So I'm driving home from work this morning (night shift) and I get caught at a yellow light. Light turns green and I take off, then all of a sudden it felt like I ran over something or someone rear ended me. I look around and no one is in sight, so I figured I hit a pot hole in the street. Then I feel it again, but not as hard. By this time I'm at another red light and running things through my head at the same time. Only thing that came to mind was my transmission. So now I'm paying attention to the shifting as the light turns green. When the truck shifts into 2nd, it seems like it's slamming into gear. Going into 3rd isn't near as bad and OD is hardly noticable. I've never had a transmission go out on me so I'm wondering what happens when one does go bad. What are some possible problems that will make the tranny slam into gear and progressively get smoother all the way out? BTW, it is an automatic and I have 103k miles on it. Fluid and filter are almost 2 months old. No mods to tranny have been done. PLEASE HELP!!!!!

PM camaroRX for a positive answer.

So I'm driving home from work this morning (night shift) and I get caught at a yellow light. Light turns green and I take off, then all of a sudden it felt like I ran over something or someone rear ended me. I look around and no one is in sight, so I figured I hit a pot hole in the street. Then I feel it again, but not as hard. By this time I'm at another red light and running things through my head at the same time. Only thing that came to mind was my transmission. So now I'm paying attention to the shifting as the light turns green. When the truck shifts into 2nd, it seems like it's slamming into gear. Going into 3rd isn't near as bad and OD is hardly noticable. I've never had a transmission go out on me so I'm wondering what happens when one does go bad. What are some possible problems that will make the tranny slam into gear and progressively get smoother all the way out? BTW, it is an automatic and I have 103k miles on it. Fluid and filter are almost 2 months old. No mods to tranny have been done. PLEASE HELP!!!!!
Try cleaning your speed sensors on your trany.

Carey

I went thru the exact same thing one time last week, and I mean EXACTLY the same thing. After I shut the truck off and restarted, it hasn't happened since.

The general concensus I gathered here is the two speed sensors are at fault. They're relatively cheap and easy to replace.

Hadn't heard anyone mention cleaning them before.?.?

Can someone then point me in the direction of the speed sensors (location)? Don't have the REAL repair manuals, I only have the "vague" manual from my local parts store that tells me not to mess with tranny beyond fluid checks (some help that is)!

What you are describing is VERY similar to what happened to me last summer. While just cruising along, the tranny stopped pulling, or seemed to be slipping. I pulled over, put it in Park & checked the fluid level - OK . I pulled it down into drive & a huge WHAM occurred - it still didn't pull right but I was able to limp into a nearby parking lot. I called for a wrecker & had it towed to a local AAMCO shop. I might mention that I was 600 miles from home, on vacation.

Anyway, the tranny in my '95 K-3500 had to be rebuilt (about $ 2K with a 36 mo./ 36K mile warranty - it had made 185K miles prior to this failure) but the WHAM apparently tore up the Transfer Case also. It was full of metal, etc. The transfer case cost me another $ 1800. The AAMCO folks said that some of the electronic controls in the tranny tested out bad & had to be replaced. Perhaps, the malfunction of these controls was what was causing the WHAM, I can't say for sure. There was absolutely no prior warning before this occurance - no slipping, nothing. The only thing that I now see that was amiss was that the fluid temperature varied between 180 & 210 as I commuted back and forth to work. After the re-build job, the temp varies between 130 and 170 while I drive the same route to/from my workplace. There was obviously something causing that extra temperature, even though the tranny shifted normally and pulled normally. GM makes on hell of a transmission for these trucks, even tho there are shortcommings with the engine.

Don't take this lightly, would be my advise.

QM - I can't find camaroRX on the member list.

