Cruise control explanation - '03 manual vs. automatic equipment

Hurley

Hurley

BLAKLUNG
Joined
Apr 27, 2008
Messages
3,698
Ok, I've been trying to diagnose off and on for nearly a year now why my manual-to-auto swapped 03 does not have cruise control (manual VB, no PCM). I've read the speed control section of the 03 FSM, but have basically only learned that:

- diesel equipped with manual trans has an all-electronic cruise control via ECM
- diesel equipped with auto trans has the vacuum pump, servo, solenoid, etc. system controlled by the PCM.

It appears to me, then, that if I have a modified ECM file from Smarty that makes my truck 'think' its an auto, there is no way the cruise will operate since the ECM would be looking for a nonexistent PCM to control the vacuum servo. Is this correct? Or is there some knowledge from Smarty that I am missing?


Aside from my confusion above, what I've done so far to diagnose not having cruise:
- the cruise light illuminates on the gauge cluster when I hit the switch.
- verified that the brake light switch is good.
- confirmed VIN# on Smarty matches truck VIN.
 
Yes, I bought a modified recovery file from Smarty. I had conversed with Brian @ Smarty about what could be up, and covered all of the variables he has asked about.

I may not be asking the right questions, too. All I know is that it runs, has no start-assist (which I asked for after ditching the manual), and unfortunately no cruise.
 
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I'd say it's the tune, I didn't change tunes after I swapped and everything works fine.
How'd you wire your clutch switch? Curious as to what you're calling start assist to?
 
Clutch switch is wired back to NSS on the auto trans, truck only starts in P or N.

Start assist = the feature that makes the truck maintain rpm when you let the clutch out without depressing the throttle pedal.
 
I see, might just throw a jumper in the clutch switch plug under the dash to troubleshoot. If it sees the clutch is depressed any at all cruise kicks out or won't engage.

Never heard of the start assist before. It does explain why my truck tried to take off like a bat out of he11 at idle sometimes :lolly:
 
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