4L80E Low and Reverse only

[gearlash]

2 WD 4L80E in a 69 Chevelle. won?t shift up from low. It has reverse. Drove the car to the body shop and it worked fine, a couple weeks later on the way home it would not shift. Old, abused trans, so,  rebuilt the transmission and it has the same problem as before. Will not display output speed sensor on scanner
With a digital voltmeter we can see a signal between pins 20 and 21 (output speed sensor pins) on the red connector at the ECM when manually rotating the tires. But it will not show any output speed on the scanner. 
It has about 1400 ohms resistance across those same two wires that go to the output speed sensor.
TIA for ideas.

[RDF1]

Confirm the connectors are firmly seated?
Are you sure its low gear and not 2nd gear?

Confirm power at Pin E at the transmission 20 pin connector

Do you have Trans fluid temperature reading and the Pressure Manifold switch readings?

[gearlash]

Connectors are seated and screw is tight.
Lot's of rpm's at a very low speed so we do believe it's low.
20 on the connector rings to the wire on the output speed sensor. The other wire is ground (low ref).
I now have fluid temp. Did not previously due to the fact that we only need to move the car a few ft to determine no out put speed signal.
By manifold switch readings's, do you mean solonoid states on/offf?
The pink wire at the trans connector has 12v and will light an 1157 bulb.

[blindsquirrel]

The pink wire at the trans connector has 12v and will light an 1157 bulb.

Yes great but is that 12v making it through the connector and into the internal harness?

[gearlash]

Can't be sure now. But, it does have a new internal harness and solonoids.
Once we discovered that there is no output shaft signal we started concentrating on that.
I don't believe it can shift without a speed signal.
It's my son's car and he lives several miles away. so may not get a chance to scan it again for a while.
Thanks!

[blindsquirrel]

It doesn't need electrical power to go park/reverse/neutral/low (actually second, which the 80E defaults to with no +12v; 60E defaults to third).

[RDF1]

Connectors are seated and screw is tight.
Lot's of rpm's at a very low speed so we do believe it's low.
20 on the connector rings to the wire on the output speed sensor. The other wire is ground (low ref).
I now have fluid temp. Did not previously due to the fact that we only need to move the car a few ft to determine no out put speed signal.
By manifold switch readings's, do you mean solonoid states on/offf?
The pink wire at the trans connector has 12v and will light an 1157 bulb.

Lots of rpms at low speed could mean your pushing on the converter when trans is defaulted into 2nd gear.

Pressure manifold switch reading means the trans is hydraulically pushing on the switch to tell PCM its got pressure on that switch so it can determine what gear its in.

[gearlash]

You're right about the rpm's. It has a really loose converter.
What would be the name of that channel. The term "manifold" does not exist in my channel list.
Thanks

[blindsquirrel]

Key on engine off, if you command solenoids on/off can you hear them click? That's the least invasive way to verify the power on the pink wire is making it all the way inside where it needs to go. No clicks = no power.

I know it gets old being told over and over to check a thing you're almost certain is OK, but it's really really common for that pink wire in the 20-way to get pushed back in the harness-side connector and not make good contact. And it seems like it's always only that one terminal for the pink wire that it happens to. Real common.

[gearlash]

Thank you. We will check it next time it's available to take another swing at it.

[RDF1]

You're right about the rpm's. It has a really loose converter.
What would be the name of that channel. The term "manifold" does not exist in my channel list.
Thanks

I dont see it either. i searched each term and not seeing anything at all.

In EFI its labeled Pressure Manifold Switch A B and C. You can watch each one go On/OFF to determine whats going on in the transmission pressure wise. Easy to determine crossleaks and such.

I agree with squirrel tho, Use your scanner special functions and command solenoids on/off and if you hear them that means the complete circuit from power to PCM controls are good.

Your speed signal one is a weird one tho.

Post your tune.

[gearlash]

How do I post my tune?

[blindsquirrel]

Click 'Go Advanced' below the quick reply box, then scroll down. There's a section for attachments.

[RDF1]

Was this a manual transmission PCM?

[RDF1]

Here is his tune

[blindsquirrel]

Was this a manual transmission PCM?

Doesn't look like it - trans & trans diag segments are both the same as other '02 2500/3500 files I have, but TIS is showing a different ID for transmission in the most recent release.

[RDF1]

Why are most the DTC's disabled?

[blindsquirrel]

Why are most the DTC's disabled?

"We don't need none of that emissions crap, turn 'em all off" ?

[OffroadH2]

Make sure your oss reluctor wheel is actually installed. Pull the sensor and you should be able to see it. The sensor will read with a scope/multimeter without it installed, but it?s actually picking up the pulses from the park gear which is right next to the sensor hole.

This one threw me for a loop one time. Got the trans rebuilt and not really sure what happened to it.

[RDF1]

Make sure your oss reluctor wheel is actually installed. Pull the sensor and you should be able to see it. The sensor will read with a scope/multimeter without it installed, but it?s actually picking up the pulses from the park gear which is right next to the sensor hole.

This one threw me for a loop one time. Got the trans rebuilt and not really sure what happened to it.

Good idea.
But every transmission ive worked on that didnt have the reluctor on the output drum was picking up the park pawl ring and giving half the speed of what it should normally be.