1998 LS1 speedo signal
05-08-2014, 11:07 AM
#1
Teching In
Thread Starter
Join Date: May 2014
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
1998 LS1 speedo signal I apologize if this has been asked before, but I couldn't find it if so.
We're working on a customers LS1 swapped 1976 Corvette, and it's got an early (perimeter valve cover bolts) LS1 with a Richmond 6 spd. He's got an Autometer sport Comp electric speedo installed.
Does anyone know if the ecu input on the early LS1's needs a square or sine wave signal? Also, if it's a square wave signal, is it a 5v signal, and what is the pulses per mile they'd be set at originally? The AutoMeter speedo has a buffered output that sends a 1600ppm, 5v square wave signal, which I'd like to be able to just change the pulse per mile settings in the ecu to read that if possible? If the ecu needs a 5v square wave signal, we can tune the ppm to make his OBDII Bluetooth adapter work with the Ipad he has in the dash to monitor and control engine functions, dtc's, data log, etc.. Is anybody familiar with this?
The vehicle isn't in our shop today, so I can't hook our HP tuners to it, but thought I'd try to ask around.
Thanks!
We're working on a customers LS1 swapped 1976 Corvette, and it's got an early (perimeter valve cover bolts) LS1 with a Richmond 6 spd. He's got an Autometer sport Comp electric speedo installed.
Does anyone know if the ecu input on the early LS1's needs a square or sine wave signal? Also, if it's a square wave signal, is it a 5v signal, and what is the pulses per mile they'd be set at originally? The AutoMeter speedo has a buffered output that sends a 1600ppm, 5v square wave signal, which I'd like to be able to just change the pulse per mile settings in the ecu to read that if possible? If the ecu needs a 5v square wave signal, we can tune the ppm to make his OBDII Bluetooth adapter work with the Ipad he has in the dash to monitor and control engine functions, dtc's, data log, etc.. Is anybody familiar with this?
The vehicle isn't in our shop today, so I can't hook our HP tuners to it, but thought I'd try to ask around.
Thanks!
05-09-2014, 12:10 AM
#2
GM PCMs since early OBD2 use an AC sine-wave signal. A square wave or buffered signal won't work for a PCM. Those buffered outputs are for ABS, speedos, cruise control and other slave devices.
Where does your autometer speedo get the Vss signal from? If it's a stock type Vss you can splice to it and give Vss signal to the PCM (in parallel with the autometer speedo), I have done it and both the speedo and PCM work good
Where does your autometer speedo get the Vss signal from? If it's a stock type Vss you can splice to it and give Vss signal to the PCM (in parallel with the autometer speedo), I have done it and both the speedo and PCM work good
