G-Body

iTrader: (4)

What are the requirements to make it work? I am feeding +12 v to the cruise control on switch signal. A +12v momentary signal to the set/coast input. The TCC signal to the PCM is getting +12v until the brake pedal is depressed. But the cruise will not engage. I do not have the stop lamp switch signal hooked up, but that should not be a problem since it is just there to shut the cruise down right?

I am running a TH400 trans could that be an issue? I have a VSS signal being sent to the PCM and the trans codes are disabled in the PCM. Its out of a 2003 chevy suburban.

Pocket

iTrader: (22)

It needs the VSS input because its function is based off of speed rather than throttle position. The brake switch also needs to be attached. Both the N/O and N/C brake inputs are required

G-Body

iTrader: (4)

VSS is taken care of, I have a 93 caprice rear axle with the ABS sensor in the pig. Its sending a 22 pulse per rev signal to the PCM and the PCM was reflashed with HPTuners so the PCM is seeing the correct speed.

The N/C brake switch is hooked up and operational. I didn`t hook up the N/O switch because the buick cruise control switches already have their power hooked up through a brake switch. Figured the N/O switch wasn`t going to see power anyway till the brakes are depressed so I didn`t think that would be an issue getting the cruise to engage without it. I know the N/O switch is needed to shut the cruise off, but I wasn`t worried about that, cause when I step on the brake the whole cruise system loses power. Maybe I`ll try hooking it up tomorrow just for the heck of it.

busta9876

iTrader: (3)

n/o brake signal is required. tac module looks for brake light bulb resistance to ground at power on to ensure that circuit is good.

if not hooked up it will not work

G-Body

iTrader: (4)

That is ridiculous. Definitely whats causing the problem though , as I never hooked the N/O switch up. My luck the 78 buick electra that I`m putting this into will fall outside of the specified resistance range LOL.

busta9876

iTrader: (3)

so far the brake light circuit on my 67 pickup (2 bulbs total) has worked fine and my 89 caprice (4 bulbs).

original trucks, it used the circuit to the 3rd brake light, called CHMSL or (center high mounted stop lamp).. you'll see the wire called CHMSL feed circuit.

also, hopefully transmission type in the programming is still set to 4L60E and torque reduction during shift was set to 0. Setting trans selection to MANUAL trans will require PCM to have a clutch pedal switch input..which goes into the PCM on a different pin then TCC Brake switch....its the same signal...12v+ when pedal is released...and it opens the circuit when you press the clutch pedal.

G-Body

iTrader: (4)

Thanks. I hooked up the stop lamp circuit today and the cruise works great.

67Mal

What If I have LED tail/brake lights?
Could I maybe wire in a hidden CHMSL?

Thanks for the great info,
Malcolm

G-Body

iTrader: (4)

You could wire in a hidden CHMSL. All the PCM cares about is that it has the correct resistance to ground. An 1157 should have ~6 ohms of resistance so you may be able to hook up 2 10ohm resistors in parallel (= to 5 ohms of resistance) to ground and get it to work.

67Mal

I tied a 1157 into the circuit, the cruise went to working perfectly.
Now if I could keep that light from coming on under the dash when I
push the brakes.

I'll see if I can come up with some resistors.

Thanks everyone for all the help.
Malcolm

busta9876

iTrader: (3)

You should probably try a few different light bulbs. Trying to match the resistance of the 1157 with resistors, you'd need some fairly high wattage resistors. I found some specs for the 1157 bulb and some others...

http://cybrvanr.tripod.com/bulbspec.htm


the CHMSL used smaller bulbs then the 1157, I would image you could try a smaller bulb and it would work.

OHMS = volts / amps

or


OHMS = volts*volts / watts