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Stesso

Diagnose Transmission Communication

6:18
22:43
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At 6:18 in

LSA Swap 1972 Monte Carlo: Tried Going to Dyno..What Happened? (Bonus Kasey Kahne Race Shop Tour!)

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What happens here

With the car running again, the owner uses an Edge CTS monitor to check diagnostics. The monitor consistently displays a speed of 158 mph, even when the car is stationary. This reading is identified as the default value when the ECU has no communication with the Transmission Control Module (TCM). To confirm the issue is wiring-related, the car is put on a BendPak lift, and the owner connects a spare 6L80 transmission to the car's wiring harness. The 158 mph reading persists, indicating the problem is with the car's wiring leading to the TCM, not the TCM itself. Further testing involves unplugging the transmission harness, which makes the 158 mph reading disappear, confirming the wiring or connection as the root cause.

Goal: Isolate the transmission communication problem to the wiring harness

Tools and materials

  • Car lift BendPak — To elevate the car for underneath access and diagnosis
  • Car — The vehicle being diagnosed
  • Edge CTS monitor Edge — Displaying car diagnostics and confirming the 158 mph reading
  • Spare 6L80 transmission GM — Used for testing the car's wiring harness

What they say

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okay let's see [Music] yeah something must have melted because it still says we're going 158 so we're going to drive back to shop in first gear you literally saved the day that's what i'm here for you'll be able to find yourself on youtube now oh yeah you live around here i look right here oh really oh so you were just like coming home yeah literally okay i got to pick a good place to break down there are still good people don't believe the news oh i appreciate it no problem thank you sir i'll see you around i'm sure you will hopefully not sitting right here broken again okay [Music] well how about that gear or whatever it is right now well if we're gonna have a problem we're not gonna leave this open-ended so let's get under here and figure out if we can find any broken wires so i just unplugged this it wasn't already like that but i don't you know nothing seems to be a problem here but it's possible that something could be cut you know way up in here somewhere i just want this freaking transmission gone i want a stick manuals don't do crap like this no i want to i want to get rid of this stupid transmission what are you doing right now oh yeah we got all these new shirts here we got special edition north carolina version flag shirt for all you local yoke old north carolina people which is what i'm wearing right now we got these the darrell waltrip western auto tribute shirts uh we actually just picked those up today the video that will be at the end of this and the robert yates racing tribute shirt which yeah yeah how many four people now you know this these ones actually got printed in casey kane's race shop so we're gonna check that out too you can find these and the hat i'm wearing at stapletonautoworks.com and if you order a hat in your order like you know you can get shirts and stuff in the same package but there's a hat included in your order that means we have to put it in a box you get a free rowdy energy sample in your package let's figure out what's wrong with this car finally able to dive into this thing try to figure out what's going on with it i read that 158 miles an hour is the default value that will come up whenever the ecu has no communication with the transmission whatsoever and that's what's coming up on here so that means well if i read somewhere that someone said their ignition wire wasn't hooked up so that's why it was reading that so i just tested mine and it it has power whenever i turn the key so that's not that's not it there's…

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