No VSS so won’t shift
Thread Starter
Registered User
Joined: Jun 2024
Posts: 1
Likes: 0
No VSS so won’t shift I am installing an LS1 and 4L 60 E into an old Buick. The engine and transmission came out of a 2004 GTO. It starts, runs, but will not shift out of first. My scanner shows no speed signal and also no codes. My HP tuner confirms this. Using a multimeter to measure AC voltage I confirm that I am getting a signal from the VSS at the wiring going into the ECU (pins 20 and 21 on the green plug) as the wheels turn. I tried swapping out ECU‘s with the same tune and get the same results. Can there be something in my tune that is not processing the VSS signal?
I "think the E40 PCM gets the VSS signal through serial data.
Luckily, I haven't had to mess with one of those bastards PCM's in several years and can't remember how it works.
Luckily, I haven't had to mess with one of those bastards PCM's in several years and can't remember how it works.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
Yeah, this is the common "Blue Green" PCM. Just checked and Pins 20 and 21 to the Green connector are the VSS wires. No, there is no tuning parameter to disable the VSS signal.
When you say you are getting a signal, do you mean with a scope or just a volt meter? What voltage are you seeing? (Does anyone know what voltage he should see?)
Have you tried another VSS?
When you say you are getting a signal, do you mean with a scope or just a volt meter? What voltage are you seeing? (Does anyone know what voltage he should see?)
Have you tried another VSS?
Trending Topics
Teching In
Joined: Jun 2009
Posts: 9
Likes: 0
From: Half Moon Bay, CA
Yeah, this is the common "Blue Green" PCM. Just checked and Pins 20 and 21 to the Green connector are the VSS wires. No, there is no tuning parameter to disable the VSS signal.
When you say you are getting a signal, do you mean with a scope or just a volt meter? What voltage are you seeing? (Does anyone know what voltage he should see?)
Have you tried another VSS?
When you say you are getting a signal, do you mean with a scope or just a volt meter? What voltage are you seeing? (Does anyone know what voltage he should see?)
Have you tried another VSS?
nt up and down as output shaft RPM changed. I’m attaching my tune if you’d like to dig deeper.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
12 Second Club
Joined: Dec 2017
Posts: 1,030
Likes: 220
From: San Antonio
It might be the VSS Pulses per mile settings. I was just comparing yours to my old 4L80 file. The pulses are completely different. It looks like you are using a 4L60, so it might need to be different. I also just compared your file to a 2005 5.3L with a 4L60. The pulses are different from those 2 files as well.
I'm looking at the pulses, because the transmission shift schedule goes by speed (mph). The pulses determine the mph signal. If you aren't getting enough mph, then the trans won't shift. The stock settings should work if you kept the engine, trans, and PCM together. If you mix and match PCM, engine, and trans, then you might have issues.
I'm looking at the pulses, because the transmission shift schedule goes by speed (mph). The pulses determine the mph signal. If you aren't getting enough mph, then the trans won't shift. The stock settings should work if you kept the engine, trans, and PCM together. If you mix and match PCM, engine, and trans, then you might have issues.