Advanced VSS Th-350 Question
Advanced VSS Th-350 Question Hi, I have a 5.3 with a th-350 and am using an autometer electric speedometer. I purchased the GM autometer electric sender and wired it into the speedo and the instructions say for EFI applications to use the VSS out on the back of the gauge. There is only one pin for the VSS out on the speedo and the ECM has two wires: green and purple. Is this compatible? I do not want to change my tailshaft but have the option of using another speedometer-driven VSS sender becuase the autometer sender has an extra output for a speeo cable. I've searched but not have found much on this particular situation.
Joined: Sep 2004
Posts: 3,148
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From: Downers Grove, IL
This may or may not be compatible, what type of output does the speedometer put out. The computer is looking for a sine wave AC signal.
The ppl/wht wire on the harness is the high output from the VSS and the grn/wht is the low output from the VSS (basically a ground).
It may work if you connect the output to the ppl/wht wire, but only if the speedometer puts out a sine wave AC signal.
The ppl/wht wire on the harness is the high output from the VSS and the grn/wht is the low output from the VSS (basically a ground).
It may work if you connect the output to the ppl/wht wire, but only if the speedometer puts out a sine wave AC signal.
If you want to just keep the regular speedo gears, Magsensors.com sells a VSS that will screw onto the factory speedo output. I am going back to an automatic in my car and will be going this route soon.
When I put the autometer electric speedo in my monte I had problems with the pcm reading speed from the output of the speedometer to the pcm. It's been a few years ago so i do not remember if the input to the autometer is one wire from the vss or both wires. But what I wound up doing was leaving the vss tied into the pcm as it is from the factory that is straight from the vss to the pcm and then just t-d the autometer wiring into the factory yellow and purple and it worked. I just ignored the pcm out terminal on the speedometer. It's not how the instructions say to do it but since I started off with a 4l80 before going to a th350 that was the only way I could make the tranny shift correctly and make my cruise work right. On the diagram I remember it read vss high and low on the yello and purple. I tied the signal to the speedo to the high wire. It took some tinkering but I got it to work autometer tech was not very useful.
