Transmission light on

[1990QOwner]

How do I get the transmission light to turn off after I replace the TCU? I just got a replacement TCU and installed it and the light is still on. Thanks in advance.

[Q45tech]

Read the dozen or so causes for [AT CHECK] illumination you'll see most are from a sensor signal internal to transmission or a defect in connections between TCU and transmission.

What is the code? [A-D or 1-9] or multiples

[Haitian_King]

WHAT!? There's a transmission light? I was looking at the dash today while on the highway, praying that no transmission shaped light would turn on and kill my Q and myself in the process. (I have bad luck, and extreme paranoia regarding my Q).

Nothing came on in my display (mine's on the left, I think in 94 they moved the text display to the right.) but OK. Even the Stop Lamp Inoperative message was gone.

I replaced my stock 92 TCU with a 93 and didn't notice anything out of the ordinary other than breakneck acceleration.

What's it mean if it turns on? Does it only activate to signal electrical errors? Or mechanical problems like clutches and worn gears as well?

*Edit*

I seem to have answered my own question.

zerothread?id=247900

[goody90q45]

How do I get the transmission light to turn off after I replace the TCU? I just got a replacement TCU and installed it and the light is still on.

I've been trying to decide which transmission light you're trying to reset. Is it the trip odometer display showing "TRANSMISSION MALFUNCTION", or the orange bar above the transmission/engine looking thing in the display on the right side of the instrument cluster?

If it's displaying "TRANSMISSION MALFUNCTION" I'd first go back and check to make sure the large blue connector went into the TCU straight. If it's misaligned some of the pins may not be making good contact. To be safe try unbolting the connector checking all the pins and then rebolt it back together, keeping it even on all sides as you tighten it down. If everything is good at the connector, and you're sure you've got the right TCU, then you'll need to run the self test as Tech suggested. You can find it in the Transmission section of the FSM. It's a very simple test to perform. Another reason for the malfunction could be a bad TCU. Can you swap in the old one to see if it goes away?

If that orange light is on it's the check engine light (and that icon in the display is an engine, not a transmission). Sorry, I needed to get that little jab in. You'll need to pull the codes off the ECU which is not difficult either if you have a 10mm socket and a phillips screwdriver.

Let us know which warning message you've got and go from there. Are you upgrading from a 1st gear start TCU or going back to 2nd gear start TCU for the winter?

[Haitian_King]

I'm going to check my pins on the TCU. I've had a sneaking suspicion that I did something wrong, but I've been in denial for the past week and telling myself to stop over reacting.

[goody90q45]

What's it mean if it turns on? Does it only activate to signal electrical errors? Or mechanical problems like clutches and worn gears as well?

For peace of mind Reji you should do the transmission self-test yourself. It probably doesn't take all of 3 minutes and it's done in the comfort of your front seat parked in the driveway. Go to the Automatic Transmission (AT) section of the FSM and do the Self-Diagnostic Procedure (without Consult). It's tha first one and depending on what codes you have there are 21 other diagnostics for the transmission.

Every time I do one of these self-diagnostic procedures or programming on my Q I'm amazed at the data the car's computers can hold and the strange ways that the Infiniti engineers came up with to retrieve it. I think it's a great tool that many of us don't use as often as we should if we use it at all.

Both my seat memory lights were flashing last week and I was able to follow the NICO provided instructions (it's in the FSM also) to reset it. Any one else not coming to these forums would have had to spend $100 to have the stealership reset it. Cheers to NICO

[Haitian_King]

I'm going to do the self test, but 96QOwner (i think) said that the self test only tells about solenoids and electrical things and nothing about worn gears/clutch.

So I wanted Keith to do a complete diagnostic. Road test/the whole nine.

[1990QOwner]

Oh man, that is the engine light. I didn't know that until I looked at the FSM. But yeah, I put a replacement TCU in there and it still doesn't start in 1st gear. Does this mean that replacement TCU is bad also?

[goody90q45]

Many people have done the swap and it's a "plug and play", no adjustments required for the upgrade. Recheck the connection and run the self-diagnostic to see what codes come up. Post up the Nissan 10 digit part # and I'm sure someone can tell you which year TCU you have.

[Haitian_King]

The last digits of the first gear start (at least for '93) are 64U20.