Intermittent AT Check warning light

[AdiGri]

Hello folks,

I bought this sick puppy at half price (2008 M35, base) with a few issues, but willing to spend some cash to fix it. The car was involved in a frontal crash before and they rebuilt it but some problems remain, though it runs fine as far as I can tell.

The first one (it may be bad), is the AT Check warning light, typically is on but when I drive, randomly goes off (and on again). When the warning is off, the gear indicator shows D while when the warning is on, it shows 4. Here is a little video that shows what happens: https://youtu.be/ORn1rI9yBf8]. The AT indicator assembly is missing the shift lock switch:


Where I live there is no Nissan/Infiniti dealer to diagnose this. The shop I've been to said that as far as they can see, there is a problem communicating with the AT shift control system. Could it be a bad connection? The shift control system is not that cheap ($300+) and I wouldn't want to buy it without being sure that it is the source of the problem.

The second serious issue is the fact that the car mileage indicator is not working, being stuck at what probably was the mileage at the time of the crash. Again, I wouldn't mind buying a new speedometer assembly ($400+) if I would know it would fix the problem. The trip computer works, so the miles are being sent, however not to the mileage indicator. I'm thinking of removing the dashboard and see what's connected and what's not.

The third issue is the AFS indicator that keeps flashing "Off", regardless of the AFS switch position. I'm suspecting that is probably again something that something is not plugged in properly.

So, any thoughts on any of these? I would appreciate any advice.

[Ilya]

I think you have the right idea, I'd check all the plugs (and possibly voltages, etc. to make sure wiring is good while you're in there). Sounds like they either didnt' replace some parts (sensors) or didn't plug them in after they fixed the cosmetic stuff.

You can get the FSM for your car in my HowTo link in the signature.

[Brian35XR]

The AFS light could be due to them not replacing the car with AFS lamps after the front end crash causing it to be permanently off?

Do the headlights turn left and right when you turn the wheel?

[AdiGri]

As far as I can tell, the lights don't turn. I'll try to check the part number for the headlights and see if they are AFS or not. Ironically, it is the flashing of the "AFS off" warning that bothers me the most - I can live without AFS, though I would like it fixed.

[EdBwoy]

Man, that transmission issue is a curious one. Seems like you sometimes lose overdrive when you hit the gas and it tries to downshift to 4th.
Out of curiosity, is the shifter notchy when you shift it from D to the manual side on the left? In that can you accidentally bump it to the left or does it require some effort?

Also, when driving in manual mode and you up shift all the way to 5th, does it show the same symptoms at speed as while in D?

Fluid level good?

[AdiGri]

Switching to manual seems normal (no effort, no bumps or any other unusual thing). However, the manual mode does not seem to work (it makes no difference if I move the knob to "manual") and gear 4 is the only one displayed (regardless of how I attempt to change it). I hear the gears changing when I drive, however it does not reflect on the dash - it shows 4 all the time, except when the AT Check turns off (then it says D, even when the switch is on "manual"). I'm buying an ODBII scanner to see if the gears change up to 5 - though according to the service manual it seems that it will switch to 5 only at 120 mph. I'm not sure if it's the A/T Shift Selector that's messed up (see the picture above) or the A/T shift selector assembly itself.

I'll check the fluid asap.

[EdBwoy]

I'm a little worried if I am interpreting this correctly.

Switching to manual seems normal (no effort, no bumps or any other unusual thing). However, the manual mode does not seem to work (it makes no difference if I move the knob to "manual") and gear 4 is the only one displayed (regardless of how I attempt to change it). I hear the gears changing when I drive, however it does not reflect on the dash - it shows 4 all the time, except when the AT Check turns off (then it says D, even when the switch is on "manual"). I'm buying an ODBII scanner to see if the gears change up to 5 - though according to the service manual it seems that it will switch to 5 only at 120 mph. I'm not sure if it's the A/T Shift Selector that's messed up (see the picture above) or the A/T shift selector assembly itself.

Do you have another m35 or M45 to compare and see what normal shifting feels like? It's hard for words to convey what I am trying to say here, but moving the selector over to the manual side should not be an effortless exercise. It almost feels like shifting down from N->D, in that you feel like you're going over a hump then the selector slides into gear.

Going to your first post, the shifter bezel is indeed missing the shift lock trim cover, as is normal for a car with a dead battery. Hopefully the people that moved the car utilized the shift lock switch before attempting to yank it around thru the gears. I am led to suspect that the gear selector assembly might be physically damaged. If- and that's a big IF- your fluid level is good, the selector just easily slides to the manual side, and the manual gears will not go up or down, then it is not really engaging the manual mode... but yes the AT will still shift thru the gears automatically.

