hi i have my dads van he wants to pass smog in Ca 95 Pontiac transport 3.8 with 145k
i scaned 3 codes p0122 tp sensor low,p1406 egr pintle position and p1640 qdm 1 failure with Snapon solas i removed egr check for blockage and cleaned tubes and intakes with carb clean. it seams that code for p1640 hard codes most times soon as it runs, not all the time but most, some times 10 20 miles,
other codes have not come back yet.

one drive issue is for last couple years trannys first to second shift seams late 2800 rpm under light foot unless you lift foot for split second than shifts fine and all other gear changes and lock up seam fine and smooth

Is code p1640 part of tranny shift solinoid issue on 4 speed trans?,any one know tree flow for code p1640? i know Qdm 1 controls different things on different models it would help us great deal know what to do? thanks jason

tps, egr and trans share common power from computer BE5. test for voltage and trace wires sounds like something is shorting it out.

thanks will try and post back