LS factory cruise control hook up

[XwalkerX]

just hooked up all the wires again and with the key on im still getting a reading of 7v at the wire for pin G where it connects to the brake lamps. this is causing not only a noticeable draw on the battery via my voltmeter but also causing a very faint brake light to be on all the time.

still with key on and taking readings at the module with the connector plugged into it im getting these readings

a- 0v (toggle switch is in the off position)
b- 0v
c- 0v
d- 12v
e- 0v
f- 12v
g- 10v
h- n/a
j- 0v
k- 9v

[XwalkerX]

also id like to test the VSS output wire. mine is a black wire but its the only wire on either connectors at pin 50. my truck does have a custom harness on it but I would think the PCM still needs the wires in the factory position.

anyway since I cant find an answer via google...what should the VSS output wire read with the key on? should it read differently with the engine actually running? I understand it will send a pulse signal *while driving* but im not sure if there should be any voltage on this wire otherwise.

[ls1nova71]

I don't think you'll get any voltage on the VSS wire with the key on or just idling, pretty sure you need to be moving and it will be an AC voltage. This evening I will unplug my cruise module on my truck and test them to see what they are supposed to be and then we can compare the readings.

[XwalkerX]

thanks man

this has really stumped me

and again I only get these strange power bleeds when the connector is plugged into the cruise module itself with key on which is why I was questioning if its actually working correctly. the seller claimed it was working good prior to removal?

[ls1nova71]

Ok, I just checked two of my cars and they are both the same as yours. I get 9.8v on the VSS wire, so that must be normal. I also get 9.5v on the G wire with the module plugged in and that wire not hooked up. I checked it by unplugging the module then plugging in another pigtail and running the wires from it to the original plug, that way I didn't have to cut anything. Pay no attention to the colors, the second plug is actually a TAC module plug as they're the same plug and it's all I had.

You say you are getting very faint brake lights? Are you using LEDs?

[XwalkerX]

not using LED's but I do notice faint brake lights and also notice a draw on my voltmeter when I hook the g-wire up to the brake switch.

[XwalkerX]

I mean thinking about this it would make sense that my brake lights are illuminating because im sending 9-10v to that wire which should only become hot with 12v (turning on the lights) when the pedal is depressed.

would adding a relay here help cure this? similar to what people have to do with LED tails?

[XwalkerX]

Nova What's your voltage reading where the G wire ties into the brake switch wire? Do you also show 9/10v there?
Posted via Mobile Device

[ls1nova71]

Originally Posted by XwalkerX

not using LED's but I do notice faint brake lights and also notice a draw on my voltmeter when I hook the g-wire up to the brake switch.

I don't know why it does this, but mine do it too. I'm a mechanic, not an electrical engineer by any stretch. I can usually get things to work the way they are designed to work, but don't always know why they work the way they do.

Originally Posted by XwalkerX

I mean thinking about this it would make sense that my brake lights are illuminating because im sending 9-10v to that wire which should only become hot with 12v (turning on the lights) when the pedal is depressed.

would adding a relay here help cure this? similar to what people have to do with LED tails?

You would think my brake lights would be on too, but they aren't. I do know modules can do some weird things, but if you were sending 9-10v to the brake lights, you'd see more than a faint glow, they would be obvious that they were on. I would think even 7v would be pretty obvious. Adding a relay won't do a thing for it.

Originally Posted by XwalkerX

Nova What's your voltage reading where the G wire ties into the brake switch wire? Do you also show 9/10v there?
Posted via Mobile Device

I only measured it where I had the extra pigtail hooked to the original one, but since that wire only goes straight to the switch, it has to have 9.5v there since there's pretty much no way you'll get very much voltage drop from a 6 foot long wire.

What is this going in? And how are you testing it? Actually driving it?

[XwalkerX]

the basics from my swap are

L33 5.3
earlier 2wd 4L60e
99-02 PCM
99-02 Cable TB
prevatt harness
dakota digital speedo drive
dakota digital tach signal converter
old air a/c







the truck drives just fine.

im testing it every which way i can with a multimeter.
i tested all the leads with the key on and the key off
im testing voltage at the connector when its unplugged from the cruise module
im testing voltage at the connector when its plugged into the cruise module
im testing the wire tie in points with the connector plugged in and unplugged
etc etc.

i think im going borderline insane because i cant figure this out...

[ls1nova71]

Nice looking truck! What I meant though, was are you checking the function of the cruise by driving it? Or is it in a garage on jack stands?

[XwalkerX]

well i take it for a spin around the block and get up to 40mph then try to engage the cruise.

i turn on the power toggle then hit the momentary for the set function but it doesnt engage -____-

[ls1nova71]

Did you try hitting the resume side of the switch just in case you have them backwards?

[XwalkerX]

yeah tried both ways.

even tried with the power toggle in on and off positions

[ls1nova71]

Ok, just wanted to check. So you are using a GM brake light switch with the two sets of contacts, correct? What you might try now is adjusting the brake light switch in a little bit. Sometimes the two sets of contacts in them will be off a bit and although the brake lights may not be on with the pedal released, the other two contacts may not be closed. Adjusting it in so you have to press the pedal a little farther to make the brake lights come on might help.

[ls1nova71]

If that doesn't help, then unplug the connector and test pins E and D. Put the ground probe of the multimeter on pin E and the positive on pin D and make sure there's 12v. If you do have 12v, then while still checking those two pins, have someone press the brake pedal and see if it goes to 0v.

[XwalkerX]

so when i was going through the whole initial freak out about the extra voltage at the g and k wires i completely disconnected them and then took readings at all 4 leads coming off the brake light switch (and yes the GM one) the brake light switch is currently functioning great.

(key on)
first set of contacts:
lead 1= constant 12v [this is tied into pin F]
lead 2= 12v until the pedal is pressed then it cuts voltage to 0v [this is where pin D is plugged into]

second set of contacts: (which runs the brake lights)
lead 1= constant 12v
lead 2= 0v until the pedal is pressed then it reads 12v [this is where pin G is connected]

[XwalkerX]

youre saying test E and D on the connector side where it plugs into the module?

ill even try to test it with someone stepping on the pedal to make sure voltage cuts with pedal pressed.

[XwalkerX]

also if i havent mentioned it before im VERY grateful that youre helping me troubleshoot this

[ls1nova71]

Originally Posted by XwalkerX

youre saying test E and D on the connector side where it plugs into the module?

Yes, on the plug it's self, not the module.

[XwalkerX]

ok standby.

[ls1nova71]

Originally Posted by XwalkerX

also if i havent mentioned it before im VERY grateful that youre helping me troubleshoot this

No problem. Just to be sure though, everything is connected up now, right?

[XwalkerX]

Originally Posted by ls1nova71

No problem. Just to be sure though, everything is connected up now, right?

Everything is wired up as it should be currently

Here is the test with key on at points D and E

Posted via Mobile Device

[XwalkerX]

Also here is a pic of the faint brake light symptom

[ls1nova71]

So you have 12v between E and D, that rules out it not being grounded. Did it drop to 0v when the pedal was pressed? As for the brake lights, that's just odd, never seen that before, but do they go out when you unplug the module? Do they go out when you turn off the on/off switch?