Saturn S Series Sedan SL, SL1, and SL2

No reverse

  #1  
Old 12-03-2018, 12:10 PM
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Default No reverse

I just lost reverse gear in my 2002 sl2 automatic without warning! No slam, no noise. How can I tell if I need a valve body or need to replace the input shaft nut?
 
  #2  
Old 12-03-2018, 12:19 PM
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How many miles on car?
Does 2md gear act normally?
What is the fluid level?

Reverse requires a higher line pressure in the transmission to engage than the forward gears,
 
  #3  
Old 12-03-2018, 12:38 PM
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Default No reverse

110000 miles, fluid level good, 2nd gear seems fine
 
  #4  
Old 12-04-2018, 07:05 AM
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Does the vehicle shift hard ("slam" ) into any gear and if it does /did, did it slam into reverse?
 
  #5  
Old 12-04-2018, 08:19 AM
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Default No reverse

Never slammed ,always smooth
 
  #6  
Old 12-05-2018, 10:53 PM
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Sorry for the delay.

See

https://www.sonnax.com/tech_resources/289-saturn-taat-reverse-issues-should-you-replace-the-valve-body

for a nice explanation of scenarios which result in a no reverse condition. In summary, I'd get a quality rebuilt valve body, a new input shaft nut, but check the VSS first. If you drive it long enough you will eventually need both the valve body and nut. I would take the plunge now if the VSS checks out ok since the parts may not be available when you need them later.
 
  #7  
Old 12-06-2018, 10:23 AM
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Default No reverse

Thanks for the input! I was thinking Iíd probably do both, but not if there was an obvious choice. Itís been a great little car and Iíd hate to get rid of it. My kids have all learned to drive in it and my youngest is almost 16!
Thanks again!
 
  #8  
Old 12-09-2018, 09:11 AM
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Suddenly losing reverse in these transmissions (TAAT MP6, MP7 - these are the ones used in the S series) is most likely going to be the result of a failure of the solenoid valve that controls reverse. A gradual failure could be the valve itself wearing out (valve body) but a sudden failure is going to be electrical meaning either the solenoid isn't getting power (broken wire or corroded connector) or the solenoid itself is either shorted or has a broken winding. It's common for people to go with conventional wisdom and use stop-slip or try the "reverse slam fix" but this is normally a problem that will only be corrected by physically replacing or repairing the faulty part. Fortunately these issues are relatively easy to fix and don't require pulling the transmission or insane acrobatics. If the transmission is allowed to slam into gear though, the input shaft nut WILL work loose sooner rather than later and that will be harder to fix and require a special socket and bracket but still be fixed without pulling the transmission. A sign of the input shaft nut working loose is having no 2nd gear. That's why when someone says they lost reverse the first questions after "got proper amount of correct fluid?" are was it slamming and did you also lose 2nd gear.

That Sonnax link Derf gave you is an excellent source of information and parts on these transmissions. I highly recommend checking them out even if you don't plan on buying anything from them. I fixed my transmission with used parts sourced locally using knowledge gained from their site and this site: Saturn S-Series Transmission Repair Kit - CarSaturn
 
  #9  
Old 12-30-2018, 03:35 PM
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Now Iíve taken the trans cover off and inspected the clutch pack but it seems like the nut is not at all loose! Now what? I watched a YouTube video where it showed the clutch pack wiggly loose, mine doesnít move a bit!
 
  #10  
Old 12-31-2018, 03:43 PM
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It's true that when the input shaft nut works loose the clutch pack will indeed be "wiggly loose". I've had it happen and mine got so loose it was rubbing on the inside of the case cover (to the point it wore completely through). If the nut on the other shaft (with the big gear) is tight then your problem is not likely to be in there. I'm surprised you popped the side cover off already. You had indicated that 2nd gear was working fine so I wouldn't expect to find that nut loose at this time. At least now you know for sure.
An electrical voltage and resistance check at the solenoid valve wiring harness connection would normally be one of the first places to check. I can't remember off the top of my head what exactly the resistance should be across the solenoid coils but they should all be similar values. If you find one that's significantly higher or lower resistance that the others then that would indicate a bad solenoid. The links already given and youtube will have the specifics.
Again, the VSS (Vehicle Speed Sensor) could be the culprit too since the transmission won't shift into reverse if that sensor is reporting a speed greater than 5mph.
I never saw any OBDII codes posted. The OBDII system can actually help narrow down the problem if you can read the codes. I would be very surprised if the SES (Service Engine Soon) light wasn't on. See if you can get the codes and report them here (the code numbers themselves - let us diagnose it here for better clarity).
 

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