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Anastasio, Auto Service Technician
Category: Car
Satisfied Customers: 9
Experience:  8 years automotive diagnostic and repairs experience in all kinds of cars.
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1999 Durango 5.9 L 360 is not shifting into overdrive. I ...

Customer Question

1999 Durango 5.9 L 360 is not shifting into overdrive. I replaced O/D shift solenoid but it didn't help. Any ideas?
Submitted: 11 years ago.
Category: Car
Expert:  Anastasio replied 11 years ago.
First, the obvious , is the o/d light coming on ??
Then check the transmission fuse.. You can also hook up a scanner and pull any codes the transmission may be setting.. Also check your fluid level,   If it feels sluggish in any other gear check and make sure you filter is in all the way.. If you drop your pan and find the filter in the pan that is your problem..
Customer: replied 11 years ago.
Reply to Anastasio's Post: No, the "O/D Off" light does not come on (though there is a button on the steering column to turn O/D off.) I've replaced the fluid and filter. The CEL code that I'm getting is P0783 - which refers to 3-4 Shift malfunction. The O/D unit is separate from the main tranny. The first 3 gears work fine and the overdrive worked fine until I replaced the O/D shift solenoid, so I think the O/D unit is OK too. It seems that the issue is in the link between the main tranny and the O/D unit. That's why I thought the problem was with the shift solenoid. It still may be. While I replaced the solenoid, I left the old wiring harness on there because I would have had to drop the valve body to take it off. The initial problem was that it would shift fine up to O/D when the engine was cold, but it would kick out after the engine warmed up and wouldn't go back in. This is why I changed the O/D shift solenoid. Your help is much appreciated.
Expert:  Anastasio replied 11 years ago.
Loking deeper into your problem ,you either have a problem with the mechanical aspect of the 3/4 shift solinoid(O/D), but being new I doubt it..Or a hydraulic leak where it connects to the valve body.. Or most likely you have a broken wire in the wiring that connects to the solinoid..I really think you should drop the vavle body ... You might also have a leak between the two valve body halves!!
Customer: replied 11 years ago.
Reply to Anastasio's Post: Is dropping the valve body a complex job? Will any springs or parts drop out that I'll have a tough time putting back? As I said, initially it would go into O/D until it warmed up - so I figured the wiring was fine and I left the original wiring in and just changed the actual solenoid. But now it doesn't go into O/D at all. If you think it's not too big of a job and might reveal the problem, I'll drop the V/B.
Expert:  Anastasio replied 11 years ago.
Yes there are check balls and springs , as well as a long proceedure in order to get it off , much less back on again!! Unless you have done it before ,I dont suggest trying it!!But, I guarantee you it's your problem...
Customer: replied 11 years ago.
Reply to Anastasio's Post: Anastasio, Once I drop the valve body, what specifically should I check? Are there any other areas to consider which would cause a 3-4 shift malfunction? Thanks for your patience.
Expert:  Anastasio replied 11 years ago.
Most likely it will be a hydraulic, between the mating surfaces , of the two halves of the valve body...If it heated up, It might have warped.check it with a straightedge and also check the gasket for any tears.Also check the vaves and see if any of them bind when moved back and forth. The slightest binding can cause the problem... Like I said earlier , If you never did this before,I don't suggest it... If you drop something and don't know where it goes ... you know.
Customer: replied 11 years ago.
Reply to Anastasio's Post: Anastsio,
One last thing. Do you have any idea if a bad output speed sensor or torque converter could be the problem? Remember , in the Durango the O/D unit is separate from the main trans. If the main trans is fine and the O/D unit is fine, could it be that there's a bad signal or switch being sent to the control module? One description of the P0783 Code is "No RPM drop @ 3-4 shift" & "The ratio of engine RPM/output shaft speed did not change beyond on the minimum required." Whattya think? Thanks.
Expert:  Anastasio replied 11 years ago.
If you changed the syncro/switch, then if your sensors are reading correctly, It can only be a hydraulic problem.. Especially since you only got that one code..If it was electronic problem,ie.module you would have more codes!! Hope this all helps!!Happy wrenching!!

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