thanks. it makes sense of a dirty connector with it only giving me issues when its raining. I'm about to crawl under and see. thanks

my '95 G30 had a bad alternator at one time and when the battery got too low the trans would slip into 'limp mode'...

that's something else to check - when i would hit a puddle my alternator used to scream and the volts gauge would drop...

i eventually put in a new alternator and battery...

never had another problem until my battery hold down broke during a panic stop - the battery flew forward and shorted out and blew 'something' in the trans electrical - i also had to drive 40 something miles home in first gear... that was fun...!!!!!

that is a possibility. First time it gave me trouble I had wipers, cruise, and the radio on. and it fell out of 4th. but came back when i turned the wipers and cruise off. hmmm.

the connector at the transmission was fine. still snug and clean. there was a trace of fluid around the gasket and the rear seal. So I am thinking low fluid made it do this.

Check and clean your ground cables. I add a couple of small ground straps on most of my vehicles just to keep down trouble.

They also occasionally have problems with the wiring harness inside the tranny, they are available aftermarket, I know rockauto has them.

Like Catfish says check the grounds, but also the Battery and alternator.....sometimes the alternators on the way out fluctuate the voltage and drives the puter crazy and affecting everything electrical...Next time it won't shift out of first check the voltage at the battery and leave everything on.....

I came across this on AllData; i don't think it's your problem - but it may be good to post here for someone who also has a problem with their trans:

TECHNICAL

Bulletin No.: 08-07-30-027

Date: June 04, 2008

Subject:
No Movement When Transmission is Shifted to Drive or Third - Normal Operation When Shifted to Second, First or Reverse (Replace Forward Sprag Assembly)
Models:
1982 - 2005 GM Passenger Cars and Light Duty Trucks
2006 - 2007 Buick Rainier
2006 Cadillac Escalade, Escalade ESV, Escalade EXT
2006 Chevrolet SSR
2006 - 2008 Chevrolet Avalanche, Colorado, Express, Silverado Classic, Silverado, Suburban, Tahoe, TrailBlazer
2006 GMC Yukon Denali, Yukon Denali XL
2006 - 2008 GMC Canyon, Envoy, Savana, Sierra Classic, Sierra, Yukon, Yukon XL
2006 Pontiac GTO
2006 - 2007 HUMMER H2
2006 - 2008 HUMMER H3
2006 - 2008 Saab 9-7X
with 4L60, 4L60E, 4L65E or 4L70E Automatic Transmission (RPOs MD8, M30, M32, M33 or M70)

Condition

Some customers may comment that the vehicle has no movement when the transmission is shifted to DRIVE or THIRD position, but there is normal operation when it is shifted to SECOND, FIRST or REVERSE position.

Cause

This condition may be caused by a damaged forward sprag assembly (642).

Correction

When inspecting the sprag, it is important to test the sprag for proper operation by holding the outer race (644) with one hand while rotating the input sun gear (640) with the other hand. The sun gear should rotate only in the counterclockwise direction with the input sun gear facing upward. If the sprag rotates in both directions or will not rotate in either direction, the sprag elements should be inspected by removing one of the sprag assembly retaining rings (643). Refer to SI Unit Repair section for forward clutch sprag disassembly procedures.

If the sprag is found to be damaged, make repairs to the transmission as necessary. A new forward roller clutch sprag assembly is now available from GMSPO.




If clutch debris is found, it is also very important to inspect the Pressure Control (PC) solenoid valve (377) fluid screens. Clean or replace the PC solenoid (377) as necessary. It is also important to flush and flow check the transmission oil cooler using J45096. Refer to SI Automatic Transmission Oil Cooler Flushing and Flow Test for the procedure.




The notches above each sprag must point up as shown when assembled into the outer race.

Bearing Assembly, Input Sun Gear

Snap Ring, Overrun Clutch Hub Retaining

Hub, Overrun Clutch

Wear Plate, Sprag Assembly

Retainer and Race Assembly, Sprag

Forward Sprag Assembly

Retainer Rings, Sprag Assembly

Outer Race, Forward Clutch

Washer, Thrust (Input Carrier to Race)

The following information applies when this sprag is used in 1982-86 transmissions.

