My wife'* '96 Bonneville has an intermittent transmission problem that has been getting progressively worse. Occasionally it would not move when put into gear. If I moved the shifter back to Park and then back into gear it would "catch". Now it almost will not catch at all. It caught for me today but would not catch for the past few days when I tried.

The odd thing is that the car will not roll even when I put the shifter into neutral (our driveway is on an incline). Also, when I put it into Drive or Reverse, the engine revs slow down just like it normally would, but the car doesn't move, and when I press the gas pedal the engine does not rev high like it does in park. It almost seems as though the transmission goes into gear and the engine is loaded but some mechanism is not allowing the transmission to unlock so the car can move. BTW, there is plenty of fluid in the transmission.

I'd like to be armed with a little more knowledge before I take it to the shop and they tell me that the tranny is shot and needs a $2000 rebuild. i.e., Is there a solenoid that is supposed to unlock when the tranny is shifted into gear ? Worn bands ?

Thanks, Hugh.

Im not really Exp with trannys, but could it be the Transmission Shift Linkage? Torque Converter?

How was it shifting when you were able to get it to "catch"?

locked diff?

se sse or ssei?

Today it caught and I drove it around the block and it shifts fine. I put it back in the driveway, shut the engine off, restarted it and then it would not catch. We're afraid to drive it anywhere in this state for fear of not being able to get home


It'* an SE.
What would cause the differential to lock and how is that fixed ?

a locked diff might occur if the pin inside of it broke.
this is a common problem in the 4t60-e tranny, in fact it happened to mine and broke the casing around it. usually happens because of excessive one-wheel-peels (like if you get stuck alot, common here in Canada(eskimo country))
other than that i would expect a sticky accumulator piston
either way its probably a good idea to let a qualified tranny shop look at a little closer

Hmmm...
If the pin inside the diff was broke would it still work sometimes ? With the intermittent symptoms I'm having (the tranny works sometimes but more often not), I would expect that it isn't something absolute like a broken part (i.e., if a pin was broke then it would not work at all anymore).

My daughter had about the same problem on her 91 grand prix...slipped in first gear when starting from a stop. Same thing...put it in park, start again - it worked fine. A mechanic I talked to said it was possibly a sticking solenoid, and suggested trying some Seafoam Trans Tune to see if that would free it up. I was skeptical and not a fan of tranny additives, but at $5.00 I thought it was worth a shot. It'* been working fine for about a month now. Might be worth a shot.

It almost sounds like it is something electrical. It doesn't make sense that the rpms wouldn't increase when you have it in gear. I mean, just think. When you do a burn out, you put the e-brake on and rev the car in gear. The rpms increase, but you don't move for a little bit. Same concept. The engine should rev up regardless of what the tranny is doing.

it could also be that the shifter cable has become stretched over the years and therefore not selecting the correct gear, and or being stuck inbetween 2 gears

This would be an easy one to test. Get a second person, put them in the drivers seat holding the brake. In the meantime, get under the hood and shift the linkage by hand from gear to gear. If it works when you do that, it is a cable issue. If it still doesn't, it'* internal to the tranny. This would be a cheap first shot, maybe avoid a trip to the tranny shop.