03 4x4 conversion/build thread

Hello names Robert,

I've read a few other threads about doing the 4x4 conversion to 1st gen prerunners and my 03 Tacoma sr5 3.4 auto trans is going to be the next candidate. I will be doing all the work myself. Im actually a tech for Toyota but this is the first yota I have owned and I have never attempted a project such as this, but I should have all the necessary tools and even a lift to use. Any useful information you can provide me would be great.

The only question I have as of now is I have located a transmission and transfercase out of a 98 4runner for a good deal. Would this transmission be a good candidate for my truck? What modifications should I expect to have to do to this trans to make it work?

 

You would need to stick with a transmission for your year or maybe an 04. I believe they changed the A340F in 02. You have the drive-by-wire throttle body on your 03 so the transmission needs to be electronic.

IMPO. You should find an 03 truck to get the transmission, Full transmission wiring harness, Full engine wiring harness and the exact Ecu from the truck you intend to convert it to. I would stick with a j-shift unless you enjoy automotive electrical wiring. If you go with a push button you'll need the 4x4 ecu w/ connector and run a bit of wiring. Youll want an EWD for your year, and be able to solder wires and use automotive shrink tubing. Staying with an automatic makes your conversion substantially harder.

I do not recommend splicing wires with solder and never with butt connectors in the engine bay or under the truck. That's why I recommend full harnesses from a donor of your year. Also pins on the engine Ecu changed every year.

Good luck.

 

Oh, I forgot. I think 01-02 4runners A340F will work.

 

Okay Mr. Guitarist,

I will do the best I can to try and answer your question. I believe the automatic transmission used in the first generation Tacomas was called an A340. I could be wrong since I don't have any documentation in front of me, and I am definitely much more familiar with the standard transmissions because I have one. The 1998 4Runner I believe uses the same transmission as a first generation Tacoma. I don't think you need to do any modifications to the transmission to make it fit especially since it already has the transfer case. You are going to need to cut a hole next to the transmission controller in order to get access to the transfer case controller, but that is the only modification I can think of. The bolt pattern should be identical. You can make a template out of card board, and then mark the board where the transmission bolts are on your existing transmission, and then cross check the pattern with the 4Runner transmission. This will tell you if it will fit or not.

Good luck,
Paul

 

If that's the case License2Ill. Couldn't I just swap output shafts from the 98 4runner transmission into my current one.

 

I am going to send you some contact information.
You bring up a good point. The rear gear shaft on your Tacoma might be longer than the one in the 4Runner.
Paul

 

Output shafts have nothing to do with it. On your 03 a computer controls your throttle body AND transmission.

 

I didn't realize you had to mess with the electrical system. Is a new ECU and wiring harness neccesary? I could have sworn I've seen people do it completely without touching the electrical system (or minimally at best, not swapping the ECU).

 

on this forum there is a thread called FrenchTacos 2003 4wd Conversion. A lot of good info on that thread but his information does not match up with what your telling me License2Ill. Hes saying any 1st gen Taco or 3rd gen 4runner is compatible.

 

that's what I was thinking too bartmaster1234. The only thing ive seen besides the speed sensor wiring extension is if you are going ADD instead of manual locking hubs

 

You asked for advice. With the newer trucks it's not simple. With an electric transmission even more so.

Look over your 03 EWD.

 

Why not just by a 4x4 with the money that you spent on the prerunner and all the bs that you're going to have to get. Lot less headache, less questions, less bs period. You're a tech for Toyota I'm sure you would have the hook up on something. If nothing else at least some information for your questions.

 

Read thru frenchtacos build. He reused his tranny and used an TC adapter. He used a manual hub front diff without ADD, and a manual TC. He avoided most electrical components. He did a hack job on the TC wiring but if any of the solder rusts it's not that big an issue.

Regardless a 98 automatic won't work.

 

the price would be more aa northwest.

 

License2ill. He reused his tranny which required him swapping output shafts on his 2wd tranny with the 4wd output shaft. I was also planning on using a manual transfer case and manual locking hubs.

 

so basically I could still use the 98 tranny from the 4runners output shaft and extension housing to mount the transfer case in my truck

 

Anything is possible. But check out how the 98 has a kick down cable. Do you see one on your 03? Check out your harness connector on your 03. Now look at the one on your 98. See a difference?

 

Ah, I didn't read that fully. The 98 A340F output shafts and tc adapter should work with your 03 tranny.

 

yeah they do I just verified through my parts department the output shafts and extension housings are the exact same part numbers. Thanks License you've helped a bunch

 

I did see the 98s cable and was trying to figure how I would get it to downshift but that is too much trouble I don't want any part of haha