the car in the mean time is not recommended to avoid mechanical damage.

Asked for a loaner, but was told they may not be able to -- but will bring this up to the manager.

You might check to see if the TCU is tightly bolted down (grounded properly).


humfrz

Good point, though I have left the car with the dealer, hope they check that!


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Finally got the car back fixed. Turns out it was the the neutral safety switch.

The strange thing is, after installing a new one, the issue reoccurred. The new switch was getting hot to the touch, and at the same time, the fuses were blowing out. The techs finally replaced my LED reserve lamps (which I had installed for 4 years) with standard bulbs and voila, no more issues. The LED bulbs must have started to short out or something -- they were starting to flicker intermittently last time I looked at them.

Anyway, just wanted to shared my exlerience here in case someone else has the same issue.

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I’ve been told led bulbs can cause issues with canbus systems

What/where is a reserve lamp? I've changed out every light on the car to LED from headlight, head lamp, side marker, plate light and tail lights.

Oh ha ha...reverse lights. Yeah I changed those to LED too. If it helps any I used these: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
and they've been in there for 2.5 years. Crazy bright on the reverse camera looking back there, it's like a spotlight when backing up.

Good to know since the only LEDs I have installed are in my reverse lights.

So did the LED lights cause the initial problem too?

I had mine on for 4 years, until the issue happened...


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Not 100% sure, but given that the issue reoccurred with new neutral safety switch, but when away once bulbs replaced, sounds like it did.


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I have had all my lights swapped to LEDs. But then I installed Toms tails and it freaked the car out. When I hit the signal even my radio was blinking lol. Had to remove the LED from my corner lights and it went away.

So yeah, it can happen.

When I installed LED lights (before I added a resistor) they blew my STOP fuse. It took me awhile to figure out what had happened.

Without a similar resistance to the OEM bulbs, LEDs can cause weird issues...