Cruise Control - LQ4, cable drive, Dakota module

[SchreinerM]

Hi everyone. I'm in need of some help on cruise control. I'm honestly at my wits end with this. Any help is appreciated! Here are the important details:

Issue: cruise control box turns on and off, but cruise doesn't work

Hardware:
- 6.0L truck engine, cable throttle body
- Stock cruise box connected to the throttle body with stock hardware
- 4L60e trans
- Dakota HND-2 buttons in cab
- ECU was reflashed by Branden at LT1tech, stock tune with VATS removed

Wiring:
- Stock cruise module
- Pin A: connected to Dakota brown wire (on)
- Pin B: connected to Dakota green wire (set/coast)
- Pin C: connected to Dakota yellow (resume/accelerate)
- Pin D: connected to LS ECU C1 Pin 33
- Pin E: connected to chassis ground
- Pin F: connected to 12V ignition
- Pin G: connected to brake switch (12V when pedal is pressed)
- Pin H: not used
- Pin J: connected to LS ECU C2 Pin 13
- Pin K: connected to LS ECU C2 Pin 50
- Dakota HDN-2 module
- Brown: connected to LS CC module pin A
- Green: connected to LS CC module pin B
- Yellow: connected to LS CC module pin C
- Red: connected to 12V ignition
- White: connected to 12V ignition
- Gray: connected to 12V ignition
- Black: connected to chassis ground
- Pink: not used

Trouble shooting:
- "On" light on HDN-2 does turn on and off with "on/off" button on unit
- Pin A on LS CC module is typically 0V. When "on" button is pressed on HDN-2 module, this pin gets 12V.
- Pin B on LS CC module is typically 0V. When "set/coast" button is pressed on HDN-2 module, this pin gets 12V.
- Pin C on LS CC module is typically 0V. When "resume/accel" button is pressed on HND-2 modle, this pin get 12V.
- Confirmed continuity on all other connections using multimeter.

[SchreinerM]

Let’s see if I’m successful at posting pictures. LS cruise module is on the passenger side inner fender. Second picture is the Dakota HDN-2 module inside the vehicle.

And yeah, I know it’s not a C10. But this is only forum I visit and you guys were so helpful on my LS swapped ‘68 C10.

[66 C10 383]

ls1nova71 did an awesome job of doing a write up on the DBC cruise and what all it takes. He also did one for the DBW.

https://67-72chevytrucks.com/vboard/...d.php?t=511477

[A1971Blazer]

check to make sure you don't have some residual or bleed-over voltage from the brake pedal switch wire at pin G.
If there's any voltage there, it will not allow the CC to engage.

[SchreinerM]

Ablazer - thank you. Is that something I’d do with a multi meter? Just check to see if there’s any voltage at pin G when the brake pedal is all the way up? If there is voltage, would that mean I need a brake switch?

Thank you for the reply. This is driving me nuts!

[A1971Blazer]

Originally Posted by SchreinerM

Ablazer - thank you. Is that something I’d do with a multi meter? Just check to see if there’s any voltage at pin G when the brake pedal is all the way up? If there is voltage, would that mean I need a brake switch?

Thank you for the reply. This is driving me nuts!

The switch may be OK as long as you get 12v when you step on the brake, and no voltage without the pedal depressed.
Yes you can check at that pin for voltage, it should not have any until the brake pedal is applied.
Do you have LED lights or tail lights?
In my case, I have LED tail lights, for some reason there was a small amount of current bleeding over to them when the switch was on so that about 4 of the little LEDs were barely illuminating.
I put some resistors on them, that made them go off but I still could not get the cruise to work. I didn't know if perhaps the components were bad?

I also read in the thread that the Dakota digital switch was NC (normally closed) and that would not work with the factory module without using relays to change it to NO (normally open) operation. This may be the issue? Look thru that thread that's linked in post#3

To be honest, I got frustrated with it and just bought the DD kit with the module and the trun signal lever included. It works perfectly.

[SchreinerM]

Standard bulbs (no LED) for me.

Thank you again, I’ll check the voltage and will read the linked thread.

[cj847]

I think 71Blazer is right. I think DD makes their own cruise control unit that is wired up different than factory.

On my 67, I got a cable cruise from the junk yard off of a 2001 model. I wired it per factory and used some cheap switches from amazon. I think I have $8 in the switch panel. One switch for off/on and one dual pole for Resume/Accel or Set/Decell.

[SchreinerM]

Thanks CJ. I think I’ll wire it up just like you have it. That will verify there’s nothing wrong with the factory box, ecu, or wiring. Once I know that’s all correct, I can decide if I try and figure out the DD box in the future. I just want to drive this thing. Thank you!

[SchreinerM]

CJ - one quick question. Are your switches wired to send 12V when pressed or do they close the ground when pressed? For example, when you press the dual pole switch to the “accel” position, does it send 12V to the stock Cruise module pin or does it complete a ground to that pin?

[cj847]

I am sending 12v+ to the cruise control. This is the pin out I was working with. I think most are similar. On my switch panel I have 12v ignition power to the on/off switch. Coming out of it 12v goes to pin A and to the center of the double pole switch. Pin B and C go to the two poles.

[SchreinerM]

Got a little free time this weekend and rewired it to closely match your system CJ. I didn’t have a dual pole switch handy, so I used two momentary switches. The wiring is 12V into a rocker switch. The output of the rocker goes to three places: LS module pin A (on), one terminal on each of the two momentary switches. Momentary #1 is set/coast (second pin goes to pin B in the LS cruise box) and momentary #2 is accel/resume (second pin goes to pin C in the LS cruise box). I believe this wiring matches what CJ has proposed. Still no cruise unfortunately.

I also checked voltage at the brake switch (pin G in the LS cruise module) and there is a small amount of voltage when the brake pedal is up. Something around 15 mV. Any ideas how to make this zero?

[cj847]

I'll take a shot at it. It's a real crap shoot diagnosing over internet.

To work the cruise must have the speed signal, the brake signal, and the TCC clutch signal. Also, if you have LED taillights they sometimes do not have enough resistance and will prevent the cruise from engaging.

Here is another schematic to help explain.

[SchreinerM]

I do appreciate the help, this is so frustrating! Somehow this is more difficult than doing the entire powertrain swap. Dang wiring.

The speedometer in the car reads off the LS ECU signal. I assume that means the speedo signal is accurate. Is there any way I can confirm this isn’t the issue?

All of the lights on the car are incandescent, no LEDs.

Last year I hooked up a Snap On scanner from a buddy and varied the TC is properly locking and unlocking. I’ve since given the scanner back. Is there anyway I can verify it’s functioning as intended?

I should have mentioned, I do have HP Tuners if that makes a difference. In my limited time messing with HPT, I couldn’t find anything that showed TC or Cruise signals.

[cj847]

Where are you getting your TCC brake signal? If you look at the schematic you can see that it is the opposite of the brake light signal (normally open/normally closed)? There are different ways to wire it but the easiest is probably a new brake switch with two outputs.

Google TCC brake signal wiring for more details.