PCS - Erratic VSS

[denny]

On WOT my VSS values drops off and on, almost 20mph. This is causing downshift and other crap. Anyone got any ideas ?

The green is the VSS and the blue is the gears, you can see in 3rd the vss drops which cause the gear dropped to 2nd.

This is the setup.

I called PCS, they told me to double check the voltage I have set for close and wot throttle. I checked that and it seem fine.

A better pic:

 

[JSM]

Re: PCS - Erratic VSS

Thats an odd one, going from memory and still digesting my lunch I believe the PCS gets the VSS from the output shaft speed sensor on the transmission. That is all tied into the same harness that comes with PCS. I would check that connection and maybe swap or change out the TOSS sensor. They are like $20 new?

dielectric grease on connections to try?

Either that or you maybe getting a false signal from other info, try moving harness around away from other wires.

 

[turbodig]

Re: PCS - Erratic VSS

That VSS signal looks like input shaft speed. It follows RPM the way it would if you were shifting.

My bet is that there's a wiring snafu.

 

[denny]

Re: PCS - Erratic VSS

Thanks, I will double check all the wirings. Now that you mention it, the vss is falling off as soon as it shifts, didn't saw before. Part throttle is working ok, the problem is only at wot.

 

[JSM]

Re: PCS - Erratic VSS

Low battery voltage to the PCS?

I say its a wiring thing somewhere.

 

[denny]

Re: PCS - Erratic VSS

I had the VSS and TSS connectors reversed , I send the log file to Fred at PCS and he knew right away. Its working great now.