Hey everyone. About two weeks ago I picked up a 2007 Type-S (6MT) with about 211,000 miles as a project. The car runs and drives, and had several parts replaced shortly before I purchased it including: clutch kit, timing belt/water pump, spark plugs, and motor mounts. I also have a 99 TL (A/T) with about 285K miles, but I have no experience with the topic I'm about to inquire about. I did some googling and searching here, and I did come across a thread started by "little brad" some time ago, but my symptoms are not quite the same.

The VSA light. This damn, pesky VSA light. I have the Triangle symbol light on, which is constant, and then the VSA illuminates as I begin to drive. Accompanied with this, and I'm assuming to be related, is a speedometer issue. The speedometer is erratic and jumps all over the place. Seems to get worse under heavier acceleration, and yesterday it just stopped working and read 0 for some time before bouncing back up again. The CEL is not on. However, I do have trouble code 84-33 for "VSA sensor neutral position not writing."

From my research I figured a wheel speed sensor had gone bad. I did some live data logging, and it appears that the sensors are working, and seem to be concurrent with each other in value. However, upon reaching about 30 mph, I lose all live data, and the values read as "N/A". I duplicated this twice. I will post a link to the video of the data log and speedometer below. Is it possible that one or more of my wheel speed sensors are actually bad? Why am I losing input to the scanner tool once I hit 30 mph? I'm also wondering if maybe I have a bad input or output speed sensor on the transmission? Thanks for any input guys, I appreciate it.

 

Under the "diagnostic info" screen on your nav display, it should show you the VSA code.
When my VSA light & "!" light illuminated 5 years ago, I was throwing a "code 25; yaw rate sensor". Changed out that bad boy, and the lights never came back.


Although I don't ever remember having a problem with the speedo so you're problem probably isn't the same as mine, just tryna help you diagnose it.

 

@TLDontFailMe

1. Did you perform the "VSA sensor neutral position memorization"?
2. Can you communicate with the VSA module with the scan tool before & after it glitches? Do any other modules stop communicating after glitching?
3. Did you do a visual inspection of the VSA module for a loose connector or corrosion?
4. The speedometer (gauge cluster) is connected to the ECM by the CAN line. The VSA module is also on the CAN line. It's possible that the VSA module is messing with the CAN line, which will cause those errors. You will need to diagnose to confirm.
5. Keep this in mind:
   1. Output speed sensor ---> ECM ==CAN==> Speedometer
   2. Wheel speed sensor ---> VSA ===> CAN line
6. Did you graph all the speed sensors while driving to 30mph to see if there is some erratic behavior?

07/08 ETM diagrams:


Gauge Cluster

CAN



VSA circuit diagram










VSA DTC

 

Well as of a couple days ago it actually threw a code of p0720 for the output (countershaft) speed sensor. I already ordered the replacement OEM part and I'll post an update once it's installed. Thanks guys

 

So after the install of the output speed sensor, the speedometer is functioning properly again, however now it's complaining about the input shaft sensor (p0715). The VSA lights are still illuminated. @El_Cheapo I'm not sure how to do the VSA neutral position memorization. I'm using an XTool D7 scan tool, and it doesn't seem to have that function...?

 

I'm not familiar with that scan tool, but it looks like it's a bi-directional scanner so it's probably in the "generic functions" or "special functions" of the ABS menu, but you may need to dig around in other menus to find it. 🤷‍♂️

I know for certain the Snap-on and Bosch scan tools can do it. The Launch scanners could not do it, but that may have changed with updates.

You can see if this is helpful:

 

I appreciate it @El_Cheapo. I ended up purchasing a bluetooth scan tool from Autel for about $60, which had the VSA communication function. I was able to get the VSA to re-learn, and now the light is finally out! Great little scan tool.