Newly rebuilt 4l80e (700 miles) now won’t shift into 3rd gear

[txaggie]

Howdy all,

Our dad gum suburban build is killing me. We had our 4l80e rebuilt by an old school reputable builder and now all of a sudden it shifts great in and 1 and 2 gears and then won’t shift into 3rd.
I can manually shift through all the gears and when I get to gear 3, no change in rpm (even though it shows 3rd) and then it shifts fine into 4th and lockup.

We are running a Holley sniper controller for it.

 

[Chevy 88]

Disconnect your kickdown linkage and see how it does. Will this get it into 3rd when coasting at 30 mph? If not, try moving the shifter to N while driving at 30, and let off the gas. Then does it go into 3rd?

 

[NickTransmissions]

Disconnect your kickdown linkage and see how it does. Will this get it into 3rd when coasting at 30 mph? If not, try moving the shifter to N while driving at 30, and let off the gas. Then does it go into 3rd?

There is no "kick down" linkage or cable for the electronically controlled transmissions as all shifting is comp-controlled.

We had our 4l80e rebuilt by an old school reputable builder and now all of a sudden it shifts great in and 1 and 2 gears and then won’t shift into 3rd.

Have you contacted the builder to report the symptoms? If so, what did he say?

Any problems in reverse?

 

[Ricko1966]

Disconnect your kickdown linkage and see how it does. Will this get it into 3rd when coasting at 30 mph? If not, try moving the shifter to N while driving at 30, and let off the gas. Then does it go into 3rd?

They don't have kickdown linkage

 

[txaggie]

There is no "kick down" linkage or cable for the electronically controlled transmissions as all shifting is comp-controlled.


Have you contacted the builder to report the symptoms? If so, what did he say?

Any problems in reverse?

Reverse is perfect. It’s easy to put new solenoids in these and my builder is out of town. I’ll just try that and see what happens?

 

[NickTransmissions]

Reverse is perfect. It’s easy to put new solenoids in these and my builder is out of town. I’ll just try that and see what happens?

Test them with a DVOM first to see if any are bad. Look to see if they are new. If not, you can replace the solenoids and seek reimbursement from the trans builder or have him replace the solenoids.

 

[Ricko1966]

Reverse is perfect. It’s easy to put new solenoids in these and my builder is out of town. I’ll just try that and see what happens?

They are easy to test without dropping the pan.

 

[txaggie]

Test them with a DVOM first to see if any are bad. Look to see if they are new. If not, you can replace the solenoids and seek reimbursement from the trans builder or have him replace the solenoids.

Got it all hooked up and it worked awesome for 30-40 minutes. After that, I now have random controller issues where the transmission only wants to go in reverse or 1st gear only. After some manually cycling through gears, it starts working again (what the heck)?

Wonder if this manifold switch could be bad out of the gm package?

 

[NickTransmissions]

Got it all hooked up and it worked awesome for 30-40 minutes. After that, I now have random controller issues where the transmission only wants to go in reverse or 1st gear only. After some manually cycling through gears, it starts working again (what the heck)?

Wonder if this manifold switch could be bad out of the gm package?

Are the speed sensors new? If not, id replace the rear speed sensor with the front one and visa versa to see if anything changes. Also check wiring to each sensor for damage, etc.

 

[txaggie]

Are the speed sensors new? If not, id replace the rear speed sensor with the front one and visa versa to see if anything changes. Also check wiring to each sensor for damage, etc.

New sensors there. I think I found the culprit, the main harness wasn’t fully seated. Drove it after and it was strong. We will see tomorrow to verify!

 

[txaggie]

Are the speed sensors new? If not, id replace the rear speed sensor with the front one and visa versa to see if anything changes. Also check wiring to each sensor for damage, etc.

Looks like the problem is back today. After driving and getting up to 200 degrees in the trans, all of a sudden the shift indicator shows (-1 reverse) when I’m in 4th gear. Next, it only stay in first gear or can go in reverse. If I turn the truck off and let it cool a sec, back to normal.

