What hurdles will I face in replacing the 3 speed auto with an overdrive trans in a 1992 D150 (3.9L)? Does the standard wiring harness work in each case? What about the control module? Anyone with experience with this swap?

 

Depends on if your truck originally had an O/D trans, judging by your other post..... I would almost think so.

The O/D trans is going to be longer though, so, you will need to swap the driveshaft as well. If your truck DIDN'T originally have an O/D trans, and just has a confused PCM, then the PCM, and wiring will also need to be installed.

 

From what I have read I'm not certain 92 offered a true overdrive transmission (4 or 5 speed). I'm totally unfamiliar with lockout torque converters but one site described it as a type of overdrive. The maintenance light has been on perpetually the entire time I've owned the truck and the code is "Overdrive Transmission Solenoid". Since it is clearly a 3 speed I assumed it was an error. When I read a little about the locking converters I put 2 and 2 together and thought perhaps the truck has a locking converter and that solenoid is bad and the PCM might be programmed to report that as an OT problem.

 

Well, apparently, they were available with the 4spd auto...... Might want to run your vin, and get a build sheet, and see what it originally came with. (go here, click on 'equipment listing', then enter your vin on the page that pops up.) Posting pic of your current trans would help too.....

 

If you have a OD trans you will have a switch on the dash to turn the OD off/on. The OD trans A500/A518 was an option first appearing in 89. Not sure if it stayed an option until 93(first year for the magnum). Your "maintenance" light is not any kind of code it is a reminder to take it to the dealer for "maintenance". The light will come on after a certain amount of run time accrues. If you have a code/s your check engine light will come on. You can check the codes here...
http://www.allpar.com/fix/80s-codes.html

 

I definitely do NOT have a OD trans. The info on the MOPAR site said that it is a 32RH three speed trans with a lockout torque converter. However, the label underneath the hood identifies it as an A998. At any rate, there is only 1,2 and D on the gear selector (plus P,R & N) and there is no OD switch on the dash. According to every auto parts web site there are two OD solenoids available for this trans, a two-wire single solenoid and a three-wire double solenoid. I dropped the pan and there is a one-wire single solenoid above the valve body. No one lists a single wire solenoid for this trans. The code clearly states Overdrive Transmission Solenoid and there is only one solenoid in the trans. I found a part number 68212881AA one wire solenoid and I am going to go for it. I'll post the results later.

 

You want the TCC solenoid, not the O/D solenoid. Your three speed doesn't have O/D, so, it doesn't have an O/D solenoid.

 

I replaced the torque converter lockout solenoid but can't tell if it is working now. The Haynes says that it won't reset the check engine light until after 50 startups. That's crap. Any pointers on how to tell if the lockout feature is working now?

 

Do you have a tach? TCC engage should drop rpm about 200 or so.

 

No tach. I'm looking for a code reader for this model that can reset the codes.