4l80 speedo tuning help
Thread Starter
TECH Regular
Joined: Jan 2007
Posts: 403
Likes: 17
4l80 speedo tuning help Hi, IM paying a local shop to tune my pcm. He made a house call and got my car running, but the Speedo is WAY off which is causing the car to shift funny.
When going 10 mph, the pcm thinks the car is going 100 mph. In the pcm, the tire size and gear ratio are set correctly. What is going on? Possibly the wrong 4l80e segment swap on my pcm?
When going 10 mph, the pcm thinks the car is going 100 mph. In the pcm, the tire size and gear ratio are set correctly. What is going on? Possibly the wrong 4l80e segment swap on my pcm?
I ran into this in a rock crawler ....but he only had one vss on his 4l80e and the issue was regarding the transfer case.
The 4l80 uses two vss sensors...maybe one is bad?
The wrong os will do this too......a vette tune in a truck pcm....I was called in to another shop On that one...i, started with the correct os and rebuilt...
The 4l80 uses two vss sensors...maybe one is bad?
The wrong os will do this too......a vette tune in a truck pcm....I was called in to another shop On that one...i, started with the correct os and rebuilt...
10 Second Club
Joined: Nov 2005
Posts: 933
Likes: 75
In the trans portion, make sure the pulses are set at 40. That will help. If it doesn't fix the problem, you will have to get the speedometer cluster pulses adjusted also. Mine is a GTO that I switched from T56 to 4L80. For my car there is a vzclustermod program available as a download free. I had to buy a ALDL cable for my computer to plug into the port on the car. I adjusted the pulses in the speedo and got the speed right on.
