Hi all, So I have me a new van with an issue, I cant get 4th out of it.
I know there are a few problems that can casue this. Things I can check on and build to test.
When I got the van it would not warm up and was throwning a code 17 Closed loop temp not reached or engine cold too long.
Replaced thermostat and she warms up ok now. Still no 4th so that was not it.

I would like to get a pigtail and built a switch box to plug into the three pin connector to manually test the functions.
I read somewhere that the center pin was 12v and the system grounds each of the other two pins to engage 4th and trip the converter clutch. If anyone has more specific info on that I would love to hear from you.

The O/D disable switch on the dash light does light up when I press it, and turns off when I press it as well, tho there is no change in RPM and I dont feel any shift. Tested at 90kph with cruise control on flat ground.

Since this van is 33 years old she may have had other work, I have also read that the ECU controls 4th and lockup, since these vans with the 5.2L some had 3sp and some 4sp it tracks that there would be different computers, I wonder if somewhere along the line someone changed computers and she has the wrong one. How would I check for that?

Is there a relay or other control outside the transmission I should look at before I drop the pan and start looking at the lockout solenoid?

Thanx!

 

Get the part number off the current PCM, and then do a google search on that number. Somewhere should tell ya what trans is was for.

 

well I found I have a 4379889 ECM but no where I can find shows it as either 3sp or 4sp

I am starting to think the ECM may not control the 4rth lockout solenoid.
Perhaps it is only controlled by the dash switch? Tho I just looked into it and there does exist an ECU code 45 Transmission OD solenoid circuit short or open condition detected
since this code exists the solenoid must be ECU controlled...

 

The O/D off button just sends a signal to the PCM, and the PCM interprets it. The button has no direct connection to the trans.

The number says it should control the 4spd trans...... Kinda curious why yours is not.

 

Your the second person to tell me that number is for the four speed.
My working theory now is that my kick down linkage is adjusted wrong, the way it is now, there is no throttle movement without moving the kickdown, so I think even at idle its in a kickdown state.

Trying to find the correct way to adjust this.

 

It's possible someone did the 3sp to 4sp tranny swap at some point in the past, it's can be done on models up to 1995. It's also possible they tried unsuccessfully to swap in a 4sp ECU and failed so they the did the shortcut version and just went ahead and installed a switch to operate it manually.

https://transmissioncenter.net/shop/...p-information/

 

You adjust the kickdown linkage (engine off) with the springs in place, block the throttle wide open, loosen the adjusting bolt down on the tranny, make sure the linkage rod stays forward where the springs are holding it while you move the kickdown lever all the way to the back, hold it there and then tighten the adjusting bolt. Remember to unblock the throttle before starting the engine.

 

Thank you so much for this proceedure!!
I will test this the next time I get a chance to do so!

 

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