Well it appears your wiring is right, so that makes me think it's the VSS signal isnt quite right. I have never tried to run one off an ABS sensor, so not much help there unfortunately. Just to make sure, you are testing it by actually driving it, correct? I've gone through a lot of trouble shooting with people only to find out they were trying to test it on jack stands!

 

Yes, I was testing it by driving it.
I'd imagine it would be testable on jack stands provided all the diffs were locked though?

The VSS signal is apparently working - I doubt the PCM would be able to interpret it and provide data otherwise and by it's nature an ABS signal is durable.

I'll try another roadtest in a bit - it may be that checking and cleaning everything has sorted it... if I'm lucky.

I read somewhere that on some of the 6.0 versions one of the brake signals is inverted from what is found on all other models?

 

GenIV the brake signals are reversed, but yours seems to be correct. As for trying to test it on jack stands, it wont work without a load on the wheels, it will exceed the set speed then try and back it off and it happens way too fast for the cruise to keep up.

 

Ah yes, didn't think of that.

 

Well I've just been for a road test and still no joy. What is the minimum speed it will work at? Is it possible to turn the cruise control off in the PCM settings? say for lower spec vehicles? I'm just wondering if it was never activated?

 

https://ls1tech.com/forums/conversio...iring-lq9.html

This is the thread where an NO instead of an NC is discussed.

What is Mitchel's?

 

I'm thinking that the next thing to do is to measure the resistance between pin 6 of the tac module and earth. I'm assuming it would need to be at least 7ohm as that's the resistance of a brake light bulb ( I'm assuming that brake bulbs in the USA are 21 watt?)

I guess I could also apply 12v to pin 6 as a double check - it should light the brake lights, yes?

After that I'm really struggling. the only thing I could think is to put relays in the momentary circuits as they don't get a clean 12/0v at present, it's 12 ( or charging voltage) and around 3/4v. I thought if I fitted relays, then that would give a clean NC when the button isn't pressed and the relay isn't energised.

If anyone has any suggestions as to why I'm not already getting 0v, I'm all ears!

 

Bit of an update...

Pin 6 has a resistance of 1.2ohms and if connected to a 12v feed, does illuminate the brake lights.

What's confusing me is that I've just measured a 21w bulb at 0.3ohm resistance but it should be around 6.8ohm according to my maths...

Well P=IV or P/V=I so current should be 21/12 = 1.75a

V=IR or V/I=R so 12/1.75 = 6.8ohm

What am I missing? why the discrepancy?

Does this then mean that the resistance on pin 6 isn't high enough?

 

You mentioned the CPP switch Seems they are wired differently in DBW vs cable.
https://ls1tech.com/forums/conversio...er-switch.html

 

I've since managed to connect my scanner so that it can read the various inputs. All of the switches are working correctly as far as the PCM is concerned with the exception of the CPP that I couldn't find a check box for.

From what I can tell, my 2006/7 Truck PCM should have an NC+12 to the CPP pin33. It's only some of the earlier cars that use a ground signal. Am I correct in that?

One checkbox is "CC Inhib SigCmd" and the result is "On"

So it appears it is getting a command from somewhere to inhibit cruise control, but where? Could it just be that the speed isn't high enough or does anyone have any other ideas?

 

What kind of scanner are you using? I assume its pretty decent since it shows cruise control data. I don't have my '07 swap anymore so I cant hook my scanner up and look at it, but I don't recall ever seeing a clutch pedal status on it either.

You are correct in that your set up does need a 12v signal and not a ground, that thread that was linked is referring to an F body LS1, they were different for some unknown reason. But, looking at my schematic, it looks like you need 12v when the clutch is depressed, not when released. So you might try unhooking the CPP switch and testing it that way, just don't push in the clutch if it engages. I know that you have to press the brake pedal at least once in an ignition cycle before the cruise will engage, I have personally tried it, by shutting the car off at speed on the highway and restarting it and not pressing the brake, and it wont set, press the brake pedal once and try it again and it sets, but not sure if the clutch has to be done the same in a manual tune, but would be worth trying out. Might try running the CPP switch wire to an available 12v source that you can temporarily hook it to while driving to test it out if it isn't easy to change the pedal switch.

BTW, Mitchell is a company that makes service manuals, Mitchell on Demand is just the online version, which is what I'm using. This is a pic of the schematic, but its too big to get the whole thing on one page and I cant link it, can only post screen shots, but you can see the CPP switch is open in the diagram.

 

Here's the top portion of the schematic that shows the TAC pin 6 wire going to a NO brake switch, and the 12v going to the CPP, notice the CPP switch is also NO.

 

I'm inclined to think they've drawn that incorrectly but I'll try as you suggest with a 12v source.
As far as I'm aware, the CHMSL/SLSV *should* be NO 12v as that's how the brake lights operate..

I've checked again and I'm definitely getting 12 at pin 6 with the brakes applied. For some reason though, my scan tool MAC MentorTouch ( same as BOSCH KTS 460 ) doesn't think it's getting a signal as "Stoplamppdlsw" shows as released regardless of pedal position.

I don't know if it's that or something else as it's still showing "CC Inhib SigCmd" result "On"

 

Yet another update...
It appears it IS now recognising the Stoplamppdlsw and it can be seen to operate fractionally before the TCC switch.

Still getting the CC Inhib Sigcmd On issue though.....