Passing gear won't engage!

I have a 1995 Buick LeSabre. The passing gear will never engage. Any suggestions as to what needs to be fixed in order for it to work properly? Any information greatly appreciated. Thanks in advance!

Has anybody had this problem?

I haven't had this problem in my Lesabre, but I had that problem in a truck I used to have. I had substituted an after market carb and did not hook up the transmission downshift linkage to the automatic transmission. So, if I stomped on it, it just kind of accelerated slowly. Someone told me it wasn't good for the transmission. I think he said it had something to do with the pressure plate in the transmission. In a 95 Lesabre, I would look for any codes first. There is a control box that is to work the transmission down shift, unlike the old manual linkages to the transmission. Maybe the problem is electrical. I don't think there is an adjustment for it. Had an Oldsmobile once that had a cable for the transmission down shift. It was adjustable, but the ones that are electronically controlled do not have an adjustment. Autozone will check the OBDII codes for free.

The problem with the 1995 Buick LaSabre is that it has an OBDII type diagnostic port but the 1995 LaSabre is an OBDI computer. When they tried to check for electronic codes, the code reader read that it could not establish a connection. What should I do to read the electronic codes?

Hmm...my book says that only some of the 94 models are OBD II compliant if they have a 16 pin data link connector. It says that all 95 models are OBD II compliant, so an OBD II compliant scan tool should work for a 95. If it is OBD I, most codes can be obtained with a jumper wire between two of the terminals in the data link connector. In another recent message on this board, I believe someone posted how to obtain the OBD I codes by grounding one of the terminals.

You can access OB1 & OB11 codes on the link below:

http://autorepair.about.com/cs/generalinfo/l/bl_dtcs_main.htm#1992
Diagnostic Trouble Codes

:grinyes:

I checked under the hood near the hood latch. There is a sticker there that says that the car is OBDI certified. If my 1995 LaSabre is OBDI but has a OBDII connector, how do I retrieve the electronic codes?

I have a 1995 Buick LeSabre. The passing gear will never engage. Any suggestions as to what needs to be fixed in order for it to work properly? Any information greatly appreciated. Thanks in advance!


I would check & change the Transmission Modulator Valve first!
It very likely its bad. And its a cheaper alternative to first start with.

The transmission needs the correct vaccum pressure on the line!
In order to shift correctly and smoothly.

The 4T60E transmissions have a Transmission Modulator Valve (vaccum)

The 4T65E transmissions have a Pressure Control Solenoid (electrical)

Check these before going off and buying cheap aftermarket solenoids!!!

How can I determine which transmission my car has?

By the way, the car shifts fine through all gears except that the passing gear never engages when wide open throttle when I floor it!

How can I determine which transmission my car has?

Its written on the bottom of your tranny oil pan.
95 has the 4t60e like my 93 I blelieve.
Look for a vaccum line that goes to the front driver side of the tranny.
See if there is a nice strong vaccum there, if not.
There is a problem. If there is a good vaccum, I would check the modulator next.

If the passing gear is not downshifting when you floor it. It could still also be the modulator I believe. Change it due to the cost of expensive diagnostics.

ITs a tranny that has over 200 little pieces in it. Could be solenoids, could be clogged passages, could be anything right now.

Also make sure the fluids are topped off at the correct level, and dont smell burnt from the dipstick.

When was the last time you changed trans fluid and filter?

Most of the time the Check / Service Engine Soon light will never come on for tranny problems....

My 2 cents...

I changed the tranny oil and filter about 2000 miles ago. The passing gear has never worked for me since I bought it two years ago.

Where is the modulator and how do I replace it?

Where is the modulator and how do I replace it?

The Modulator is to the front of the tranny on the drivers side.
You will see a small vaccum hose pluging into a round device (modulator)
Its bolted in by 1 bolt. Just unbolt and pull it out with the O-ring.
Replace it with the new one!!

Note: when replacing the new modulator, it must be adjusted!!
There is a small screw in the middle of the modulator where the vaccum hose conects to it.

Adjust that counter clockwise for quicker shifts, OR
Adjust it clockwise for firmer, longer shifts.

Figure out what you like best, and see if its downshifts on time.

Does the modulator have a maximum and minumum amount of adjustment? Does it work with vaccum only? No electrical connections?

The transmission modulator was replaced. It was busted and not functional. That did not fix the problem even though I had a little more throttle response. The passing gear now engages perfect once I installed a new throttle position sensor and idle contrl valve. Both the TPS and Idle control valve were stuck. The car now runs excellent!!!!!!!

You will be fooling with this forever. To determine whether this is an internal mechanical problem or a shift solenoid problem it must be scanned with a trans capable scanner to confirm solenoid operation especially when full throttle kick down is commanded, I assume a manual shift down to 3rd is ok even though it will not down shift automatically at 50 or so.

The car shifts perfect!!! The passing gear works perfect now!!!!! Yea!!!!!!!!!

The passing gear now engages perfect once I installed a new throttle position sensor and idle contrl valve. Both the TPS and Idle control valve were stuck. The car now runs excellent!!!!!!!
The car shifts perfect!!! The passing gear works perfect now!!!!! Yea!!!!!!!!!

It helps to keep the updates in a new post, rather than editing an old post.:grinyes: