90 GMC 5.7liter motor.Transmission will sometimes when put in drive not engage.If I wait a few minutes,it will engage and works fine after that.Mostly does this when outside temps are cold (28 to 40 degrees).Makes no noise and does not slip.This is a 4x4 truck.

No reverse on this model almost always means a cracked cage in the transmission.Good news is you just have to have the cage changed and not much else and all should be fine and won't cost too much.

Sorry to tell you this. You have an AXOD/AX4N Transmission and it is going bad on you. Soon, it is going to strand you on the road.

This Transmission is a Money Maker for the Mechanics and Transmission shops around the world.

Some people will put Lucas into their transmissions to extend the life of the Transmission but there are people who do that and cause it do DIE!!!! and I mean Immediately.

I am sorry to give you the bad news but at least it is Honest...
P

Sounds like the pump is going bad inside the transmission.

You could also have a leaking seal when the transmission heats up enough to expand and leak. That or if the electronics controlling the transmission are getting excessive resistance do to a short, that could also cause the problems you are describing.

There is an acuator in the front diff the are common to quite in late 80 to early 90 Chevrolet's / GMC

Replace the speed sensor in the transmission this issue has caused rear differential damage on vehicles I have heard of, also check the under neath electrical connections that go to the transfer case to ensure no damage to the wiring harness or electrical plugs has occured

Its the electronic shift control located just under the battery ontop the transmission replace or repair will solve the issue

it'll go into drive but once it reaches 1500 rpm it'll drop into neutral as a safety because at this rpm it is being told to shift gear and when it fails to do so it safely goes into neutral

it will go into reverse just fine and park and you can run all the low drive gears until you reach 1500 rpm then it'll cut it off

i pulled mine out re soldered bad components on the board to fix it but im an electronics engineer it may be easier for you to just replace it

could be your front actuator or your actuator motor on the transfer case.

This is called limp mode chrysler did this to protect the transmission without leaving the owner stranded by the road,a few things will cause this mainly putting the wrong fluid in the transmission,they use only atf+4,or the govenor pressure sensor is acting up which should cause a check engine light to come on,or the transmission just needs a fluid and filter change,should be done every 2yrs or 36k miles,due the fluid and filter change about 40.00 but if you have the wrong fluid then the whole system needs to be flushed and refilled-transmission-torque convertor,radiator and cooler if equipped and all lines.

what is the (revolutions per minute) rpm of your engine when the torque converter engages, was the torque converter rebuilt too? what type torque converter is in the ford ie low stall where it engages the gear box at around 900 to 1000 rpm. has there been any power band adjustment by the company that rebuilt your automatic transmission after the insallation.

The anti-drain-back valve in your torque converter has gone bad. The torque converter drains into the tranny when you shut down, and you have to wait until the pump refills it before it can work.

The pump does NOT fill the converter in park, only in one of the gear positions, or neutral. Start it up in NEUTRAL, wait a minute, and drive off.