GM calls the "Direct" clutch the Overrun Clutch, it is located in the overdrive section of the 4l30e. The 4th clutch also called the Overdrive Clutch is located in the overdrive section. When the gear selection is Reverse or 1st or 2nd or 3rd gear the Overrun Clutch is applied and overdrive section planetary gear set drives the transmission at a 1 : 1 ratio. When the PCM commands 4th gear the Overrun Clutch releases and the Overdrive Clutch applies, the overdrive section planetary gear set drives the transmission at a 0.723 : 1 ratio.

If your transmission does not slip in Reverse or 1st or 2nd gear it is not likely the Overrun ("Direct") Clutch is slipping/cracked.

What happens if the transmission is placed in Drive with Winter Mode selected?

 

Hi mate,
Thanks for the reply.
I'm not sure what Winter Mode is. We here have Economy and Power Modes. In either there are no issues with taking off or slipping. Reverse, 1st and 2nd gear are fine. Just the change from 2nd to 3rd gear is the issue. That's why I thought it may be a solenoid problem.

 

If it feels like a shift into Neutral instead of 3rd gear the 3rd clutch is slipping.
Both shift solenoids have to be working to select 2nd gear.

Btw, there are five friction clutches; Overrun, Reverse, 2nd, 3rd and 4th (Overdrive). There is also a friction clamp called the reaction drum brake band. Some shop weenies call it the High/Low band or the Reverse/1st band. What ever they call it, it is applied in 1st and 2nd gear and since you don't have any slipping in 1st or 2nd the reaction drum brake band is OK.

 

Yes, feels like it goes into neutral instead of 3rd gear.
Does this mean I'm up for a rebuild?

 

To produce the 3rd gear ratio, the 2nd clutch frictions drive the transmission planetary gear set long pinion gears ("planets") using the 2nd clutch drum ring gear and the 3rd clutch frictions (assisted by the unidirectional sprag mechanical clutch) drive the planetary gear set short pinion gears. This locks the gear set and the planetary carrier and tail shaft rotate in the same direction and speed as the 3rd clutch drum producing the 1:1 3rd gear ratio.

If the 3rd clutch frictions slip at the 2-3 upshift the torque from the 2nd clutch causes the short pinion gears to rotate in the opposite direction, this causes the unidirectional sprag mechanical to unlock, which in turn, disconnects the 3rd clutch from the planetary gear set causing the vehicle to slow down. As the vehicle slows the PCM reconfigures the shift solenoids for 2nd gear causing the brake band to apply. When the brake band applies it puts the transmission back into 2nd gear because the 2nd clutch is still applied.

If these words and music describe what is happening with your transmission your looking at a very expensive rebuild.

 

Fair enough.
It does not happen all the time though, 90% of the time it is fine and changes through with no issues.

 

How dirty was the ATF when you drained and replaced it?

 

To be honest it wasn't too bad, dark but not too dark. I have a mechanic that did it for me and I was watching all through the process. As I said earlier, it's booked in on the 7th for a diagnosis. Buggers me! I have noticed though that it seems to happen when I'm going down hill?? It sounds silly I know!

 

This new info you provided indicating that the transmission works correctly most of the time and that it seems to occur when going down hill is not consistent with the 2nd to 3rd gear upshift you originally reported. Maybe you do have a solenoid or shift valve problem.

 

hello i just bought a 99 passport. it slips just out of 4th and overdrive but works in every other gear but does hic up sometimes. im going to read the codes tomorrow 4x4 4l30e i found a 99k miles AT for 450$ 2 hours from me idk if i should go get that one or figure out what is causing it to jump out of 4th and overdrive

 

4th gear and "Overdrive" is the same gear ratio.

The original transmission was a 3 speed, to provide a 4th gear capability a separate assembly was retrofitted to the front of the transmission. This assembly is called the Adaptor case or "Overdrive" case. When the transmission section is operating in Rev, 1st, 2nd or 3rd the Adaptor case ratio is 1:1. To shift from 3rd to 4th the Adaptor case ratio is ratio is switched from a 1:1 ratio to a 0.723 ratio. To make the shift from 3rd gear to 4th gear the Adaptor case Overrun clutch is released and the Adaptor case 4th ("Overdrive") clutch is applied.

If you change the transmission be aware that there a 2WD and a 4WD version and the tail shafts are not the same. Also be aware that the electrical connectors on 00-03 4L30e are not the same as 90-99

When you check the ATF level be aware the engine Must be running.

 

Im in aus to my chexk trans light came on stayed on to turned it off started and ran fine later checked radiator only water put coolant in never slipped again for about a week then got under the car noticed on the passenger side all the wires that come off the trans towards the front were covered in grease and also sitting on the side of the exhaust So i cleaned everything down tucked wires up away from exhaust never slipped untill i drove up the highway doing 100 truck got a bit af a rattle slipped once again but evertime it slips i put from normal to power no probs at all moved wires again no slip so it only seems to happen when wires get are either up agains exhaust or the engine gets hotter than normal which is not often so i put in power fir a while then back to normal runs fine or maybe theres a small shortage in harness ??