I have a 2000 QC 4.7L auto that has done the same thing to me. Since
installing the thermostat and Jet Stage II chip the MIL (check engine light)
come on regularly (I usually reset it becuase it only goes on shortly after
starting the engine). It only seems to do it on hot days also.
I wonder if the IAT sensor integrates with the thermostat inside the PCM
somehow to rat on me for having the Stage II and thermostat, even though the
thermostat should not really have anything to do with it since the
thermostat doesn't even kick in until ~180 degrees.
The MIL will also trip without the Stage II chip installed, so I'm thrown
for a loop.
The only reason I haven't taken it to the dealer yet is that the MIL doesn't
irritate me that bad, and it's a good conversation starter. ;)
Adam
"Paul Macey" <pmacey@ans.net> wrote in message
news:Pine.GSO.4.05.10107311510350.27230-100000@paul.ny.ans.net...
> Subject line says it all. Yellow Check engine symbol came on upon startup
> last night after my truck sat in the hot parking lot at work, all day.
>
> Service dept reset the code on my 2001 4.7, said all should be fine but
> scheduled a tentative appt for 8/20 to check into it further (they allowed
> me to stop by today with no appt to check the code and clear it)
>
> I have a Robert Shaw GT755-180 t-stat and Jet Chip II that have been
> installed for at least a month. The temp gauge has and currently is, at
> the same reading since these installs, the truck's performance remains the
> same.
>
> The t-stat appears to be functioning normal, during startup, it runs
> smooth, same idle as always, and warms up to operating temp as it always
> has before...looks like it is not stuck open or remaining closed, right?
>
> Thoughts on my next step? Just drive the truck till 8/20 to see if the
> check engine light comes on again? Go under the covers and check the
> t-stat? Bring it for service w/o the Jet Chip and let them pull the t-stat
> and possibly charge me for that service? Allow them to re-install the
> stock 190 t-stat that I kept? Replace the 180 t-stat (are these GT755-180s
> bullet proof?). Call Jet Chip and describe the problem and ask for a new
> chip? Reset the PCM (I know this would have cleared the original code)
>
> I hate to have the service dept or me go under the covers if it can be
> avoided at all but I also don't want to cause any potential problems with
> the engine...just a quirk in the PCM code or temporary problem with the
> t-stat/chip?
>
> Anyone else have the same code and symptoms? If so, what was your final
> fix?
>
> Thanks in advance!
>
>
>
>
>
>
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:02:15 EDT