The new design sprag can be used on models 1982 through 1986, by replacing the entire assembly (637 - 644). Individual components are NOT interchangeable.

Important: The wear plate (640) and input thrust washer (660) are not required with the new sprag. Use of the thrust washer and wear plate with the new sprag assembly will cause a misbuild (correct end play cannot be obtained).



...more coming

Like stated above, it definitely sounds more electrical than mechanical - something about putting electronics in control of mechanical; if it turns out that your electrical system is in fact good, i think this might be another problem: it's basically the 2-3 shift solenoid inside the trans.


INFORMATION

Bulletin No.: 01-07-30-036H

Date: January 29, 2009

Subject:
Diagnostic Tips for Automatic Transmission DTC P0756, Second, Third, Fourth Gear Start
Models:
2009 and Prior GM Passenger Cars and Light Duty Trucks
2009 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X
with 4L60-E, 4L65-E or 4L70E Automatic Transmission (RPOs M30, M32 or M70)

Supercede:

This bulletin is being revised to add the 2009 model year and add details regarding spacer plates. Please discard Corporate Bulletin Number 01-07-30-036G (Section 07 - Transmission/Transaxle).

Some dealership technicians may have difficulty diagnosing DTC P0756, 2-3 Shift Valve Performance on 4L60-E, 4L65-E or 4L70E automatic transmissions. As detailed in the Service Manual, when the PCM detects a 4-3-3-4 shift pattern, DTC P0756 will set. Some customers may also describe a condition of a second, third or fourth gear start that may have the same causes but has not set this DTC yet. Below are some tips when diagnosing this DTC:

^ This is a performance code. This means that a mechanical malfunction exists.
^ This code is not set by electrical issues such as a damaged wiring harness or poor electrical connections. Electrical problems would cause a DTC P0758, P0787 or P0788 to set.
^ The most likely cause is chips/debris plugging the filtered AFL oil at orifice # 29 on the top of the spacer plate (48). This is a very small hole and is easily plugged by a small amount of debris. It is important to remove the spacer plate and inspect orifice # 29 and the immediate area for the presence of chips/debris. Also, the transmission case passage directly above this orifice and the valve body passage directly below should be inspected and cleaned of any chips/debris. For 2003 and newer vehicles the spacer plate should be replaced. The service replacement spacer plate is a bonded style with gaskets and solenoid filter screens bonded to the spacer plate. These screens can help to prevent plugging of orifice # 29 caused by small debris or chips.
^ This code could be set if the 2-3 shift valve (368) were stuck or hung-up in its bore. Inspect the 2-3 shift valve (368) and the 2-3 shuttle valve (369) for free movement or damage and clean the valves, the bore and the valve body passages.
^ This code could be set by a 2-3 shift solenoid (367b) if it were cracked, broken or leaking. Refer to Shift Solenoid Leak Test in the appropriate Service Manual for the leak test procedure. Based on parts return findings, a damaged or leaking shift solenoid is the least likely cause of this condition. Simply replacing a shift solenoid will not correct this condition unless the solenoid has been found to be cracked, broken or leaking.
It is important to also refer to the appropriate Service Manual or Service Information (SI) for further possible causes of this condition.

if i were in your shoes, i would take the van to an Autozone, Advance Auto Parts, or Pep Boys and have them do a charging system test, then a battery test...

from there, they could tell you if there's something weak (maybe the alternator's on it's way out and not giving min. 12.6V at load) or, maybe there's a fault in the alternator feed line...

next, i would check all the fuses and make sure they're correct...

you can check here for any history fault codes, it is OBD1 (pre-1996): http://www.troublecodes.net/GM/

you could also check your belt tension, and the wiring going into/out of the computer (the computer's under the driver's seat)...

did you drive the van any more last night...?

I am gonna drive it to Auto Zone and have it checked out. thanks. I really feel it's electrical too