Here is one tip found in Mitchell's website.
Malfunction indicator lamp (MIL) on, trans stuck in 2nd or 3rd gear, instrument cluster inoperative (diagnose & replace ignition switch if necc). See bulletin #01-07-30-002. Techs in field report IGN switch failure is common & may cause multiple symptoms with trans, IPC or other IGN feed circuits. (DTCs) P0740, P0753, P0758, P0785, P1860 may be set.
Most likely cause of this condition may be a loss of power to the transmission on circuit 1020.
To verify, with the ignition switch in the run position, test for battery voltage at the appropriate fuse listed below.
1997 s/t trans 24
1998-2003 s/t (old style) cluster 11
2002-2003 s/t (new style) ignition 0
1997-2000 c/k (old style) trans 20
1999-2003 c/k (new style) ignition 0
1997-2002 g-van trans 20
2003 g, h-van ignition 0
2003 H2 ignition 0
After IGN switch replacement, VTD (theft deterrent) relearn must be performed.
***If you have aftermarket alarm or remote starter, I recommend removing them temporarily.***
I am sending you the complete P0785 diagnostic. Did you happen to check the wiring to the transmission?
Saturday, June 6th, 2009 AT 11:49 PM