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Discussion Starter · #1 · (Edited)
'03 Aero Gearbox Warning Light - RPM Drop, Not in Limp Home Mode

Hey Guys,
As luck would have it, I got all the problems worked out, just to have a new one pop up.

While I was driving today the RPMs dropped slightly and the car felt light I drove over a rough patch of road, like rumble strips. The gearbox warning light came on. I pulled over and checked the fluid levels, they are fine.

The car is NOT in limp home mode. It drives normally, no smells or sounds. The only indication of any kind of problem is the occasional drop in RPM. It only last for a split second, and only seems to happen when you're driving around 45 MPH at a steady pace. I have not noticed it at idle or under acceleration.

The local shop will read my codes tomorrow, but I would like to know what to expect. Unfortunately, I haven't had time to pick up my own TECH II yet, so I'm at their mercy.

Any ideas?
 

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Any OBD code reader will be able to read the codes, you don't need a Tech 2

until then it's hard to say what happened. BTW, remember there are two limp modes. One for the engine, one for the transmission. Those are different and independent. (i.e. you can have one without the other)
 

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Discussion Starter · #3 ·
No codes. Ran a scanner and it came back clean. Just the gear with the (!) in the middle. Other than that and the occasional stutter, no other problems. It starts and runs fine, no message on the SID.

Thanks for the help!
 

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Discussion Starter · #6 ·
OK -

I scanned it again, still said "0 Codes". I pressed "ERASE" on my scanner, and it turned the light off.

Now I don't have a warning light anymore, but I don't know what caused the original fault, or the stutter.

I checked the fluid levels again, they are fine. The color is dark, but not black, it still has a bit of a pink hue. It doesn't smell burnt.

I'm stumped.
 

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Any chance you took the SID out and started the car with it disconnected? That'll cause the transmission to throw an error since it can't see the paddle shifters. But that usually throws a code.
 

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Discussion Starter · #8 ·
Nope. SID has not been removed. I had my drama with the ABS, but that's been over for a couple weeks and no problems until today.
 

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...........While I was driving today the RPMs dropped slightly.................

...............It drives normally, no smells or sounds. The only indication of any kind of problem is the occasional drop in RPM. It only last for a split second,..............
If it was only the symptoms above I would suspect CPS, but...

Regards,
John.
 

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Discussion Starter · #10 ·
I have a new CPS sitting in the closet. I'd put it in if I thought it would fix the issue. I didn't think that the CPS would throw a transmission warning though?
 

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I think that john was talking about the rough running and didn't know what to do w.r.t your car since it threw a transmission error.

I'd keep driving it and see what happens. If there is something really wrong it'll throw an error code.
 

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Discussion Starter · #12 ·
That's the plan. My wife drove it today and it did the stutter again, but no error light this time.

I'm thinking a flush and fill might be in order just to make sure it has the proper fluids in it. The previous owner was not very thorough in his record keeping. Is that something worth doing myself, or is it better to take it to a shop?
 

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Easy to do yourself, get a case of oil (Toyota IV or Mobil 3309), drain, fill, drive 20 minutes or so, repeat twice and you're done.

If the oil is still nice and red on the first drain don't bother with the second and third. If it's black then go ahead and do it.


The plug is right on the bottom of the transmission, you fill through the dipstick (unless you have a later car then you take out the plug where the dipstick should be. Make sure you can get the plug out before you start to drain!)
 

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Rumble strips = torque converter?

I had this EXACT issue on a different vehicle, a 2005 Nissan Pathfinder.

It would hit a certain RPM, I think around 1500 - 2000, then the RPM gauge would get weird, and the truck would "rumble" -- exactly as you described, it felt like I was going over rumble strips. If I gave it some more gas, the issue would go away. It would occasionally start rumbling off and on at cruising speeds, too.

The Pathfinders had an issue where coolant would leak into the transmission fluid because of a defect in the transmission cooler lines. So coolant was getting into the tranny and eating up all the seals and other sensitive bits. I don't remember the technical details, but it messed up the torque converter to the point where it was having trouble locking up when trying to engage, which resulted in the rumbling sensation.

I haven't heard of this issue on Saabs. BUT, it may be worth it to check if the tranny fluid looks like strawberry milkshake. And you can't just check it from the dipstick. On my Pathfinder, the fluid in the dipstick looked fine, but when my mechanic drained the tranny fluid from the bottom, it was like a strawberry milkshake.

It may not be what you're experiencing, but may be worth a check, since the symptoms you're describing are EXACTLY what I went through on my Pathfinder.

I hope this isn't the case, though, because it means your torque converter is shot.

EDIT: It may have actually been a defect with the radiator, now that I think about it. Bottom line is coolant was getting into the tranny, which is BAD.
 

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Don't waste your money on a shop. Easy enough to do yourself.
-Get under car (ramps or jack with stands)
-Remove drain plug
-Replace plug after fluid has stopped
-Fill with appropriate fluid (Toyota type IV, Mobil 3309, etc...)
---DO NOT OVERFILL---
-Check fluid per instructions
It's something easy that anyone can do.
 

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Discussion Starter · #17 ·
andybisnut -

Thanks for the info, I hope that's not the case, but it gives me something to go on. When I drain the fluid this weekend I'll see if it looks milky (crossing my fingers that it doesn't).

Dosmie & Unclemilte -
Thanks for the write up, seems easy enough. I managed to change the alternator so I think this should be easy enough. I'll swap the fluids this weekend and let you know what I find.
 

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Discussion Starter · #19 ·
Update - New Issues

Hey Guys -
Small update. My wife drove the car yesterday and all of the lights I fixed last week came back on, ABS/BRAKE//!\ and TCS off. She turned the car off and they were out next time we started it.

The RPM drop only seems to happen at 45 MPH, I haven't noted it at any other speeds.

There are now no warning lights at all, and the engine shows no codes.

This weekend I'm going to try:

Trans Fluid change
Clean MAF
CPS Sensor Swap
Vacuum Hose Change

Anything else I should add to the list?
 
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