No Over Drive/ No 1-2nd Gear

So now I found out that when I place my van on Drive, it starts on 3rd gear. Also when I’m On the Highway, the O/D Over Drive does not work. When I shift into “L” Low, 1st gear works. I rebuild the Transmission Module and the Engine ECu. Same issue.

It does sound like the solenoids are not getting the messages TBH. Your stick selector is working but the electronics perhaps not so much. It shifts Ok when driving? Perhaps there's a hydraulic failsafe to change gears but the solenoids are not being driven.

If you can work out the wiring into the gearbox (it's only going to be 3-4 wires) you should be able to find the solenoid coils with a multimeter. Perhaps if you can wire some 12V LEDs onto the solenoid outputs of the gearbox ECU on a temporary basis (and hang then on the dash), then you can see if the ECU is attempting to shift. That will narrow down the problem.

Say the solenoids are 0.25A then you'll be looking for a resistance of 12/0.25 = 48 Ohms up to about 200 Ohms. If you find 3 or 4 of those you know they are intact, research the model of your gearbox to find the number of relays.

Looks like your gearbox is an Aislin same as mine, A340F is a rough code, a more exact one is on the side of the gearbox itself.

Also check for functional relays and fuses in the fusebox LHS under the console. Note that there is also a vehicle speed sensor that gets fed into the gearbox computer but if your speedo is working is probably Ok.

Hi Robert, I am experiencing the exact same thing! Did you end up fixing the problem?

First check you have enough fluid, and it's a reasonable (idealy pink) colour!
Only then, move on to other things!

Check while idling in neutral, with the long auto dipstick.