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Discussion Starter · #1 · (Edited)
I am super close to getting this car on the road after a long journey.

I have a few problems with "charging system" but that seems to be intermittent right now and not too worried about that.

What I am needing some feedback on before I decide to tow the car to the dealership for a real scan. I know others have come across this before so I am hoping I can find a fix on my own before going through the dealership route.

The remote will light up the reverse lights so I know they work. The dash will not show what gear the car is in nor will it light up the reverse lights. I need reverse lights so I can get a brake and lamp inspection complete to get the car on the road. I am hoping and assuming that if I figure out whats wrong with that, it will help with the other items. I get "service stabilitrak", "Service traction control", and "Parking assist off" along with the ((P)) on.

I have attached some photos. I do get error codes that the TCM lost communication U101 along with p0700 requestoing the mil light. I am sure the code p0602 is important but not sure that is related to the TCM and the errors on the dash.

Any suggestions that I can check on will be appreciated and I will gladly check on them as long as its related to the car problems.

Thanks!

ps..oh the car shifts in gear properly and theoretically drives fine. I say theoretically because I have only had it driven onto a trailer on and off for the exhaust work. Car has no plates and needs to be tuned so I can't risk driving it even down the street but I'm confident its all good.
 

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I fought the U101 code and every dash light possible for a long time. Eventually replaced the underhood fuse box and fixed everything. I suspect it was damaged internally.
 
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You say journey, can you provide a little back story? Was car hit? Water damage etc might help a bit to zero in on problem
 

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Discussion Starter · #5 ·
I fought the U101 code and every dash light possible for a long time. Eventually replaced the underhood fuse box and fixed everything. I suspect it was damaged internally.
I am leaning towards a BCM/ecu, bad ground, or wire, or something over the fuse box being bad. I will not rule out that possibility. Thanks for the suggestion.

You say journey, can you provide a little back story? Was car hit? Water damage etc might help a bit to zero in on problem
I say journey because with only Sundays being my only day to work on the car, its been a 2 year process to getting this car on the road. I bought car salvage. Car was missing a LOT of things. Replaced it all to find out it had a bad bottom end, not to mention a bad torque converter. I had the trans completely looked over by the dealership and they said everything was good with the exception of the TC. I replaced the bad engine with a new LSX37, bought a new TC and swapped over the aftermarket parts. I am hopefully ruling out the TCM being bad as they would have replaced that or told me.

Have you checked the trans range sensor?
Nope. I don't really know much about the car other than what I have worked on and general terms when it comes to cars/trucks in general. What does this trans range sensor do and what happens when its bad?
 

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Trans range sensor is what what the linkage hooks to on the side of the trans, when it goes bad the car doesn't know what gear it's in and causes a bunch of issues. There's is also likely a contact circuit in the gear selector itself that could get dirty, however in my experience if it were just the prndl lights on the dash because of a bad bcm or something, the abs and traction control would likely not give a fuck because the ECU/TCU would still be getting info, so in my opinion I'd be checking connection the the range sensor, maybe getting a schematic and ohming out up the the main ecu connectors. Or see how much a range sensor is and try it... I don't throw parts at customers cars, but sometimes on my own stuff if the parts are sub 100 dollars it's worth it to me, because that hundred could end up saving me 3 or so hours on digging through paper and harness. Time is money! Lol
 

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The fuse block was a common source of mystical errors and dash lights for many people.

You also probably need an alignment to clear the suspension codes that will pop up whenever you drive it for more than a few minutes.

Sent from my SM-G991U1 using Tapatalk
 

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Discussion Starter · #9 ·
The fuse block was a common source of mystical errors and dash lights for many people.

You also probably need an alignment to clear the suspension codes that will pop up whenever you drive it for more than a few minutes.

Sent from my SM-G991U1 using Tapatalk
Thanks Random. I'll remember that when I get to drive the car more than 20 ft back and forth in the driveway. 🤣

Just searching through some parts diagrams I don't see where the range sensor is on the 6L trans lineup
I thank you for doing some research. Would I come to the conclusion that the 6L doesn't have that sensor? I can ask the guy who went through my transmission and see what he says as well. 👍
 

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Discussion Starter · #10 ·
I just went through a bunch of pictures to find if I had any video of the car previous. I found one of the car before I pulled the engine and trans. I didn't have any dash lights on with the car running and the P for park was lit up showing what gear it was in so there is hope it is something simple. I couldn't imagine something would go the other direction. Took it apart to fix it not to break it. 🤣
 

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I'm assuming the range sensor is inside the trans on these, maybe make sure all the pins are secure in the big plug on the trans, maybe one of the pins pushed out the back of the connector when you put it back together?
 

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The range sensor is located inside of the transmission above the filter next to the valve body. I had to change mine in my V2, as it could not communicate with the BCM, ABS, ECM....etc....the same issues the OP is having. Cost for the switch from GM is $20-$30 dollars.
 

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Discussion Starter · #13 ·
I'm assuming the range sensor is inside the trans on these, maybe make sure all the pins are secure in the big plug on the trans, maybe one of the pins pushed out the back of the connector when you put it back together?
Good idea. That will be on my list for this Sunday. Thanks

The range sensor is located inside of the transmission above the filter next to the valve body. I had to change mine in my V2, as it could not communicate with the BCM, ABS, ECM....etc....the same issues the OP is having. Cost for the switch from GM is $20-$30 dollars.
Do these sensors just go bad out of no where? What causes them to crap out? 20 to 30 bucks doesn't sound like much but the labor, time and other parts...crap. It is what it is. I will pull the trans again if I have to. I wish I could know for sure. I guess a scanner would be the only way right? Thanks!! I appreciate the feedback. 🍻
 

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If the sensor is right above the filter in the pan I'd just throw one in for 30 bucks. They go bad because every time you move the shifter it's moving the sensor, more like a mechanical switch. I can't comment on the 6L sensor but the old 4L sensors were on the side of the trans, and they used to shit out all the time.
 

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Discussion Starter · #15 ·
If the sensor is right above the filter in the pan I'd just throw one in for 30 bucks. They go bad because every time you move the shifter it's moving the sensor, more like a mechanical switch. I can't comment on the 6L sensor but the old 4L sensors were on the side of the trans, and they used to shit out all the time.
Thanks. I will have someone at the parts department verify where its located and I'll research it.
🍻
 

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That's the part number, and the white box looking thing is it. In the PDF I attached below there's a line up procedure for installing. Not sure if there is a way to test the switch or not, but like I said for 30 bucks what the hell.
 

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Discussion Starter · #18 ·
That's the part number, and the white box looking thing is it. In the PDF I attached below there's a line up procedure for installing. Not sure if there is a way to test the switch or not, but like I said for 30 bucks what the hell.
Thanks. I talked to the guy who took care of my transmission and apparently, he never told me that they replaced my TCM when the guy looked at my transmission. DOH!! He was like...it was part of the money I paid. I told him that no one told me it was replaced I just paid for the work. The invoice never said the TCM was replaced. He said we call it a valve. How was I suppose to know. Long story short, the guy came over and programmed the TCM and now all is well.
I can't thank you enough for the help though. It helped me get to the bottom of the problem and I now have more knowledge in the future!! 🍻
 

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Discussion Starter · #20 ·
😄😄 Glad to hear you figured it out.
thank you. So am I. I wish I would have known that from the beginning. I feel like I have wasted the time of those that have generously helped me with the troubleshooting. I feel bad. But, the receipt did NOT say TCM so I can't say that I was fully aware. 🙃
 

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