'01 AW50 P0780 + No 4th - Saabnet.com Bulletin Board
This '01 SE has been sitting for a few years, nobody knows why.
On the 28th, I took it from its resting place on a 45 mile drive. All surface streets, but 25-50mph. Very little throttle input as the tires were shot. But a fair, long drive.
The transmission fluid was straight black, so I changed it using Valvoline Maxlife. It's good fluid, meets the specs. Only one change. Did some other stuff - new PCV, checked the oil pan, replaced the tires. Basic rehab stuff, nothing further with the transmission.
On the 5th I took it out for a drive. After about twelve miles of low-speed surface streets I decided to hit the freeway. At the top of the on-ramp the car did not shift into 4th as expected, and the CEL and gearbox light came on. The transmission *seemed* to shift normally, just no 4th gear. Got home, codes stored were P0713 (no temp signal) and P0780 (downshift fault).
A little investigation revealed that there was some damage to a cluster of wires around the coolant reservoir - three wires damaged, the two for the reservoir (fixed my low coolant light!) and one for the trans temp sensor. It's weird that in a 45 mile drive it never developed a fault, not even for the trans temp sensor which was OBVIOUSLY disconnected! In any case, I repaired the wires, did a second drain & refill with Maxlife, and hit the road again.
Similar scenario - shifts fine R,1,2,3, but when it's supposed to shift into 4th CEL and gearbox fault. This time, no P0713 (fixed!) and a P0780 (general mechanical fault). I repeated this about a half dozen times - cycling the key and resetting the code each time. On the last attempt, I got stuck in limp home mode... but in 3rd instead of 4th because there is no 4th gear. LOL?
Took it back home, ran through the activations in Tech 2 - cycling the 1 and 2 shift solenoids and the lockup solenoid. No faults recorded, but setting Tech 2 to autorepeat 10 or 20 times does not net me 10 or 20 clicks. Like five or eight. I can't hear the lockup solenoid - possibly only because I lost my stethoscope.
I don't have a history on the car - maybe it was parked and the transmission developed a problem, maybe the transmission developed a problem and it was parked. I don't have any slipping - in gear, it behaves at it should. In fact, in limp home mode, stuck in 3rd, it slipped an appropriate amount even under heavy throttle. I'm not good at automatics, I lack any test equipment. If I take it to a shop, I'm going to quickly eclipse the cost of just replacing it - maybe just with diagnosis, but certainly if any parts are ordered.
The three things I'm thinking about:
1. Put an additive in there to see if some increased viscosity changes behavior
2. Replace the three solenoids - they're cheap, about $30 each
3. Junkyard an entire valve body - I think statistically that'd work out ok :)
4. Get to replacing the transmission
Anyone have any thoughts or guidance?
posted by 12.195.130...
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