transmission won't shift out of second.

[Marty Lau]

Well folks here I am asking for thoughts which are always appreciated. My 4L80 transmission on my truck won't shift out of second gear. I get codes 73 pressure control circit, 74 transmission imput sensor curcit, and 81 2-3 shift soleniod circit. I changed out the sensors on the driver side of the transmisson and have ordered the solenoid. I also swapped back to OEM E-Prom no luck. Any other thoughts? Truck has 173,000 miles. Thanks as always for the help.

[cruzer]

I had a speed sensor go bad, after I replaced it, it still had the same symptoms, which was shifting hard 1st to 2nd and no D or OD. A Mr. Goodwrench mention sometimes you have to disconnect and reconnect the batteries to reboot the computer after sensor replacement. I did, and all is well. I don't know if this is your problem or not.

[Marty Lau]

Cruzer, Thanks I'll try the battery disconect, I didn't do that after changing sensors.

[ucdavis]

I too had a stuck-in-second episode that went away on a reboot.
I guess that old joke about if GM built cars the way Microsoft builds software isn't 100% a joke.

[ttpost]

is your speedometer working i had a similiar situtation and it was a bad vssb

[Marty Lau]

:rolleyes: Well after rebooting the truck it still won't shift past 2nd. :(
With the sensor change I dropped 2 codes. The truck is still showing code DTC 81 & 83. I'm waiting on the shift solenoid.
The speedometer is working fine.

[JohnC]

Solenoid codes can be caused by voltage problems in the solenoid circuit. Voltage problems can be caused by faulty contacts in the ignition switch. Check the voltage on the trans fuse immediately after turning on the key. Anything less than about 10 volts will set codes and put the trans into "limp" mode.

[ttpost]

once again i had the same problem and the same codes, and my speedometer worked,but my vssb wasnt sending a signal to the computer, it was only partially working.

from what i understand it is a rare thing to happen, which suprises me because it sits below the glove box so if anything was spilled in the glove box it would go into the vssb.

if your solenoids dont take care of it you may want to look it over, mine just had a little corrosion on one of the terminals, but it was fried good luck.

[patrick m.]

i think John c has the answer. 95 models are noted for ignition switch troubles.

[Marty Lau]

Okay so here is an update! :rolleyes:
I changed the two outside transmission sensors I have chaned a couple of solenoids and valves inside 1-2, 2-3, TCC, and Pressure, I have changed the ignition switch, check all fuses, and clean contections. THE local Transmission guy drove it and said he sure it's something electronic, it start off in second stays in second until you let off the accelorator it shift to 3rd. No signal some where. I'm going to try the VSSB and conections and the Accelorator pedal modual clean up. Any other thoughts...... HELP!
Thanks for all idea's.

[JohnC]

What codes now? You might want to drive with a Tech II hooked up and see what's going on. If it shifts into 3rd under any circumstances then it's not in "limp mode"

[ttpost]

that is different than mine, mine would start out in first, then under hard rpms would slam into second, but under no circumstance would it go into 3rd. alldata.com is the program chevy uses to diagnose the problems with their trucks. it cost 25.00 a year to sign up but it is well worth it.
it really helped me out and it makes a chiltons look like a comic book. they have great diagnostic procedures.

if you have a meter that will read hz you can see if your vssb is putting out a signal to the computer i believe it is the brown wire but you need to double check. good luck

[Marty Lau]

okay DTC 81, 82, 83. The accelrator pedal modual has one area that is not doing what is suppose to. Any one know the part # for the black modual that mounts on the pedal? I can't use the GMparts direct Alt. catalog on the home computer for some reason?

[MTTwister]

16gaSxS - Have you tried the "clean the Acc Pedal Module?" Drilling 2 holes, filling wiht electric contact cleaner, swrill and swrill and dump & drain.. It was in a thread back aways, I believe. Something to try in your spare time. :D
--- Edit - Oops - See that you had that on your platter in an earlier post. Hope your getting a handle on it, tho' .

[ 06-28-2004, 07:42 AM: Message edited by: MTTwister ]

[damork]

If you are getting inconsistent voltage to your transmission you might consider changing out your ignition switch or at least providing a relay between the switch and the transmission.

I added a relay a year ago (same kind as you power fog lamps with) and so far it works well. I believe there is a pink wire at pin E in my 95 that I tied the relay output to.

Also check your output speed sensor to ensure you don't have gunk built up on it. I could impact your shifting. I chased this one a long time before I found some Hummer's were having shift problems and this was causing it.

[Marty Lau]

TTPost;
Thanks for tha ALLData referal your right great service. Between Chiltons & ALLData trouble shooting we did about as much as we could with a multimeter. We pulled the Accelerator Pedal and cleaned the module as per some old posts here on the TDP Forum. On ALLData I found a TSB that showed changing actuator feed screen GM #8661709 that if the screen is torn it will shift to 2nd and stay there. It's like $5 list. Also have a Transmission Fluid Pressure switch GM # 24222077.
This has 5 pressure switches in one unit and it sends different signals over 3 wires depending on which switches are opened or closed by pressure.
This part cost me $28 at G&M a AC Delco warehouse that has a counter that will sell to any one. Dealer list is $42 GMParts Direct.com $32 with shipping. I been finding that their prices are bit better many times considering shipping than GMPartsDirect someitmes they are just a couple bucks more.
Damork; Thanks changed the ignition switch Thursday, didn't help. :confused:
So any way I will giving these a go so far.....still STUCK in 2nd. :rolleyes:

[Marty Lau]

Update on the stuck in 2nd......YAHOOOOOOOO! It is fixed. After changing and clean and check and thinking and trouble shooting tons of stuff, I got the truck in to the local Chevy Dealer (a good one) Their folks trouble shot it for 3 hours. Took it for a test drive and TAAADAAAA everything works, shifts great. The problem they don't know what fixed it! There was no power to the 1/2 solenod, they check every conection and the wiring harness and didn't find anything definate. I can't complain their regular shop rate is $66/hr they charged me $150 and they had 3 hours in it. I ran out of idea's and patience, I'm just glad I didn't run out of money.

[garre1tt]

16ga SXS,
Almost a year the date since you had your shifting problem I have developed the same.
DTC 81 and 83 and will not shift out of 2nd.
I am going to take it to the Chevy dealer to see if they can make it work for me to.
Do you have any advice before I do and did you have any other problems in the past year with the tranny?
I am using a B&M shift enhancer anyone have any problems with them?
Michael D.