Sentric

Vehicle info:
2001 Grand Cherokee Laredo
4.0 Litre
Trans has the FullTime 4WD option (not sure how many trans options there are)

Issue:
Overdrive will not engage, no dash lights (CEL) currently, there was one but the battery was off for a couple days and the light is still off after driving about 50 miles.
Driving at 70mph it sits around 3k rpm, this happens when hot and cold.
Pushing the O/D button turns the dash light on and off but does not engage/disengage.

Pending code: P0783

Attempted Remedies:
New TPS and new Output shaft speed sensor, ATF is not low.

dave1123

The P0783 code is for the overdrive solenoid. Why would you change the TPS and speed sensor?

You have a 42re transmission and the NP247 transfer case.

Sentric

I should note that it's not mine, it's my boss's WJ. We had read common remedies for the issue and he tried those because they were cheap parts replacements. I just found out that it was throwing a CEL when he dropped it off at my house for me to look at.

So basically it's the shift solenoid and I'd have to drop the pan and it's right inside the trans?

EDIT: Also thank you for IDing the trans

dave1123

Yes, there is a solenoid pack on the front of the valve body containing the overdrive and converter lock-up solenoids. they are sold as a pair. You might as well install a new filter and change the fluid while you're inside it. Mopar has a reusable pan gasket that's a neoprene and steel sandwich that requires no sealant and can be used many times. It's well worth the price.

It's been so long since I did mine, I don't remember if you have to drop the valve body or not.

SteveMongr

Full-Time as well as Part-Time, 4-Low and 2-Hi ?

dave1123

No, I'm thinking he has the 247, 4hi and 4lo. It's a 249 with a better gerotor clutch instead of the VC.

Cherryokee

I'm thinking that - if it's your boss's vehicle then you should be playing stoopid as-if you don't know enuff about trannies. Even with the best of intentions, there's way too much that can go wrong there - if you know what I mean...

dave1123

Hummmm....good point Cherryokee! It could be something as simple as a broken wire in the plug. My reverse lights went out because of a wire that broke off at the plug. The rest of the NSS still worked.

BTW, harness plugs can be gotten from a dealer, usually must be ordered.