Wondering if anyone has come across the issue I'm having with trying to setup the VCM-101 Dakota Digital box for cruise control. The issue is that the 6L80 does not seem to output a speed signal to the OBDII port. I first ran into this issue when trying to get a speed signal out of the OBDII port while doing a dyno tuning session. The guy operating the dyno could not find a speed signal and mentioned that he had never come across this problem with a LS3 and 6L80E connect and cruise setup. Anyway, the vehicle runs, drives and shifts fine and I'm getting the speedometer signal from the transfer case so it's not an issue except for trying to get the VCM-101 to work. I have it configured to get the speed signal from the OBDII but it's not getting any signal. Can I tap into the Toyota speed sensor on the transfer case and run a wire to the "speed" input on the VCM-101? If so, which wire would be the correct one. Thanks in advance for any advice
Using Dakota Digital VCM-101 for LS3/6L80 Swap
- Thread starter venom69
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My VCM-101 Dakota Digital just arrived today. So, I will be figuring this out very soon.
Your ECM should have a pin for speed. I think pin 39. It might not be pinned in your harness.
Is your TCM connected to the OBD2 port? Can you get gear information?
Look at the Toyota EWD for your year. SPD goes to speedometer, and then to the Toyota ECM. In my EWD, it is ECM connector E7, Pin 8. It is there where I would pull the signal if you can't get it any other way. No need to splice anything since that connector shouldn't haven't anything connected to it.
It might be found at the original Toyota Cruise Control computer as well.
Your ECM should have a pin for speed. I think pin 39. It might not be pinned in your harness.
Is your TCM connected to the OBD2 port? Can you get gear information?
Look at the Toyota EWD for your year. SPD goes to speedometer, and then to the Toyota ECM. In my EWD, it is ECM connector E7, Pin 8. It is there where I would pull the signal if you can't get it any other way. No need to splice anything since that connector shouldn't haven't anything connected to it.
It might be found at the original Toyota Cruise Control computer as well.
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Thanks for the reply. I ended up called GM Performance and they mentioned the speedometer output wire in their harness. I found it and routed and connected it to the VCM-101 "speed" port and then changed the input from OBDII to "signal" and set the PPM to 4000. Didn't work. Still no speed signal. Also tried the "learn PPM" process in the VCM-101 setup (drive a mile to calibrate). Didn't work. Still no speed signal. My Toyota speedometer does work so I might try and use that wire for the speed signal. Not sure why the Chevy one didn't work. I'm going to call Dakota Digital again tomorrow.
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- #5
I think you might have hit on it. I did a bit of searching and it looks like it might need a resistor to convert the Chevrolet sine wave output to a square wave. I had a friend mention that he ran into a similar issue installing a Dakota Digital instrument cluster.
From Google: Connecting the 6L80E speedo output from a GM Performance Connect and Cruise harness to a Dakota Digital VCM-101 (Velocity Cruise Commander) typically requires a 1k-ohm to 5k-ohm pull-up resistor to produce a clean square-wave signal that the VCM unit can read.
To create a usable signal, install a 1K-5K resistor between the Speed Input wire and a switched 12V power source.
From Google: Connecting the 6L80E speedo output from a GM Performance Connect and Cruise harness to a Dakota Digital VCM-101 (Velocity Cruise Commander) typically requires a 1k-ohm to 5k-ohm pull-up resistor to produce a clean square-wave signal that the VCM unit can read.
To create a usable signal, install a 1K-5K resistor between the Speed Input wire and a switched 12V power source.
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- #6
Just a note to close this out since I got it working today. Two main issues were the problem. The first was that you do need a pull up resistor for the GM speed output signal. According to GM tech support, a 5K ohm resistor is needed. As it turned out, despite buying a variety pack with 24 different size resistors, the one I bought did not come with a 5K so I used a 6.8K. I told the GM tech I had tried a 2.2K and he aid it needed to be at least 5K which is why I went with the 6.8K. The other issue was completely my fault. I failed to connect the speed output connector at the transmission to the main ECM harness. For the connect & cruise harness, there is a short (12"), 1-wire lead coming from the back of the transmission. I had not connected it since I was using the Toyota transfer case speed output signal to drive the Toyota speedometer. The harness also has a long (72") 2-wire connector that needed to be connected to the one at the transmission. I had bundled mine up and tucked at the back of the intake so it took me a few minutes to find it. Once I did that, I started to register speed in the Dakota Digital app for the VCM-101 module. The speed signal will still show red until you reach 35 mph, but then it goes green meaning you can then set the cruise control.
On a side note, I ended up removing the Dakota Digital harness from the OBDII port to the module since it is only needed for tach and speed output which I wasn't using. The brake switch is hard wired, the drive-by-wire throttle has it's own harness, power and ground are hard wired and my speed signal is hard wired from the Chevy harness. Confirmed with Dakota Digital tech support that it wasn't required if getting those signals elsewhere. I wanted to get rid of it since I have a scan gage that I normally have plugged into the OBDII port.
On a side note, I ended up removing the Dakota Digital harness from the OBDII port to the module since it is only needed for tach and speed output which I wasn't using. The brake switch is hard wired, the drive-by-wire throttle has it's own harness, power and ground are hard wired and my speed signal is hard wired from the Chevy harness. Confirmed with Dakota Digital tech support that it wasn't required if getting those signals elsewhere. I wanted to get rid of it since I have a scan gage that I normally have plugged into the OBDII port.
I looked at the wiring today.
I also think the OBD2 isn't needed, other than maybe tach signal to prevent over revving. That is more of a concern with a manual transmission anyway.
I plan on pulling most of what I need from the Toyota Cruise Control Harness. It has almost everything needed...
The lower the resistor, the more effective the voltage pull up will be. However, you want as high a resistor as possible to reduce current draw. If 6.8K works, then stay with that.
You can put resistors in parallel to reduce the total resistance.
Two 6.8K resistors in parallel = 3.4K.
Two 2.2K in series = 4.4K
Two 6.8K resistors in parallel + One 2.2K in Series = 4.8K
I also think the OBD2 isn't needed, other than maybe tach signal to prevent over revving. That is more of a concern with a manual transmission anyway.
I plan on pulling most of what I need from the Toyota Cruise Control Harness. It has almost everything needed...
The lower the resistor, the more effective the voltage pull up will be. However, you want as high a resistor as possible to reduce current draw. If 6.8K works, then stay with that.
You can put resistors in parallel to reduce the total resistance.
Two 6.8K resistors in parallel = 3.4K.
Two 2.2K in series = 4.4K
Two 6.8K resistors in parallel + One 2.2K in Series = 4.8K