From your video, I assumed the car was just randomly popping the light and dropping to 4th with no human intervention. I also believe the trans shifts to 5th at speeds lower than 120. I have to refer to the manual again to verify, but my experience is that when I'm at speed, say 60mph, then I bump the selector over to the left, the screen display changes from D->4 and you see the RPMs rise - meaning it previously was on 5th.

Try driving the car and pushing the selector to the right while it's in D and see if it still "slips" into 4th. Do the RPMs rise if you manually try to move it and hold it to the left?

[AdiGri]

Unfortunately, I don't have access to another M. The gears shift as expected (when the RPMs reach about 3k and then drop under 2k). However, the dashboard only shows 4 (in the last days, the AT Check doesn't flicker anymore, just stays solid and the gear display shows 4, even on idle). It shows R on reverse, or N in neutral, but the moment I move the switch to D it displays 4 (nothing else), regardless if it is in automatic or manual mode. Moving the stick to manual feels indeed like moving from N to D, not too hard, not too soft. In manual mode, going + or - doesn't make any difference (the display still shows just 4) so I'm assuming that it never actually goes on "manual". Changing to manual while driving doesn't seem to result in any change in RPMs or gear shifting behavior and it will still shift in the higher gear if I accelerate.

[EdBwoy]

With what you said, it sounds like the selector is physically ok. Not too hard, not too soft.

... However, the dashboard only shows 4 (in the last days, the AT Check doesn't flicker anymore, just stays solid and the gear display shows 4, even on idle). It shows R on reverse, or N in neutral, but the moment I move the switch to D it displays 4 (nothing else), regardless if it is in automatic or manual mode...In manual mode, going + or - doesn't make any difference (the display still shows just 4) so I'm assuming that it never actually goes on "manual". Changing to manual while driving doesn't seem to result in any change in RPMs or gear shifting behavior and it will still shift in the higher gear if I accelerate.

The part just quoted above makes me feel it never goes into 5th. Maybe you could count how many times it shifts from 0-60mph under conservative driving. Maybe the M35 guys can chime in and tell us what to expect for RPMs vs gear# at certain speeds.

I don't have my M with me but here's a typical scenario:
Cruising along at 60mph. Smack the lever to the left, the RPMs jump up and the dash displays 4th. As you slow down, the gears drop on the dash until 1st gear. When you take off again, the engine revs to hell to remind you that you have to manually upshift to 2nd,3rd,4th and even 5th.
Now what you're saying is that yours will upshift by itself regardless. It's like you've got a hybrid situation where you put the selector to D but it immediately goes to manual; yet it still uphifts like it's still in D mode....Kinda like having an overdrive switch off letting you know you can't go past 4th.

Was the fluid level ok as far as you could tell?

[AdiGri]

I'll have to check the fluid level - it's not that easy to reach though . But would a low level of fluid cause such problem?

[EniGmA1987]

The third issue is the AFS indicator that keeps flashing "Off", regardless of the AFS switch position. I'm suspecting that is probably again something that something is not plugged in properly.

I dont know about your other issues, but the AFS flashes when the system is failed. So like you said it could be that something is unplugged, but it could also be that when the front was rebuilt the person doing it did not buy the AFS model headlights as they cost more. If the headlights are the basic model then that would be why the AFS system is not working and flashing at you. Or maybe the headlights AFS motors are broken. Headlights are crazy expensive, so it probably is not something you would want to fix if the wrong lights are already there and working fine.

though according to the service manual it seems that it will switch to 5 only at 120 mph.

The car should auto change into 5th gear when in normal drive mode when you get somewhere between 50-60 mph. It should definitely be in 5th gear all the time when cruising on the freeway. Someone else could probably tell you what their RPMs are at 65mph and then you can see if your car is the same or higher, then you will know if you are in 4th or 5th. I would, but I dont have the same gearing as you so my RPMs are different.

[AdiGri]

I'll see if I can figure out the AFS thing - one way or the other, I have to get rid of the "AFS Off" flashing, it's quite distracting, maybe I'll disable it in the dashboard? The lights are indeed very expensive (and in my case, I have to add 50% duties on any car parts - still better than 85% for cars over $10k).

I'll record how the gears change from 0 to 80 MPH - maybe it does go into the 5th. Anyway, I have a feeling that the AT shift selector assembly will have to be replaced.