he stuck in 3rd

[flyin280zx]

hi new q owner here. My car is stuck in the limp home mode and ive done the self diag and i got the at check mode. when i put the car in D it will try to downshift or upshift based on the speed. The gear stalk is also out of alignment and will not slide into 1st or 2nd and the 1st gear switch is missing a wire closest towards the engine. I can not find the 1st gear switch listed in the fsm if u know were it is listed please let me know. Any help is greatly appreciated thanks. I JUST WANT MY Q BACK!!!
Modified by flyin280zx at 2:39 AM 2/21/2009

[Infinitiguy19]

Read pages AT-80- AT-81 and AT-108 in the 1994 FSM

here is the 1994 Q45 FSM if you don't have one: http://Nicoclub.com/FSM

Here is a picture of the switch:

Welcome to NICO.

[flyin280zx]

thanks a ton could u repost that pic. Iv had a mechanic tell me that if it is the inhibitor that it wouldnt even start however he could have just been tryin to fleece me. Just want to know so I dont go back there

[Infinitiguy19]

Right the inhibitor switch prevents the car from starting in R, 1,2,3 and D.

But I do wonder if the linkage needs to be adjusted its self.

See page: AT-34 or go here: http://lh3.ggpht.com/_QC8aSbDQ...5.jpg and press the magnifying glass in the right top corner to expand.

Did you just but the car?

Did you get a box of receipts or the Infiniti Service history?

How do all the fluids smell and look?

[qsiguy]

If the TCU has no power it will stay in 3rd gear regardless of the gear shifter position. This is why we unplug the TCU when we get a dyno performed. Keeps it in 3rd for the duration. Not sure if that helps you or not but your issue could be electronic.

[flyin280zx]

see the vehicle actually had the tcu fuse unplugged before this and it actually drove fine. Is that even possible though . Then the vehicle was impounded and has not ran right since. Unfortunatley it was seriously abused by the previous owner and is currently the cause for most of my electronic gremlings. Thankfully though ive given her a mechanical once over and everything is mechanically in good condition. But so far as infiniti service records go i dont think its been lucky enough to see a regular mechanic let alone an infiniti one.
Modified by flyin280zx at 10:57 AM 2/20/2009

[Infinitiguy19]

Well you sound pretty smart so you should be able to figure it out, But I would then check and see that all the fuses and relays are there and functioning.

[flyin280zx]

Did some more searching and found out that a low charged battery could cause some electrical related problems and with the at check showing on the diag is sound to think that insufficient flow is getting to my tcu could this be the problem or am i just looking for a quick fix. If you also have the oem cca or ca ratings or could you just dispell this illusion from me. The vehicle was sitting for a 2 weeks and was completely dead when i picked it up and has what you would call a local special in it that was just a chemically fresh battery.

[Q45tech]

"Then the vehicle was impounded and has not ran right since"

If you tow a Q with rear wheels on ground, the lack of lube circulation because the engine is not running and turning TC and pump will fry the transmission in a few miles [3-15] depending. Over the years we have see destruction from very short distances of towing.

FLATBED use only unless the drive shaft is removed

[flyin280zx]

yes however it towed on a flatbed and the transmission binding up wouldnt cause the fail safe mode would it

[maxnix]

Was it in P(ark)?

[Infinitiguy19]

Do you mean if the car was pulled by the tow truck in park?

Or if the car was in park while on the tow truck?

[flyin280zx]

I just had a snap on multi diagnostics done and it said that it could not communicate with the tcu. Does any body know if faulty tcus show up as not commincating or if they do I just got a short witch I wouldnt really be suprised about because as I said it does have quite a few electrical gremlins

[flyin280zx]

bump

[maxnix]

Can any SnapOn analyzer communicate with a OBD I TCU?

What does the Consult say?

[MinisterofDOOM]

When my car had issues with the TCU, consult diagnosis showed it as not communicating with the ECU. Definitely get a quick consult diagnostic run. It takes less than a minute.

[flyin280zx]

yeah thats what mine was saying to that either there was a short or open circuit and that the eccm could not communicate with the tcu. And yes it can I said the same thing to the guy and he laughed in my face and said he had a consult for nissans until he bought the 10000 dollars snap on multi diagnostic tool. Doom did yours have to be replaced or was it just an open or short circuit. That and the fact that this my datsun mechanic and one of the only shops in the area that could do the fabrications and understands the word overhead cam.

[flyin280zx]

just out of curiosity are the tcus known for being faulty or what.Seem to see significantly more post about faulty tcus than any of the other os for the q. Is this just a hardware problem or is there a way to fix it. Cause mine just let go without a hint of a problem till one day . Not big on major componets electric crappn out after 160k . I mean my zxt has bout 250k of severe abuse and it was made 26 yrs ago when analog electric signals was the rocket science of the day and was everybody afraid itd kill the sports car. I mean seriously nissan.

[MinisterofDOOM]

The pricetag of the snap-on tool is irrelevant if it doesn't have the proper functions for Nissan computer diagnostics.

I replaced my TCU and it solved my problem. The question that kept me worrying for the first little while after I replaced it, though was why it failed in the first place. I was concerned that there was an underlying electrical issue that damaged the TCU. I've been running the replacement for several months now with no issues at all, though. Still no idea what caused the failure in the first place.

Honestly, when I had my issue, I and others doubted the TCU was the problem as it was essentially unheard of. Mine was the first I recall hearing about. Since then it does seem to be unusually common. Maybe we're misdiagnosing in some cases now that the idea is in our heads? Who knows.

[goody90q45]

Were you able to get rid of the ECU>TCU communications ECU code? and the transmission MALFUNCTION warning? I had these on my black 90Q and could never diagnose the problem even after a TCU swap.

[MinisterofDOOM]

Yeah, all trans-related codes and the malfunction warning in the diagnostic display went away after I swapped TCUs.

I wonder if it was an ECU-side issue with your '90?

[goody90q45]

Darn. I never thought to swap ECU's. I was only thinking about the TCU side of things. I spent hours following the FSM searching for wires and measuring voltages and continuities and ended up with nothing but sore ribs. Too late now. The car's been sold, stolen and is probably on an extended trip to Mexico.