This is a link to the thread I posted last week regarding the same issue.
http://dieselplace.com/forum/showthread.php?t=26510

This is what I was told by one of the people here who had just replaced these sensors because of the same symptoms.
They are both on the driver's side. The input sensor is on the tranny just behind the bell housing and the output sensor is on the transfer case for our 4x4s. I replaced them at different times so until I looked them up for you I wasn't even sure they WERE the same part #. It only took me about 5 min to change them they are held down by a 10mm head bolt, just so you know what to climb under there with. Good luck!
And this is a picture of what they look like.
http://partimages.genpt.com/partimages/77531.jpg

The speed sensors are about $45 each, but I've found them as low as $25. they are the transmission input speed sensor, located driverside mid tranny, two wire connection. Vehicle speed sensor (VSS) is near the tailshaft on 2wd and on the rear of the T-case 4wd, also a two wire connection. If you pull them, and you have the OEM style with alot of exposed magnet, vs the newer plastic covered style, it wil have metal fragments all over it, just like any magnet would.
here's a link to pm 69camarox sorry, I wrote it wrong.
http://dieselplace.com/forum/private.php?do=newpm&u=11677

QM: So what is the purpose of the speed sensor? To remove metal flakes by magnetism and ?

No, it just picks up the passage of the tranny internals and signals it to the ecm. When the two signals don't equate the tranny gets a ratio error or other and doesn't shift.

How much fluid is going to ooze out when a guy pulls each of these for replacement/cleaning?

A drip or two. They're pretty high up on the body.

Just a thought, but what if the torque convertor is locking up as it shifts into 2nd gear?

Check for codes first. Short together the 2 top right terminals on the data link connector, turn on the ign then count the engine light blink codes. First code will be 12, repeated 3 times and then any other codes will be flashed the same way.

As an example:
*-**--- (code 12, will repeat 3 times) ********-*****--- (code 85, will repeat 3 times)

i think qm was refering you to me the first thing you need to do is check for codes there are some codes that will cause the trans to go to maximum line pressure eg. 73 force motor current this will cause the trans to act the way you describe. the reason it shifts softer in 3rd and 4th is the higher ratios you just don't feel it the same it is really just as much pressure just not as noticeable .

Doesn't the SES light come on if it throws a code(s)? If so, then I have no codes to check. Or are there codes that will not trigger the SES light?

Yes, codes can be stored regardless of whether or not the SES light came on. I got three last week when my tranny did this crap, and the SES light never came on.

Thanks Huisman, I'll check it out when I get home in the morning and give an update as to what I find.

Well I pulled 2 codes:

33 - EGR control pressure/Baro sensor circuit high (low vacuum) and,

85 - Undefined ratio error

Sounds like I have two different problems and need two different solutions. Anyone want to take a stab at these?

Not sure about the EGR code, but I know I got an 85 last week two.

Why not just pull the sensors, wipe them clean as mentioned earlier, and see what happens? Won't cost you a penny.

the 85 will give you maximum line pressure you will need a scanner to figure it out pm me and i will explain more

Code 85 sets when the ECM's calculations indicate an unexpected gear ratio and it doesn't include OD. default line pressure max. I'm looking over the manual and the sensors track the forward clutch and rear clutch speeds.

I appreciate all the help/advice that everyone has offered. Unfortunatly I will have to get to this at a later date since I threw my back out and I'm on all kinds of pain meds and muscle relaxer's right now. Getting under the truck won't be a problem, it's getting up off the ground. I'll let you all know what happens when I get to it.

Does anyone know about the code 33 - egr control pressure/baro sensor circuit high(low vac)?

Yes,
You have to read vac at idle on the rubber line to the egr ~5" hg, and the baro sensor ~20" hg.
Anything lower than 20" on the baro will throw the boost/egr cycle off.

Well, I removed the speed sensors and cleaned them off (they were not dirty). I also reset codes (brake and accel pedals in). Drove truck around and everything was working right. So I decided to drive it to work tonight and everything is A-OK....for now! Sounds like it might have had an electrical issue/spike and threw a code that stuck until I did a reset.

Mine did something similiar when I had a shorted wire leaving the PCM just outside the firewall. I replaced everything twice at four different shops before I found the shorted wire.