[pedrofenix]

I recently got my transmission 8L90 rebuilt the car drove just fine for 2 days. Saturday morning I was heading to work and I noticed a hard shift from 1-2. Then, when I looked at the speedometer it was oscillating. After 5 minutes car went into safe mode. I got a few codes from it P0700, P0158, P077C, P16FB.

Before getting the transmission rebuilt the speedometer was oscillating already but when I picked it up in the shop everything was working until 2 days later. Maybe a bad tcm? Wires? The relearn process didn’t go well?

I just thought it was weird because it worked just fine for 2 days and next day I turn it on and it was like that.

I’ve looked everywhere and couldn’t find much on these codes. I appreciate if anyone knows anything about it or had this problem! Thank you.

[SSgtSS1LE]

References from 2017 Camaro 8L90 Automatic Transmission, but should be the same for 2016 Camaro.

P0700 Transmission Control Module Requested MIL Illumination

P0158 HO2S Circuit High Voltage Bank 2 Sensor 2
1. High Resistance, Open, or Short to Voltage
2. Wire Colors - White/Brown, Violet/Green, Yellow/Blue

P077C Output Speed Sensor Circuit Low Voltage - Short to Ground or Open/High Resistance
1. Wire Colors - Yellow/Green, Gray/Blue

P16FB Control Module Speed Signal Analog to Digital Converter Performance

Check for damaged wire harness on passenger side underneath.

[pedrofenix]

I’ve checked for damaged wires and the wires looks good. So, I changed the speed sensor inside the transmission but still no lucky. Same code.

So what I found that’s very weird is that if I let the car sit for 2 days or remove the battery and plug it back in the next day the speedometer works fine for 10 minutes. Then, it starts to act up again. So, I’m not sure if there’s something related but it looks like when the car is warm thats when the problem is happening. Something that would affect the voltage? I appreciate all the input I can get thanks. I dropped off the car at a dealer close by and they said they wouldn’t work on it because it’s a rebuilt tittle. :3

[SSDan]

This is a long shot idea but easy to do and that is to add another ground cable. The 2016 model in particular has issues with bouncing tachs, slow crank on hot start and other odd electrical gremlins. Adding another ground cable has helped more than one person with this stuff. Apparently the 2016 model has an inadequate/ineffective factory ground between the drivetrain and the body. Here is a link to a thread to show you how to add the ground cable:

https://www.camaro6.com/forums/showthread.php?t=586153

I don't know if this will help with the bouncing speedo but worth a shot. Chasing down and fixing these odd ball types of problems can be maddening! Good luck.

[pedrofenix]

Just did it. I really thought it would work lol. I added one in front and another in the back just like you did and also changed my connectors. But unfortunately no lucky, same thing. Turned it on and went for a test drive. Drove fine but after a few minutes same thing.

I had the hptuners connected to it and was looking at the sensors. And, all of a sudden veicule speed (sae) and driven wheel went all over the place. Undriven wheel speed was the only one that kept sane lol. Thank for the help tho…

I’m honestly thinking on installing a universal wheel speed sensor and connecting to the tcm. The car has been like this for 2 months already.

[SSDan]

Bummer! The mystery continues. At least with the improved grounds you should avoid any future slow crank on a hot start issues that many 2016 SS cars experience. I’m sorry I have no more long shot ideas for you.

I wish you the best as you continue the troubleshooting. Keep us posted.

[pedrofenix]

It’s indeed a mystery. I’m thinking about getting new wires/tcm and see if that does the job.

Meanwhile, I know that’s not a permanent fix but what I did was to set under “Transmission” on HPTuners “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).

Only problem is that sometimes the car is only changing gears in high RPM. And, if I try to tap up I get a message shift denied. I know that’s something I also have to figure out in the transmission tab.

If anyone has any knowledge on how to change the parameters so I don’t get this message and get better shifting. I really appreciate it.

Thank you so much. I hope I can find the problem soon so if anyones ever get into this problem they will know what to look for.


Edit: forgot to mention also on the HPTuners at the Speedometer tab change “TOS Electrical interface” to “4” which is the non-driven.

[ctrlz]

Check to make sure your reluctor is not slipping.
As per this thread:
https://www.camaro6.com/forums/showt...php?p=11115174
Post #10 links to the TSB.