VSS wire tapped. No cluster. Weirdness.

[CookieRoe]

In my never ending quest to properly install my NAV, I tapped (after my main wire harness was replaced last year at the dealer) my VSS wire (red w/ yellow stripe) to one behind the HVAC controls. Good enough. Last time I did, I had no problems. This time, when I go into the service menu of the NAV, I get the following information: 0 pulses, but doing 66mph. WTF? That doesn't make any sense. On the HVAC display, "--" appears when you want to see Average speed and MPG readings. My cluster isn't installed, but thought this was interesting. My guess is that (seems obvious) the rest of the car doesn't "read" the VSS if the instrument cluster is not installed. So having the cluster out of the truck means the VSS signal is disrupted somehow, like a non-completed circuit? I didn't think it would matter,

Any Toyota or whatnot tech can explain this (just to know) ?

Thanks!

0 pulses @ 66mph. That's like saying your heart rate is at 0, but are alive and well.

VSS tapped.

I was going to post this in the electronics subforum, but thought it would get more exposure this way.

 

[4RunnerSeth]

In my never ending quest to properly install my NAV, I tapped (after my main wire harness was replaced last year at the dealer) my VSS wire (red w/ yellow stripe) to one behind the HVAC controls. Good enough. Last time I did, I had no problems. This time, when I go into the service menu of the NAV, I get the following information: 0 pulses, but doing 66mph. WTF? That doesn't make any sense. On the HVAC display, "--" appears when you want to see Average speed and MPG readings. My cluster isn't installed, but thought this was interesting. My guess is that (seems obvious) the rest of the car doesn't "read" the VSS if the instrument cluster is not installed. So having the cluster out of the truck means the VSS signal is disrupted somehow, like a non-completed circuit? I didn't think it would matter,

Any Toyota or whatnot tech can explain this (just to know) ?

Thanks!

0 pulses @ 66mph. That's like saying your heart rate is at 0, but are alive and well.

VSS tapped.

I was going to post this in the electronics subforum, but thought it would get more exposure this way.

Here is my guess.

With the cluster removed there is no load and thus no place for current to go and pull the signal low during the off time of the pulses. There is probably a bunch of noise generated on this signal when there is no load, so your HU freaks out a little.

 

[CookieRoe]

Here is my guess.

With the cluster removed there is no load and thus no place for current to go and pull the signal low during the off time of the pulses. There is probably a bunch of noise generated on this signal when there is no load, so your HU freaks out a little.

Sounds very plausible, thanks. The NAV's displayed speed of 66mph is accurate (I had a Garmin mounted to the windshield) and it read the same. Trip computer was also "on strike". I'm willing to bet money that it's the absence of the cluster causing this. When I get it mounted, I'll post results.

I just think its very interesting. A friend joked to me that b/c the cluster is out, it won't be registering the miles I travel. I sincerely doubt that.

 

[4RunnerSeth]

Sounds very plausible, thanks. The NAV's displayed speed of 66mph is accurate (I had a Garmin mounted to the windshield) and it read the same. Trip computer was also "on strike". I'm willing to bet money that it's the absence of the cluster causing this. When I get it mounted, I'll post results.

I just think its very interesting. A friend joked to me that b/c the cluster is out, it won't be registering the miles I travel. I sincerely doubt that.

This is true. The cluster is what holds the mileage. With it removed you are not putting miles on the odo.

 

[97BlackAckCL]

So you're getting this without the mileage/HVAC cluster plugged in? Did you try it with it plugged in? I have seen many times where if switches are unplugged the circuit isn't complete and things like this happen

 

[CookieRoe]

So you're getting this without the mileage/HVAC cluster plugged in? Did you try it with it plugged in? I have seen many times where if switches are unplugged the circuit isn't complete and things like this happen

HVAC display and controls are plugged in, but the instrument cluster is not. I can't plug the cluster in just yet. I'll report back

The NAV showing the mph must be due to the simple fact that this GPS tracks speed (as does my GARMIN unit). The pulses I believe is there to inform the technician that the VSS is functioning properly or communicating the way it should to the NAV.

How did I find all this out? Simple. When traveling on any given road, the map displays what road you are on. My Honda does this as well as my parents Lexus cars/suv. After installing the NAV, it didn't tell me what road i was on, which was WHEN I became suspicious something wasn't right.

 

[J.A.]

The cluster "conditions" the speed signal. You need it installed to see the pulses correctly. This quote is taken from my nav override page.

"The 4th generation 4Runner has four ABS Speed Sensors, one at each wheel. Each speed sensor generates four 5-12V pulses per wheel revolution and sends these signals to the Skid Control Electronic Control Unit (ECU). The skid control ECU processes these signals and sends them along to the combination meter. The combination meter conditions these signals into a more precise digital square waveform pulse signal via a transistor based waveform shaping circuit inside the meter itself. The pulse signal is then transmitted to the navigation system which determines the vehicle speed based on the frequency of these pulses.
"

Toyota 4Runner Factory Navigation Override and Unblock Bypass Module

 

[CookieRoe]

CONFIRMED. 4Runner without the cluster installed sends the trip computer bonkers. Also, NAV doesn't show what street/route/highway/whatever you are traveling on without a PROPER VSS signal. As you can see, MPG (VSS signal is needed for computer to calculate MPG) readout shows 24.3 and on the NAV, you can observe a white retangular box under the vehicle position icon. It reads I-76W, but this was the best picture I could take.

Also of note: Cluster DOES hold the mileage, NOT the ECU! I've had my cluster off and drove my truck for about 220 miles. When I installed the cluster, this increase was not shown.

:hatsoff: