1998 Pontiac Trans Sport
3.4L
dash lights = No
codes = None
work done prior = Changed the transmission fluid & filter several years
ago
work done to repair = Added Lucas transmission treatment
tech = SF
question = The transmission sometimes comes out of gear while stopped
at a traffic light or stop sign. It is very random. It may not happen
for several days or weeks and sometimes it can happen twice in one day.
When the problem occurs, it sometimes takes a minute or two of shifting
back and forth from Drive to Park to Drive before it starts going
again.
The transmission never slips or comes out of gear while the van is
moving. It only seems to occur after the van stops at a stop sign or
traffic light.






SF:
First, be sure to check fluid level and condition.
There is nothing external or electrical that can cause this.
May have a problem in the forward clutch, forward band apply, or a rolled  
seal.
In any of these cases, removal and disassembly would be needed. May be  
time for an overhaul.
You could try to have a trans. flush service done and see if it helps.
Other related articles:
2003 Pontiac Grand Prix
3.1 V6
Check Engine Light
codes =P0753
tech = JK
question = I have a 2003 Pontiac Grand Prix with 84,000 miles on it.  
My "Service Engine Soon" light just came on about a month ago and when
it did my cruise control stopped working as well.  I can feel it has
trouble shifting and I have hooked it up to a machine that AutoZone has to
check my problem and it says its a transmission module (P0753).  We
have asked others who say that it probably isn't the problem because they
have never heard of one of those going out and it's probably a wiring
issue.  Can you tell me what you think it might be?

SF:
This codes refers to the 1-2 shift solenoid. Be sure to check all fuses first. Specifically the
"TCC" fuse in the underhood fuse block.

If that is ok, 2 things possible. Either you have a connector problem at the 20-way  
transmission case connector causing this code, or the solenoid. The solenoid is on the  valve
body in the side case of the trans.
Suggest disconnecting transmission connector with key off, look at all terminal, pull the
harness a little so as to change its position, then plug it back in. Clear the codes and drive it.