Weird thing today was that I had the internal temperature reading display to like -40 degrees and then read as an “error” and then corrected to plus or minus 10-15 degrees as my manual gauge (180).

Nick, being that Holley doesn’t have any codes it stores, where the heck should I start? Could a new harness be shorting out? Could one of my solenoids be shorting out?

Other than warm temps in the fluid 200 plus, this thing is shifting hard and well.

 

[NickTransmissions]

Looks like the problem is back today. After driving and getting up to 200 degrees in the trans, all of a sudden the shift indicator shows (-1 reverse) when I’m in 4th gear. Next, it only stay in first gear or can go in reverse. If I turn the truck off and let it cool a sec, back to normal.

Weird thing today was that I had the internal temperature reading display to like -40 degrees and then read as an “error” and then corrected to plus or minus 10-15 degrees as my manual gauge (180).

Nick, being that Holley doesn’t have any codes it stores, where the heck should I start? Could a new harness be shorting out? Could one of my solenoids be shorting out?

Other than warm temps in the fluid 200 plus, this thing is shifting hard and well.

Sounds like a short somewhere or a malfunctioning controller. Whenever factory PCMs detect anomalies with transmission-related sensors, switches or other electrical components, the PCM freezes all adapts, maxes out the line pressure and sometimes will put the trans into limp mode. For the 4L80E, that means 2nd gear only when in Drive and Drive3. Could be the pressure switch manifold assembly - it works with concert with the manual lever position sensor to communicate range position at all times to the PCM...The pressure switch manifold takes over once the vehicle is running while the MLPS communicates pre-ignition park/neutral confirmation or denial.

 

[txaggie]

Sounds like a short somewhere or a malfunctioning controller. Whenever factory PCMs detect anomalies with transmission-related sensors, switches or other electrical components, the PCM freezes all adapts, maxes out the line pressure and sometimes will put the trans into limp mode. For the 4L80E, that means 2nd gear only when in Drive and Drive3. Could be the pressure switch manifold assembly - it works with concert with the manual lever position sensor to communicate range position at all times to the PCM...The pressure switch manifold takes over once the vehicle is running while the MLPS communicates pre-ignition park/neutral confirmation or denial.

We put a new gm brand pressure switch manifold yesterday along with both 1-2 and 2-3 solenoids new. Pan looked clean, no clutch material.

Next it shifted awesome and felt good and then at high temps the wired controller shift indicator issue surfaced. We eliminated the manual level switch sensor at the start of the build; Holley controller doesn’t have connections for it anyway.

With the continued shortage, I may try to install a new harness tomorrow to see if that fixes it.

 

[NickTransmissions]

We put a new gm brand pressure switch manifold yesterday along with both 1-2 and 2-3 solenoids new. Pan looked clean, no clutch material.

Next it shifted awesome and felt good and then at high temps the wired controller shift indicator issue surfaced. We eliminated the manual level switch sensor at the start of the build; Holley controller doesn’t have connections for it anyway.

With the continued shortage, I may try to install a new harness tomorrow to see if that fixes it.

Continuity test the harness via the multi-pin connector and see if you get any anomalous readings. Could be the transmission wiring harness or could be something else. The harness should have been replaced during the rebuild - if it was not, that's a miss on the part of the builder. If it was replaced and he used either Delphi new OEM or Rostra harness then it's not likely to be the wiring harness causing the problem. But test anyway prior to replacement so you'll know for sure.

 

[txaggie]

Continuity test the harness via the multi-pin connector and see if you get any anomalous readings. Could be the transmission wiring harness or could be something else. The harness should have been replaced during the rebuild - if it was not, that's a miss on the part of the builder. If it was replaced and he used either Delphi new OEM or Rostra harness then it's not likely to be the wiring harness causing the problem. But test anyway prior to replacement so you'll know for sure.

Weirdly enough no continuity difference with the old harness. Put a new rostra in today and the temps are lower than they’ve ever been before 150-170 (and it’s currently 98 here). Drives wonderful, shifts hard. I guess the harness was it.

The tale tell sign to me was the abnormal line temp yesterday; 45 degrees, then 140, then “error.”