slosteve

Desperate meaning I've come to this forum searching for info on my non LS engine swap; its a 4.2 or 4200 Atlas inline 6 out of a GMC Envoy/Trailblazer that I believe uses the same PCM, which my tuner calls a P12(stamped on the rear plate). It's a DBW system.
Anyhow, I put this engine with it's 4L60E into a '54 Chev sedan delivery and it runs great. The PCM has been reflashed and the harness redone with the cruise leads left intact. I contacted Dakota Digital regarding a usable control which they researched and found their HND-2 normally open unit would work and drew out a wiring diagram. I've got it all hooked up, the control sends voltage to the proper pinouts at the correct times, but the cruise just won't work. My tuner/harness guy says it 'should' work and he's done others that do; he's sent me 3 PCM's and none of them will run the 'cruise'.
Anybody have suggestions?

Steve

ls1nova71

iTrader: (4)

First question I always ask when someone's cruise doesn't work, do you have LED taillights?

supershift67

iTrader: (1)

Do you have 12v power to pins 46 and 32 at the TAC module or maybe ecu on the trailblazer
then momentary 12 volts to pin 49
then momentary 12v to pin 28.
vss signals to 44 and 45.
Not sure if this helps at all. this is from the wiring diagram for a 2006 6 4.2 trailblazer. Either way good luck and hope you can figure it out.

slosteve

I have a small 3rd brakelight that's LED and disconnected it during my search for solutions; it had no effect.

Steve

ls1nova71

iTrader: (4)

Ok, so you do have regular light bulbs for brake lights? (1157 or something similar?) What are you using for a brake light switch? Have you verified that you are definitely getting the 12v to the cruise wires?

slosteve

12v at #46 and 0v at #32 until brake is applied; then it's the opposite.
constant 12v at #49 (on/off switch)
12v momentary to #28 & #11 respectively (set & resume switches)
Did not check vss signals; are they 12vlt?

Steve

slosteve

Yes, 1157 bulbs. I am using the stock '54 for the brake lights and recently installed a late model combination brake/cruise switch seperatly just for the cruise cancel. Yes, am getting 12v at the C1 connector to the PCM.

Steve

supershift67

iTrader: (1)

the vss wires come from the speed sensor and would probably be an a/c signal. No dc voltage. You would probably have codes for this in the ecu as maybe a p0500 code. Do you have a TAC module like a little black box or is it all coming from one controller?

Dave_62

iTrader: (10)

Not sure if yours is the same, but on my 2004 LQ4 with DBW swap the cruise wouldn't work either. Digging through the factory manual I found that it needed a "I'm OK" serial data signal from the antilock brake module for the cruise to function. Since the swap recipient didn't have antilock, cruise was a no-go.

supershift67

iTrader: (1)

pin 44 and 45 are coming from the vss signal which should be on the transmission. What transmission do you have. The sensor on a 4x4 is on the transfer case. If you are running a non overdrive like a th350 or 400 you would have had to add a vss for the speed control.

supershift67

iTrader: (1)

If that is the case then there is a serial wire coming from the instrument cluster I believe. I am not sure how to get around this. It may be able to be programmed out and let the speed control work but I am not sure on this.

slosteve

No TAC module, just the PCM. No Codes either! I have a Dakota Digital instument panel and the speedo & tach both work fine using the outputs off the PCM

Steve

slosteve

I saw the class 2 serial data wire from the inst. cluster - my 'puter flasher didn't think it was necessary.
I'm using the 4L60E that came with the engine.

ls1nova71

iTrader: (4)

What does "seperatly just for the cruise cancel" mean? Do you have another switch for your brake lights? The cruise needs to see a ground through the brake light circuit at start up for the cruise to function.

ls1nova71

iTrader: (4)

There isn't anything the abs has to do with cruise in a swap. As long as its wired correctly it will work . I have wired cruise on every DBW swap I've done and they have all worked flawlessly. The "I'm OK" As you put it is through the brake light circuit, and as long as it checks out on first start up everything will work as it should.

ls1nova71

iTrader: (4)

That serial data wire isn't coming from the cluster as much as going to it. It runs the guages, PRNDL, ect. Its not necessary.

slosteve

Hmmm......Okay, here is what I did. I was using the original '54 brake light sw. for the lights & cancel. Then I discovered the 'cruise release' circuit and decided to install a new 'dual' switch in another location. Not wanting to re-do the other brake light wiring I just ran another circuit from constant hot to the open side of the switch and then to the pin #32 'cruise cancel'.

ls1nova71

iTrader: (4)

32 should be hot when the brakes are applied, this should be tapped into your original switch. Then use the normally closed set of contacts on the cruise switch to hook to power on one side and 46 on the other. I think that's right, but I left my schematic I had at work last night. You may be better off using one switch since they need to open and close at almost the exact time. If the PCM sees the brakes applied but the cruise switch isn't open it could default to not working.

slosteve

I'm on it. Thanks and I'll let you know the results.

Steve

slosteve

You sir, are the man of the day!

My cruise finally works!!! I wired the brake lights into my new switch; still had problems - the brake lights would come on when they weren't supposed to, go off when they were supposed to be on, yada yada yada. So I took the switch out and checked it and it worked fine(!?). So I put it back together and disconnected the LED third brake light and it worked fine. So I took it for a test drive and WALLAH, the cruise worked perfectly. Thank you very much for your excellent input.

Steve