The 2003 Sienna with 180,000 miles starting slipping in and out of neutral while driving. It can go for several days with no problems then start up again, no rhyme or reason as to when this happens. It started several days after the left rear shock broke, not sure whether this is relevant or not. I cant seem to get any certain answers as to what is causing this from the Toyota Service Dept, just a very broad span of answers that could turn into a huge repair bill. Thank you for your time.
Have you checked your transmission fluid lately? A good, independent transmission shop can check out your transmission thoroughly and give you answers to your questions. Have them check the transmission linkage/cable to make sure that each detent is correctly selected when shifting. Shifting between detents can cause the transmission to suddenly shift into neutral at random times.
It was first taken to a transmission repair shop and I was told after he kept the Sienna for several days that it needed to go to the dealer, and I should clarify that it doesn’t stay in neutral it slips in then back out so your speedometer and odometer go up and down when its “acting up”.
Since the transmission shop said it needed dealer attention…I would take it to another dealer for a second opinion.
So the dealer says u may have several issues that might include a major expense? And u prefer to take it to a place that will charge less but still fix it? Good plan
Since the speedometer is going up and down, the transmission control module is going to have a hard time controlling the gear selection. Since the Vehicle Speed Sensor reads the transmission output shaft speed and the truck is not varying road speed or wheel speed radically, that is the system that has to be looked at.
After a closer look at the VSS schematic for your vehicle, I found that the signels from the ABS wheel sensors go to the ABS ECU module. The ABS ECU module sends the signel to the speedometer head. The signel is amplified and sent to multiple units including the Engine Control Module which would also be controlling the transmission.
Since you have recently had work done on the left rear shock, I would have the dealer look at that wheel sensor and see if there is a problem i.e. misplaced sensor, damaged wiring, corroded connector, etc. The good news is that the transmission is probably going in and out of ‘limp home’ mode and is not damaged.