Community Forums

wk2 · 04-04-2013, 11:16 AM

I have a 2004 P-32 chassis under a Holiday Rambler coach. The transmission will not "gear down" to gain engine holdback. There should be 3 shift points on the 4 position quadrant, but I get only what seems to be 2--one from Overdrive to Drive and one more that is probably to 3rd gear (whatever, it's clearly not low gear). The shift lever moves through the 3 positions, but there are only 2 shifts.

Does anyone know if the shifting is adjustable?

vtbigdog · 04-04-2013, 12:39 PM

Is it upshifting OK?

The determining factor as to whether a transmission downshifts is engine RPMs. You may want to try those downshifts at a slower speed to see if it works. Accelerate slowly in DRIVE or OD until it shifts into third gear. Then take your foot off the gas and coast and shift the transmission down to the lowest gear you can to see if it goes into second gear. If you feel it go into second gear continue to coast. You may then feel it go into first gear...although you may only be going 1-2 MPH.

max49 · 04-05-2013, 06:04 PM

Your P-32 will go about 35 mph @ about 4200 RPM in first gear. You should be able to force it into 1st gear at 40 MPH or less. You either have a problem or your not recognizing the speed, RPM and gear selection.

wk2 · 04-15-2013, 01:28 PM

Quote:

Originally Posted by max49

Your P-32 will go about 35 mph @ about 4200 RPM in first gear. You should be able to force it into 1st gear at 40 MPH or less. You either have a problem or your not recognizing the speed, RPM and gear selection.

I tried starting from dead stop with gear selector in "1" position. The transmission shifted up twice and I checked speed/RPM and it was 30mph at 2100 RPM. I'm pretty sure it was in third gear after two shifts even though I still had the shifter in low gearr.
Any suggestions? And thanks for the help.

dieselclacker · 04-15-2013, 05:29 PM

wk2,

Third gear in your GM transmission is the direct or high gear, shift it up one position on the indicator to Drive position, and see if it shifts one time, and then up to the O Drive position to see if it shifts again. Some times a lockup type torque converter can be mistaken for an additional transmission shift.

monkey · 04-15-2013, 05:38 PM

Our 95 P32 only has 2nd as the lowest on the gear shift. You cannot 'force' it into first gear. It does shift down to first on the very steep hill up to our house.

wk2 · 04-16-2013, 09:06 AM

Let me ask the question differently. My shift quadrant has 4 forward positions: 1, 2, D, and OD. Starting from a dead sop, with the shift lever in the 1 position, the transmission upshifts twice with the speed/RPM then being 30/2100.
I thought it should stay in first gear if the shiftere is in the 1 position. Can anyone confirm this.

max49 · 04-16-2013, 10:00 AM

Mine is an '04 P-32. I also have 1, 2 Drive and Overdrive.
If I lock it in first gear, it stays in first up to 5000 RPM, maybe even 5200 RPM if it was being forced down by gravity, otherwise the engine shuts the fuel off until it get down to 5000 Rpm. I've never had it shift to 2nd gear if I had it pulled down in first. Maybe your transmission is different.
I would not like my tranny upshifting by itself. Out here in the Rockies , I often need first gear and still some braking to hold it back going down some mountains.

monkey · 04-16-2013, 05:38 PM

Since nobody has asked yet,,, what transmission do you have ?

dieselclacker · 04-16-2013, 06:45 PM

wk2,

30mph @ 3100 RPM sure sounds like second gear. 3100 RPM in third (direct) gear would be a greater speed than 30mph.

If your transmission is the older GM Turbo Hydro, you cannot lock it into First gear with the shifter, nor can you downshift it into First above a certain speed. GM built this feature in to protect the engine from excessive RPM's.

wk2 · 04-17-2013, 06:31 AM

Quote:

Originally Posted by monkey

Since nobody has asked yet,,, what transmission do you have ?

4 speed GM but I don't know the model number.

wk2 · 04-17-2013, 06:35 AM

Quote:

Originally Posted by max49

Mine is an '04 P-32. I also have 1, 2 Drive and Overdrive.
If I lock it in first gear, it stays in first up to 5000 RPM, maybe even 5200 RPM if it was being forced down by gravity, otherwise the engine shuts the fuel off until it get down to 5000 Rpm. I've never had it shift to 2nd gear if I had it pulled down in first. Maybe your transmission is different.
I would not like my tranny upshifting by itself. Out here in the Rockies , I often need first gear and still some braking to hold it back going down some mountains.

This is the way I think my transmission should work (stay in first gear under 20mph when shifted to "1"). Does anyone know if this is an "adjustment" that can be made?

max49 · 04-17-2013, 11:18 AM

Quote:

Originally Posted by wk2

4 speed GM but I don't know the model number.

I believe Ed or Driver could tell you what transmission you have if you give them your VIN.

Mine's a 4LP85 or something like that, I forget exactly but I should know that.

EngineerMike · 04-17-2013, 11:31 AM

I'm guessing these are 4L80E transmissions.
Had one in a P30. mine went nuts much like the OP describes. I think the brain gets a bad peyote button or something. Its rare but happened to me twice.
Disconnect the chassis battery & make sure the house batt's are not sending 12V to the chassis to keep voltage on the engine/trans computer. Then reattach chassis batteries & drive trouble free (reboots the computer). That worked for me the first time. Second time I took it to a trans service joint, shut it down & had it serviced; they couldn't find anything wrong including in a test drive prior to opening the pan (I drove 5 miles there in 2nd gear, couldn't shift up or down). I had them change the 1-2 & 2-3 shift solenoids as long as they had the pan off anyway, cost me another $75 iirc for parts and less than 1/2 hr labor.
Never had trouble after that.