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Code 81 and not shifting out of first

I drove it around the grapes and now it has code 21, I did check the TPS so would 21 come from checking that? Im going to go tear up the road and see if 85 comes back.

DTC 21 - Accelerator Pedal Position 1 Circuit High
 
I just took it for a little drive and no codes, it does shift hard from 1-2. When I checked the TPS I had .48v at idle and 4.99 wide open. This truck doesnt have a tachometer but it does sound like the rpms are high when it shifts in any gear. 1-2 is the only harsh shift. If you really get on it your teeth will get knocked loose. If you go real easy on the throttle about the time is shifts its not to bad but still a hard shift.
 
I just took it for a little drive and no codes, it does shift hard from 1-2. When I checked the TPS I had .48v at idle and 4.99 wide open. This truck doesnt have a tachometer but it does sound like the rpms are high when it shifts in any gear. 1-2 is the only harsh shift. If you really get on it your teeth will get knocked loose. If you go real easy on the throttle about the time is shifts its not to bad but still a hard shift.
Click to expand...

Sounds like it wants to shift a bit late.
Try adjusting the TPS to .50 and give that a try. Might work for you.
<<<<<<<<<<<<<I am getting rusty at this>>>>>>>>

I won't be surprised to see it shift a bit softer and smoother through first gear.
Shifting harder or softer for that matter will not necessarily trigger a DTC 21 or 22.
It's all about touch and go. a little bit, a hair,
 
GenBiltstein said:
Sounds like it wants to shift a bit late.
Try adjusting the TPS to .50 and give that a try. Might work for you.
<<<<<<<<<<<<<I am getting rusty at this>>>>>>>>

I won't be surprised to see it shift a bit softer and smoother through first gear.
Shifting harder or softer for that matter will not necessarily trigger a DTC 21 or 22.
It's all about touch and go. a little bit, a hair,
Click to expand...

How important is this .5v? I had a hard time playing with it. It doesnt take much movement to change it alot. I had it at .57 and drove it. 1-2 was still hard and it seemed like it made 2-3 harder. Still no trouble codes.
 
-------touchy------------.

Why it is shifting hard in 1-2 I don't know. If 2-3 is shifting harder because she is was adjusted then bring her back to .47. She might shift a bit softer. That is your end result your looking for.

It takes patience and a bit of time to find the right shift point.
If you can't

Clean the heck out of grounding. Engine/trans grounding. Easy way to do it is to check with a multimeter. Terminal ground at block .5 ohms. Battery post to terminal check .5... Positive post to terminal .5 ohms.
Negative terminal to chassis ground. .5---.7

After ground checks.

Passthrough connector. Squeaky clean pins.
 
I set it to .5 and it did shift better once. Im going to take it for a spin again tomorrow and see what it does cold. If that doesnt help Ill try .47. I was going to check the grounds today and forgot about it.
 
GenBiltstein said:
Clean the heck out of grounding. Engine/trans grounding. Easy way to do it is to check with a multimeter. Terminal ground at block .5 ohms. Battery post to terminal check .5... Positive post to terminal .5 ohms.
Negative terminal to chassis ground. .5---.7

After ground checks.

Passthrough connector. Squeaky clean pins.
Click to expand...

Adjusting the TPS doesnt seem to help any.

I checked the ground, from the transmission pan to the crossover pipe it showed 1.1. from the transmission pan to the neg battery terminal I had .7
 
When I drove the truck last I started in 1 and shifted manualy and its fine like that. Something is telling it to shift late.
 
That would be engine load. Allow me to explain. There are basically two signals going into the computer. The Engine RPM signal and the throttle position signal. I believe you addressed the throttle position sensor. Lets address the RPM signal. There should be a two lead wire harness coming from the from of the crank shaft on the driver's side. One goes to a ground and commonly shares a ground with the TPS. With the Military HUMMWV it does. With your model it might. Disconnect the leads and check for ground and chassis ground. If you are getting a chassis ground good. If not I would be curious to know if it shares the same ground as the TPS ground. Check it with the TPS ground.
Check the RPM sensor with the engine running and the Digital multimeter set on AC. Yes AC voltage. The signal is pulsed. DC will not register. The higher the rpms then the greater the voltage. The sensor is commonly referred to ESS. Engine speed sensor. If they get hot the resistance can increase and or go Kaputt.
Remember that magnetism plus motion produce current. This is the basic principle of these types of sensors.
The ABS sensors work exactly in the same fashion. It kills me that Stalerships charge an arm and a leg for these sensors. Nothing but a coil a diode and magnet. To the tune of 160.00. They are so small they will fit up a hampster's @ss.
If the connection goes "resisted" then voltage drop occurs. If voltage drop occurs then in this case harder shifting can happen. Think about it a bit. It will hit you like a brick.
A bad ground at the block, Battery ground, Battery to chassis ground, Ground anywhere inhibiting the free flow of electricity.
A computer takes the voltage from the rpm, takes the resisted voltage from the TPS and shifts accordingly.
If you are still shifting late then Ohm the resisted pin and on the TPs and make a slight adjustment to the TPS and note the difference on shifting.
Wear can happen within the TPS as well and can be checked with a multimeter. Ohm it slowly. A graduated ohm reading can be seen. one major shift can be seen within the TPS. This is for downshifting for passing gear.
Any difference noted beside that means a new TPS. There is a dual wiper inside. Miniature copper scrapers if you will. They run on copper tracks. You can actually take it apart and check it out. Even save the cost of a new one.
This stuff can be as easy as you want it to be.
 
Changing the ESS did nothing. I put the TPS all the way down to .25v and it shifts at a good rpm now but 1-2 is still a harsh shift. It has no trouble codes.
 
The issue with that is this. Suppose you have a delayed shift. Are you going to rebuild the transmission?
There are computer programs that emulate the Tech2. If I was there to help you diagnose that tranny it might be a different story.
Check out dieselplace 4L80-E transmissions. I put a ton of information on that site. Study what you have in your hands. The transmission is not that hard to grasp believe it or not.
RPM sensor to Transmission sensor = mechanical coupling
Manual selected gear has a transmission range pressure switch. This switch tells the computer what gear you are in. An expected gear output is resulted. No result = ratio error. Default second gear.
Vehicle speed sensor Location is at the transfer if 4X4. If 2X2 it might be at the transmission.
Transmission fluid temperature sensor. There is a chart telling you if is is skewed. (bad)
If you get a scanner you need to know how the transmission works. Easy enough if you wrap your mind on it.
 
Ive learned alot on how the transmission works, Id like to get to know it inside and out since they are supposed to be good transmissions and all the transmission shops around here are conartists.

I ordered the scan tool program last night, I have 3 obd1 GMs that all use the same aldl plug so I figured its worth the money.

We had nasty cold weather and rain the past few days and today I put a new exhaust on the jimmy so I havent had time for the truck. The truck Is my next project.

What would cause the hard shift, would it be high fluid pressure? And does having the TPS set at .2V to make it shift at the right rpm mean something is wrong?
 
I'd say more power to you. Knowledge is power.
As long as the scanner is reciprocal. Meaning you can shift with the scanner. Actuate EGR systems and the like. You will do good.
Let me know what you find out. I would be curious what your TPS is reading.
 
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