Hypertech Spedo Calibration Box correcting Spedo, but not Cruise Control

Looking for anyone that has any experience or a wiring diagram that covers how the cruise control module gets its speed signal.

While getting 35's put on my truck, a plug-n-play Hypertech speedometer calibration box was installed that gets plugged in between the harness and instrument cluster. The speedometer calibration is perfect, but the speed that the cruise control displays in the instrument cluster is the uncorrected speed.

I am hoping I just need to take the output signal from the Hypertech module and run that to the cruise control module.

TIA!

 

What year Tundra do you have? When you are driving on the highway at a steady speed and turn the Cruise on does the displayed speed change? Then while in Cruise and you turn it off (I left my foot in the same place when I turned it on) does the speed change?

 

It is a 2018. The cruise works fine to maintain the set speed. The issue (yes... It is ticky-tacky...) is that if I want to set my cruise to 77 MPH, the spedo will read the accurate speed of 77 MPH, but the digital "Set Speed" that is displayed on the color LCD between Tach and Spedo will read something more like 72 MPH. Not sure what year they added the LCD to the gauge cluster

 

hmmm.. i havent noticed that with my hypertech. ill try it on the way home from today and get back to you. i have a 2017.

 

Yes, cruise control speed setting remain un changed. Set your cruise control with the speedometer only. I already contacted hypertech and they do not have a fix for it yet.

Yellow box will work everything since it's getting bypassed at the speed sensor before the ecm. Hypertech/rough country is after the ecm.

 

Thank you for the info and letting me know about Yellow Box.

Added pic to the thread just for reference if anyone wants to see what the Hypertech will look like.

 

I have the Rough Country but it uses the same software as Hypertech. It has the word Hypertech at the top of the program dialog box and my cruise setting and speedometer are in sync. Interesting, I have a 2018 Platinum

 

Do you have the Adaptive Cruise Control on your platinum? Someone said that you can change the speed-o-meter seating with the Entune Plus with GPS in the HUD.

 

I looked in the 2018 Owners Manual and Nav / Multi-Media docs and did not see a setting for GPS speed, only to set the time settings to sync from GPS. Maybe I missed something. For reliability I would expect the cruise "set speed" is matching what the ECU is getting for speed from the transmission since GPS reception can be spotty.

The radio is another device that should get a speed input signal to control the adaptive volume control and the "safety features" that lock the settings when the vehicle is in motion. I will enable the speed display on my Nav to see if it is getting the uncorrected speed from the transmission or if it calculating the correct speed from GPS. I expect the Nav is using GPS calculated speed.

 

Yes I have the Adaptive Cruise Control on my Platinum and I did not see anything in there to set the speed. When I get a chance I will go in with my Techstream and see if I can find anything.

I have been watching and my Cruise Control set speed is the same as my speedometer speed reading on the dash. I am not sure why yours is different except your hardware is Hypertech and mine is Rough Country

 

I have rough country as well. I'l try to update my hardware again and recalibrate.

 

That was the first thing I did was update the hardware because the 2018 hardware did not come when I purchased it. I also had a Hypertech that did not have the 2018 on it and I had to update the firmware. The Hypertech had bad wires and would not work so not sure what it would have shown on the dash.

 

I finally got around to pulling the instrument cluster to get to my Hypertech and then connecting to a PC. My module was running a 2.8 software version with a 3.5 Core version on hardware version 2.00. It right away prompted me that a critical update was available. The update took my Core software version to 3.7.

Hopefully something in there has fixed it! I did note in the configuration menu that the range for Tundras went 2014 - 2018 and that there is a 2019 - 2020 category.

I will be putting my differentials back in tomorrow after having East Coast Gear in Raleigh put some 4.88s in. Once the truck gets put back together and gets some miles on it I will update the thread.

 

Following...because as much as my brain says "stay OEM size", when I have to buy new tires I know my impulse control will reboot and I'll get larger tires...

 

Since the speedometer and odometer are accurate I have no regrets on the larger wheels and tires.

My truck is all back together but I need to wait another 12 hours for the RTV to set up before adding gear oil and taking it for a test run with 4.88 gears and the new Hypertech firmware. The configuration software for the Hypertech reported I was running a 1.044 scaling adjustment with the stock 4.30 gears and 35" tire. Changing to the 4.88 changed the value to 0.940, so if the cruise speed is still off it should be reading higher now.