GMPP 525Hp LS3 with T56 SuperMagnum and Dakota Digital DBW Cruise Control

[WesB]

All,

I have a fresh 70 Nova build with a GM Performance Connect and Cruise LS3 with 525 HP. Also has a Tremec T56 Super Magnum as part of the package.
Instrumentation (HDX for Nova) and Cruise are both from Dakota Digital. All the instrumentation is working correctly and accurately.

The shop that built the car, Metal Brothers, and Dakota Digital have been doing their best to get the cruise to work with no joy.

With the cruise turned on and attempting to set the speed, the indicator light comes on on the dash and goes right back off.

Has anyone else with this combination had an issue with getting the cruise to work? Did it plug right in and work or did you have to make some adjustments?

Wes

[Z06vet]

I would look into the brake light circuit, that's where I've had problems in the past. Also, if you're running led bulbs, there is an alternative wiring sequence. Just 2 things to check off top of my head.

[130fe]

Are you getting a correct VSS signal to the DD unit?

[WesB]

ZO6 and 130fe, thanks for the replies.
I am running LED lights. I'm pretty sure the shop had to wire a relay into the cruise circuit for it to work with the LEDs.
I'm going back to the shop in the morning. I'll get them to verify the brake light wiring and the VSS signal.

David Kountz, the shop owner, has a Connect and Cruise drivetrain with the same pedal as mine in his Nova wagon. They are going to swap his pedal with mine and see if that works. If it is we'll know it's the pedal. If not the search continues.

R/
Wes

[blitzer454]

I had a similar problem, for me the problem was with the clutch switch. I correctly had the switch wired to the clutch GND input since my switch goes to ground when I press the clutch pedal but the cruise indicator would sometimes come on and go right back off. I had to add a pull-up resistor since the clutch GND input is open drain which is not mentioned anywhere in the documentation. I also used the VSS signal from the E67 ECM and in order to get that to work correctly I changed the VSS pulses per second setting as it was setup for the connect and cruise automatic transmission which has different number of teeth than the T56 magnum. I also have LED taillights but I used a MOSFET transistor instead of the relay as I wanted to avoid the relay making a clicking noise every time I pressed the brake pedal.

[WesB]

Blitzer454,
That sounds like the issue we are having. When trying to set the cruise the light comes on and goes right back off.
I'm pretty sure the VSS is set to 4K. Is that the value you are using?

Thanks,
Wes

[blitzer454]

Yes, In my case the E67 ECM VSS feeds the VHX Dakota Digital gauges and I use the SPD OUT from the gauges to feed the CRC-2000 module. If I remember correctly the default setting for the VHX SPD OUT was 2K so I had to set it to 4K to get the cruise control to work.

[dhutton]

I had a similar problem, for me the problem was with the clutch switch. I correctly had the switch wired to the clutch GND input since my switch goes to ground when I press the clutch pedal but the cruise indicator would sometimes come on and go right back off. I had to add a pull-up resistor since the clutch GND input is open drain which is not mentioned anywhere in the documentation. I also used the VSS signal from the E67 ECM and in order to get that to work correctly I changed the VSS pulses per second setting as it was setup for the connect and cruise automatic transmission which has different number of teeth than the T56 magnum. I also have LED taillights but I used a MOSFET transistor instead of the relay as I wanted to avoid the relay making a clicking noise every time I pressed the brake pedal.

Awesome advice here. I would add that pull-up resistor. Open drains without pull-ups are bad news....

Blitzer should be on the DD payroll.... :>)

Don