What relies on the VSS output?

[Stinkbug]

This is just out of curiosity, but I have trouble code P0500 that I will address (again) this weekend. This is a malfunctioning speed sensor. This has popped up for me a few times over the last 10-12 years and has been resolved each time by replacing the electronic VSS in the tail cone of my JB Conversions Super Short SYE.

This got me curious about what exactly relies on that speed input. Obviously, the speedometer and likely the airbag system needs it, but with the relatively simple 32RH transmission, I can't think of anything else that might use the input. Maybe something else in the computer.

Any thoughts?

 

[Claytone]

The PCM and cruise control

 

[Stinkbug]

The PCM and cruise control

I assume it all runs through the PCM but most curious about the systems that use the info.

So far we have:

1. Speedometer
2. Airbags
3. Cruise control (I forgot some trims came with that)

 

[Rickyd]

Torque converter lockup?

 

[LJGreg]

Rubicon Lockers

 

[TEZZA]

On 2005/6 models with the NGC3 PCM VSS is read to verify that the engine is no longer idling.
It is used for torque management, idle rpm vs speed adder, power enrichment delay,

 

[NskLJ]

This is just out of curiosity, but I have trouble code P0500 that I will address (again) this weekend. This is a malfunctioning speed sensor. This has popped up for me a few times over the last 10-12 years and has been resolved each time by replacing the electronic VSS in the tail cone of my JB Conversions Super Short SYE.

This got me curious about what exactly relies on that speed input. Obviously, the speedometer and likely the airbag system needs it, but with the relatively simple 32RH transmission, I can't think of anything else that might use the input. Maybe something else in the computer.

Any thoughts?

Evap system to purge fuel vapors

 

[hear]

Torque converter lockup?

I would love to understand the specific logic of when it turns on. Not that it's illogical today, I just want to understand it better.

 

[freedom_in_4low]

I don't know the mechanism, but it seemed like on my 99 (5 speed) there might have been something related to the IAC. When mine was disconnected, it would stall out just about every time I would come to a stop.

 

[Juggernaut]

I don't know the mechanism, but it seemed like on my 99 (5 speed) there might have been something related to the IAC. When mine was disconnected, it would stall out just about every time I would come to a stop.

The VSS tells the PCM when to transition to idle, which also affects spark and fueling. Depending on the year this may or may not be mapped out in HPT.