Speed sensor 8L90

[pedrofenix]

Hi. I know it?s a long shot but I?m currently having a Trouble with the speed sensor ( code: p077c output shaft speed sensor circuit low) on my 2016 Camaro 6.2. 8A So, I have changed the speed sensor, checked for wires and added 2 more ground to it. But the problem doesn?t seem to wanna go away. Every morning or after letting the car sit for a while it drives/works just fine for about 10min after that the speed sensor is flying all over the place and consequently going into limp mode.

So, I used the scanner and was monitoring the speed on it. After a while vehicle speed SAE and Driven wheel speed are not reading correctly sometimes they show 0 or just not read correctly. But the Undriven wheel speed shows the speed correctly. So. I was wondering if there?s a away within the Editor to make the main speed display the undriven wheel or to make the others show up the value from it.

Or if anyone has installed an aftermarket VSS to the wheel or shaft and connect to the tcm output cables and can share how it work.

I appreciate all the help I can get. Thank you.

[Estep40511]

Hi. I know it?s a long shot but I?m currently having a Trouble with the speed sensor ( code: p077c output shaft speed sensor circuit low) on my 2016 Camaro 6.2. 8A So, I have changed the speed sensor, checked for wires and added 2 more ground to it. But the problem doesn?t seem to wanna go away. Every morning or after letting the car sit for a while it drives/works just fine for about 10min after that the speed sensor is flying all over the place and consequently going into limp mode.

So, I used the scanner and was monitoring the speed on it. After a while vehicle speed SAE and Driven wheel speed are not reading correctly sometimes they show 0 or just not read correctly. But the Undriven wheel speed shows the speed correctly. So. I was wondering if there?s a away within the Editor to make the main speed display the undriven wheel or to make the others show up the value from it.

Or if anyone has installed an aftermarket VSS to the wheel or shaft and connect to the tcm output cables and can share how it work.

I appreciate all the help I can get. Thank you.

Looks like it can only be one of three things. You have a short to ground on the circuit. An open in the circuit. Or a bad TCM. The 8L90 has to have this input for Gear selection. Hope this helps. if you need help on which circuit to check between the sensor and TCM, just let me know and Ill get the diagram for ya.

[Estep40511]

Actually, I have seen the internal trans wiring harness have high resistance and cause this too. and the Passage sleeve in the trans, where the harness connects to the trans.

[pedrofenix]

I would really appreciate if you could point me in the right direction. Thank you!!!

[pedrofenix]

I changed the wiring harness/speed sensor. But I think you?re talking about the other wiring that has the temperature sensor? I was even thinking if it was the temperature sensor that would be causing this problem. Because the problem starts to happen when the car gets warm. Not sure what im talking about tho..

[pedrofenix]

I was able to change into the transmission tabs on hptuner the VSS/OSS Location? as ?no sensor?. So, the Vehicle Speed SAE is about the same as Undriven wheel (Abs sensors). And, set the P077C as no error ( so it does not go into limp mode).
However I?m getting some bad changes from 1-2. Sometimes it even goes right back to 1. And, it feels like the torque converter is always engaged but anything past 3 is pretty smooth. I was wondering if were able to change the parameters on the converter plus speed change point it would be smoother.

[Estep40511]

I was able to change into the transmission tabs on hptuner the VSS/OSS Location? as ?no sensor?. So, the Vehicle Speed SAE is about the same as Undriven wheel (Abs sensors). And, set the P077C as no error ( so it does not go into limp mode).
However I?m getting some bad changes from 1-2. Sometimes it even goes right back to 1. And, it feels like the torque converter is always engaged but anything past 3 is pretty smooth. I was wondering if were able to change the parameters on the converter plus speed change point it would be smoother.

what is your temp reading? is it steady or bouncing around everywhere? You may have more than one issue. the 8L90 needs the speed sensor input to determine gear selection. I would start by checking the pins on the transmission side of the harness. sometimes youll have one that backs out or has some corrosion on it. And yes the harness with the temp sensor has a connector that goes up to the speed sensor harness, under the valve body.

[cadillactech]

Don't overlook a reluctor wheel issue, while usually they set a performance based DTC, if the reluctor wheel that is machined into the output shaft machined incorrectly or a failed bearing supporting it is causing it to move away from the speed sensor then you can have issues.

Have you put a scope on the signal output to see what it is actually doing while driving?

[pedrofenix]

Temp doesnt hit more than 175F. Temp is stable. Tacho is stable. Only thing that bounces around is speedometer. Im having problems with the Output (code: p077c output shaft speed sensor circuit low).

I bought the car like that the transmission was bad. So, I toke it to a shop they rebuilt the transmission. It drove fine for 2 days. In the 3 day when I was on my way to work I saw the speedo bouncing and it went into limp mode. But, everytime if I unplug the battery or let it sit for a while. It works fine for a couple of minutes (Looking at the Scanner it gives the correct speed for output) but out of nowhere it starts to bounce around. I will upload the file.

And, Yes i did try to get the car back to the mechanic! But, when it happened we spoke in the phone he said it was a wiring problem or the sensor. And, i tried to get the car back to him cause of warranty but he would not pick up my calls or reply back. And, his shop is about 2h from my home. So, im just not gonna drive there if hes not even picking up my calls and the other day I called there and someone got the call and I could hear him saying to say he was not there. Found the shop at google saw the reviews saying they were good...

[pedrofenix]

It is 10min long Idk how to trim it but I started driving the car at 5:59 and the speedo starts acting up at 7:34

[pedrofenix]

So, As you can see on this file i was able to set the car driven/undriven both as the abs. But, if you look at Trans output shaft rpm. The rpm is getting stuck. Is is more reasons to believe it is a wiring problem or the reluctor? It only happens when the car is warm.

[brainofjjj]

Has there been any progress here?

I remoed my tcase from my 8L90 to make it 2wd with a fixed yoke from a Camaro and now i have no speed sensor reading. I read there are sensors in the 8L90, how could there not be, but my truck is now in limp mode.

[Estep40511]

There are sensors in the trans, but your TCM still thinks you have a 4WD not a 2WD, and thinks the transfer case is in neutral, so TCM defaults to limp mode. Id try deleting that DTC and/or get the OS for a 2wd and try writing that. That should fix it for ya.

[Texxmark]

Has there been any progress here?

I remoed my tcase from my 8L90 to make it 2wd with a fixed yoke from a Camaro and now i have no speed sensor reading. I read there are sensors in the 8L90, how could there not be, but my truck is now in limp mode.

I’m having same issue. Any luck on this

[kbkgo]

So, As you can see on this file i was able to set the car driven/undriven both as the abs. But, if you look at Trans output shaft rpm. The rpm is getting stuck. Is is more reasons to believe it is a wiring problem or the reluctor? It only happens when the car is warm.

I have same issue from 28 Feb 2023. I replace input/intermediate/output speed sensor twice so far today. I replaced the passage sleeve connector(20 pin) and oil temp. sensor harness also. But no lucky.
I can see output/intermediate speed signal jumping at vehicle parking situations.

Today, one wire installed to jumping from transmission passage sleeve connector to TCM connecter directly to avoid any speed signal distortion. But, no lucky. Same code raised up P077C.

Do you solve this problem?