scooter08

I know this is a common swap to do but im running into some issues because of the way im trying to do it. Ive got a 1986 toyota pickup and im putting in a 2003 4.3 vortec. the only issue im running into is the wiring harness, the reason this is a n issue is because im using a newer engine and a manual transmission. i have called painless performance and they only go to 99 vortec. Howell doesnt make a complete wiring harness. so i was wondering if a s10 manual vortec harness would work as a last resort or if there are any ideas out there. just trying to find a wiring harness thats not for an auto transmission and a 2003 vortec is the biggest issue. thanks

Hadmatt54

Did the 4.3 come out of a manual to start with? Are you trying to mate it to a yota or a GM tranny? the 86 yota manual only needs 4wd light and the back up light switch wired up. The 4wd switch completes the circuit to ground, the backup switch light is in and out to the backup lights. If you are trying to use a GM manual...I can't help you. If you have the engine, the engine harness and the proper ecu to run it, then the only wiring that you have to do is start circuit, charge circuit, check engine light, temp, oil gauge, probably speed sensor, ect. If you are looking for someone to tell you to connect the red wire to the blue wire on connector AB6, that's not going to happen. You need a wiring diagram manual for your 86 and you need the wiring diagrams for the vehicle that the 2003 4.3 came out of and figure out the circuits that need to be connected to make the two harnesses work with one another. I don't know when GM started adding immobilizer circuits, but if 2003 4.3 had a immobilizer circuit, you are into a whole bunch of new problems

scooter08

the 4.3 came out of an automatic blazer without a wiring harness. im trying to find a new engine harness to complete the conversion. its the chevy 4.3 to the toyota manual transmission. I guess i just need to know if anyone makes a custom wiring harness or if a manual s10 wiring harness would work on the auto blazer engine to complete the project. I almost forgot, what would be a good radiator for the conversion as well?

Hadmatt54

Unless you find someone who has done exactly the same swap that you are trying to do, you will not get specific questions answered.
If the 4.3 had a separate transmission computer for the auto then having a transmission harness might be a mute point. If the GM computer controlled the Engine and the transmission, then you will probably have a problem with it throwing transmission codes once you get it up and running.
If this is the first swap that you have tried, it will indeed be a learning experience. there will be walls that you will have to find a way around.
My son and I just finished an off road truck last week. we built it in 4 weeks and were wheeling it last Saturday.
1986 short box reg cab pickup frame with a SAS done 8-9 years ago.
1994 reg cab
1989 extended cab pickup doors,fenders and hood.
1989 extended cab wiring harness from a 3.0l 5 speed
1999 Tacoma 3.4l v-6
1986-87 turbo 5 speed R151f manual transmission with a 23 spline transfer case.
Mid 90's landcruiser electric locker high pinion front differential.

My son did most of the fab work, I did all of the wiring. There are lots of articles for a 3.0 to 3.4 swap, but I found none for the 89. First I bought an 89 wiring diagram manual off of ebay, then I downloaded the wiring diagrams for a 97,98 and 99 Tacoma from the Toyota site ($15.00 for 48 hours.Oh and the Toyota site only goes back as far as 1990, so that won't be of any help to you!)
Piece of cake...right?...Wrong!!!
The 99 Tacoma Engine wiring to cab harness plug did not match the 99 diagrams. Not only was the connector different, but the pin configuration was different as well. Turns out the connector on our 99 harness matched one of the connectors on a 97 harness, but the pin configuration wasn't the same, so I had to trace every wire in the engine connector as well as connector E5 of the ECU to identify the circuits. Once that was done I drew up a connector and pin configuration diagram and then drew the connections to the 89 pickup harness. This alone took me at least 5 to 10 hours of work and this was even before I started connecting a single wire.
I'm pretty longwinded here, but my point is that wiring an engine swap can be very frustrating and there will always be roadblocks that you will have to work around.

scooter08

So do you know anyone who has an Engine harness to start with since i dont have one?

Hadmatt54

If you were going all Toyota I might be able to help in that respect, but since you are going GM...I'm afraid I can't be much help.

scooter08

ok thank you!

donomite49

i think you will need a wiring harness for the 4.3 and ecu from a manual trans application.
then get your ewd's (electrical wiring diagrams).

click on the offroad tech and fab link on the homepage, and you'll see the engine swap section. there is a section for 4.3 swaps.

search and ye shall find...

yotatech rocks!

yota864x4

Try searching around junkyards and craigslist. You have to be able to find something. Then do research here and read as much as you can, when you're done read some more. Then get out there and do it, that's the only way to really learn and get it done. Oh and another thing, please soder and shrink tube all the connections. If you scotch lock or crimp connect you'll end up having to redo it later on.

Pat8942

Too bad you didn't go with the TBI 4.3, it would have made it much easier wiring wise.

Turd Furgeson

We have sold people the 3-row copper brass toyota radiator for small block chevys and fords that have worked. Those were bone stock,or very mild small blocks though. And the bottom hose on the toyota rad will probably need one of those rubber adapters since the chevy hose is probably bigger (not familiar with that new of 4.3). We've seen the cheap copper/brass rad cool said small blocks with a 16'' spal electric fan mounted to the rad,and we've also seen engine driven flex fans with a properly built/fabbed fan shroud work too. And it will bolt right up to your core support like a factory radiator.

clarion69374

Forget getting a harness for a 2003 4.3 with a manual trans because I'm almost positive they don't exist. You need to pull the vin for the motor you have and have a pick n pull yard cross reference for you to find an ECM and harness as a complete unit. The motor will run fine without the auto trans you will just need to have a custom tune done to delete whatever you aren't using in the swap.

Mitchell12

Good just go after market engine management? Complete standalone.

skypilot

iTrader: (1)

well.......

Go to your local pick & pull and find that engine in that truck. Take the engine harness and as much of the chassis harness as you can along with the ECU. More is better, and make damn sure you get every single sensor!

Now what you do is hot wire the engine / ecu by finding B+ into the engine harness and connect all grounds. Hot wire the starter. Check fuel, & spark till you get ignition. Move from there. Oh and you need a HP pump for the injectors!

Lot of work ahead of you.

I put a 1992 3.slo into an '88, not easy.

scooter08

thanks for the info, i have already been calling the pull yards and looking for radiators.