4l80e P1870

[jacob_mckellar]

I have a 1996 c3500 dually with 5.7/4l80e I have code “p1870 transmission component slipping” which causes the trans to go into limp mode and I lose OD and tcc lockup I have replaced the valve body with all solenoids I have replaced input and output speed sensors and even torque converter with no change not sure where to go from here truck seems to drive fine until it throws the code although tcc slip speed is all over the place not sure what is okay as far as slip speed, also when it throws the code I can shut the truck off for 2-3 mins fire or back up and it drives fine until code comes back. I’m at my wits end with this thing any input is appreciated

 

[NickTransmissions]

Did you replace the wiring harness and update the TCC regulator valve. Transgo, Sonnax and Central valve bodies all have updated/improved valves to address TCC reg valve wear (which is common in the 80)?

 

[jacob_mckellar]

Did you replace the wiring harness and update the TCC regulator valve. Transgo, Sonnax and Central valve bodies all have updated/improved valves to address TCC reg valve wear (which is common in the 80)?

I replaced the entire valve body with an updated version with updated valves still no change

 

[NickTransmissions]

I replaced the entire valve body with an updated version with updated valves still no change

Wiring harness- did you replace that?

 

[jacob_mckellar]

No I haven’t replaced the internal wiring harness, I did visualize it and inspect it visually nothing seemed off, another thing to note is I also have an o2 sensor code everytime

Wiring harness- did you replace that?

 

[NickTransmissions]

No I haven’t replaced the internal wiring harness, I did visualize it and inspect it visually nothing seemed off, another thing to note is I also have an o2 sensor code every time

Replace the harness as they are known for shorting out and putting the trans into limp mode. They sometimes leak through the connectors or just malfunction. Visual inspections won't detect all problems - at the very least you need to probe it for continuity or voltage. When i rebuild any electro-mechanically controlled transmission, I always replace all of the electrical stuff (solenoids, pressure switches, wiring harnesses, MLPS, etc).

If the new harness doesn't resolve the issue, then check your vehicle's external wiring harness for continuity/power, if you haven't already. Also check vehicle/engine grounds....If those all check/test good, the problem is either inside the transmission's case (i.e. the ECM is detecting a gear ratio error somewhere based on it's data streams coming from the two speed sensors in concert with it's shift strategy table values based on what they should be in a given gear at a given speed) or your ECM itself is going bad.

 

[jacob_mckellar]

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[jacob_mckellar]

Replace the harness as they are known for shorting out and putting the trans into limp mode. They sometimes leak through the connectors or just malfunction. Visual inspections won't detect all problems - at the very least you need to probe it for continuity or voltage. When i rebuild any electro-mechanically controlled transmission, I always replace all of the electrical stuff (solenoids, pressure switches, wiring harnesses, MLPS, etc).

If the new harness doesn't resolve the issue, then check your vehicle's external wiring harness for continuity/power, if you haven't already. Also check vehicle/engine grounds....If those all check/test good, the problem is either inside the transmission's case (i.e. the ECM is detecting a gear ratio error somewhere based on it's data streams coming from the two speed sensors in concert with it's shift strategy table values based on what they should be in a given gear at a given speed) or your ECM itself is going bad.

Is this normal slip speed at lock up in OD

 

[NickTransmissions]

Is this normal slip speed at lock up in OD

Nope, not if that's the slip speed you're seeing when in 4th and TCC is applied. You've found out why P1870 keeps storing.

What's the slip speed when you're in third gear and TCC is applied?

 

[TW97]

I have a 1996 c3500 dually with 5.7/4l80e I have code “p1870 transmission component slipping” which causes the trans to go into limp mode and I lose OD and tcc lockup I have replaced the valve body with all solenoids I have replaced input and output speed sensors and even torque converter with no change not sure where to go from here truck seems to drive fine until it throws the code although tcc slip speed is all over the place not sure what is okay as far as slip speed, also when it throws the code I can shut the truck off for 2-3 mins fire or back up and it drives fine until code comes back. I’m at my wits end with this thing any input is appreciated

I have a 4l80e it was shifting fun. The wiring on the outside had bare spots from oil damage. I put heat shrek on them. Shifts good. But i think the torque converter is bad. I believe yours is internal wireless harness. Good luck