Anyone know what the vss signal should be? ie: 0 to 5 v?

I'm not able to get the vehicle speed input working. I have a 02 f body pcm and using a us shift quick 4 controller for a 4l80e. The output from the quick 4 is working for the speedo. The speedo and quick 4 are showing the same and correct as speed

 

And what speed sensor are you actually using ? how many wires go to it ?

 

the original ones from the 4l80e. it came from a 99 2500 van with a 5.7. 9hpp was the code on the right side.

each vss has 2 wires to it.

i have both vss wired into the quick 4 per their manual, and installed a 10µF, 25v, non-polar capacitor to switch from a 0 to 5v signal to a -2.5 to +2.5 v signal, then split that wire to the vss high signal input and the speedometer in the dash.

i currently have the vss low signal input grounded.

 

A 2 wire sensor almost always produces a sine wave output. So no, it will not be a 0/5v signal like a digital/hall type sensor.

Trying to share a signal like that to multiple devices can often be dubious too, but a lot depends on the electronics inside each unit.

 

It's an AC signal, so you need a multimeter set to AC Volts. with the harness unplugged and the drive wheels lifted, put the trans in D ald let the wheels pick some speed.
The signal should be from 1 to 2 Volts, the higher the speed of the wheels the higher the voltage.

Why are you using an external controller if the 02 PCM is much better at controlling it?

 

Thanks, I'll get a helper and check that out. I went with a us shift quick 4 controller for the trans. I've never had luck tuning the auto in my previous car and just got frustrated with it.

 

In gear I see a constant voltage of 8.5. only time it changes is when I move the shifter

 

Then you either are not connected to the speed sensor, or you're doing something very strange.

And really you need a scope to verify the output of such a sender.

 

lol! it's frustrating....that's for sure

i tried changing all the signal output types from the quick 4 and no luck.

i think i'm going to ignore us shift and wire the pcm directly to the pcm like it's done oem. for some odd reason the quick 4 doesn't want to talk to the pcm, but it accepts the tach signal from the pcm no problem!

 

I havent even a clue what you're trying to do.

Were you not trying to get a speed signal into the quick 4 ?

Now you're talking about outputs from the quick 4 ?

And moving a gear stick can have no impact on a speed reading from any sensor

 

I'm trying to get the input working on the pcm. The output is coming from the quick 4.

Per us shift. I was instructed to ground the vss low signal input and connect the high signal input from the pcm to the speed output on the quick 4

 

What input though ?

You'd be better posting some drawings or links to instructions, as none of that makes sense.

 

From their manual
"Speedometer Output:
We have provided an adjustable speed signal output that can be used to drive
an electronic speedometer, if desired. Use of this output signal is not necessary,
but it can be helpful if your speedometer can not be driven correctly from
another source. This signal can also be corrected for different gear ratios and
tire heights, so it can be very useful in some applications. The speedometer
output signal is normally provided as a 5 Volt square wave, but it can also be
configured to provide a 12 Volt square wave when required (please refer to the
"jumper settings" document for more information).
There are two speedometer output modes that can be selected via the tuning
software or the built-in tuning interface. It can also be disabled if not used. In the
replicated speed sensor output mode, the speedometer output provides an
amplified and squared version of the original speed sensor signal. Replicated
mode is useful for applications that require a signal with the exact pulse rate of
the speed sensor being used. There is also an adjustable corrected mode,
which is very useful for correcting speedometer errors or providing unusual
speedometer output signal frequencies.
Adjustable mode is essentially the electronic equivalent of a ratio corrector gear
box for a mechanical speedometer. In adjustable mode, the correction factor is
entered as a decimal number. The correction factor is the frequency ratio of the
speedometer output frequency to the speed sensor frequency. This number can
be easily adjusted to synchronize the vehicle speedometer to a GPS or other
instrument.
In some cases, such as driving the input of an engine control ECU, the 0-5 Volt
(or 0-12 Volt) square wave signal will not be able to properly drive the device
that it is connected to. This is because some devices are only designed to
accept an input signal from a variable reluctance (magnetic coil) sensor.
Because of this, they may expect the input signal to swing below ground (0
Volts). To drive this type of input, use the included capacitor to "offset" the DC
value of the speedometer signal to 0 Volts. As a result, the driven device will see
16
a -2.5V to +2.5V signal instead of 0V to 5V. To make this signal work, install the
provided 10µF, 25v, non-polar, electrolytic capacitor inline between the
speedometer output of the Quick 4 and the device that it is driving. To install the
capacitor, cut the speedometer output wire and solder a capacitor lead to each
of the two cut wires."

So this is how I have the car wired

Speed out from quick 4 into the capacitor

split the feed from the capacitor to the speedometer in the dash and red pin 21 (vss high signal input) on the pcm

Their tech support said to ground the vss low signal input, red pin 20 on the pcm

both vss sensors are wired into the quick 4 per their manual/harness

 

Really to test any of this is giving a suitable signal, you need an oscilloscope.

Have you tried wiring the VSS to the PCM...without anything else to see if it actually works as normal ?

In the config above...does the speedo work correctly ? Is it the OEM speedo ?

 

You are complicating things more than needed.
Don't ground any wire from the Vss sensor. Wire it directly to the controller.

You can also splice the same signals to the PCM Vss input and both will work, or you can wire the Vss to the PCM directly then use the PCM speedo output for the transmission controller.

 

I went back and wired the the vss to the pcm against what us shift said, everything works now

The speedometer is part of a Dakota digital vhx gauge