I have an idea. I know that some ECM/PCM programming systems let techs turn on or off settings for diagnostics, I have seen this done on forums for other makes/models. The problem is finding a cooperative tech at a dealership willing to give it a shot.
The problem seems to boil down to this:
Since the MPH & RPM don't match the ECM thinks the clutch is slipping and disengages the cruise control.
There are two possible ECM fixes:
1) Change the ECM MPH/RPM table to match the SL1/MP2 value for 5th.
2) Disable the "clutch slip disengage" logic entirely.
If there was an option for a tech to disable the clutch slip action that would work, other than the clutch cruise cutoff but you have the fix for that here.
The "elephant-in-the-room" is exactly what can or can't be done with the flash programming. I may be able to get an answer. I just happen to know a service tech who is now working at a Saturn dealer. I'm going to talk to him and get him to find out how much he can do with the ECM flash programming on an SL. If he can change either the 5th ratio in the programming or disable the clutch-slip-cutoff then we will have the specifics to be able to go to a dealer and say "re-flash mine with XXX changes", pay their fee (should be reasonable), and have this whole problem solved. This may take a few weeks to find out, so check back.
Wait one dang minute, are you telling me that there is a seperate module for the cruise? And I just need to fake out that light blue wire?!? Dang, why didn't you say so sooner
history, since my trans swap, the gear ratios in the transmission do not match what the computer is expecting, so the cruise control thinks the clutch is slipping and it won't engage. Saturns have some peculiarities to them, But I still like 'em
You might check and see if the DOHC uses the exact same p/n cruise control module as the SOHC. If not, maybe you could get an SOHC one at a junk yard.
i threw out my automatic and installed a manual trans out of a dohc car ( i have a sohc) my cruise still works.
yes, these cars are cruise ready. there are instructions on www.saturnseries.net
all pcms have the capability to do this.
this may be different for late 99-01 s series cars as those have a bcm.
Resurrecting a long quiet post, sorry, haven't been on here since... 2008! A lot has happened over those years, but my SL2 is still going strong with 252,000+ miles now. I've worked at home for the past two years so mileage concerns went out the window.
SL info and parts have become more scarce, still haven't been able to confirm if the 99-02 SLs have a separate cruise module or not. I think they don't, pretty certain that it is all in the PCM/BCM so would require someone with the factory service computer to flash. I haven't been to Pull-A-Part in a while, but want to go soon. I'm going to try to find a 2000-2002 SL1 manual with cruise to get one from... wish me luck.