5-Speed Swap ECU/Harness Issue

[NEKExplorer]

I have almost finished an engine and transmission swap from a '99 3.4 5-speed 4x4 into my '98 Limited. I have swapped over both the engine harness and the ECU from the '99 as well.

What appears to be a significant problem to me is- there are 4 ports for harness plugins on the manual ECU but only 3 wires from the engine harness plug into the ECU. The 4th plug was NOT part of the engine wire harness and remains in the donor vehicle.

My '98 Limited DOES NOT have a similar plug for the harness just hanging out like the '99 did. I have any empty slot on the ECU

I have removed the dash from the donor vehicle and partially tracked tracked the wires from that plug and I suspect that some of them go out through the firewall into the engine bay behind the glove compartment, and the rest of the seem to lead at least as far as the instrument panel,

Anyway, does anybody have any idea how big of a problem this empty plug port is going to be? Is my rig even going to start? What do you think is going to work/not work?

Thanks

 

[RandyBobandy]

That plug is where the dash harness connects to the ecu, it contains important connections like your starter circuit and is definitely necessary. You will need to find the dash harness plug on your 98 and depin it, then put those pins in the correct spots in a plug that fits your manual ecu

 

[NEKExplorer]

Thanks- I have looked and looked for the plug but I just don't see it. I do have the original plug from the donor and I am trying to track all the wires back and hopefully transfer it over if I can.

 

[RandyBobandy]

The wire colors are unlikely to match up so I wouldn’t go by that alone, that dash harness runs throughout the entire vehicle and is a major pain to remove including a full dash removal and depinning the fuse box so it’s much easier to find that plug in the 98 and transfer the pins to your new plug.

 

[St Runner]

The limited has a 5 plug ecu and the SR5 and manual only have 4. If I remember correctly most of that 5th plug is for transmission and transfer case. As RandyBobandy said you need to get that fourth plug off the donor vehicle and then get wiring diagrams for both years and figure out which wires the 99 ecu needs. It does not need all of them because a lot of them were for the auto transmission. The dash harness lead that goes into the ecu should be over by the windshield pillar on the passenger side. It might not be the same plug but it will have the wires you need

 

[NEKExplorer]

Looking at the wiring harness on the 98 limited, it looks like all of the plugs on the engine wire harness go into either ECU or the port with the lever-lock that is not part of the ECU. The '98 limited does not seem to have an equivalent of the the 4th "dash harness" plug on the chassis of the '99 SR5.


I'm kinda stumped and probably screwed.

Plug 'n play they said, just take the harness and ecu from the donor they said, lol.

Thanks for the help, I'll keep after it.

 

[NEKExplorer]

Also, one other fun part of the mix- the instrument cluster in the '99 was electronic/LCD whereas the 98 is all analog- I am hoping that works to my favor

 

[phattyduck]

Plug 'n play they said, just take the harness and ecu from the donor they said, lol.

Thanks for the help, I'll keep after it.

It is, as long as you don't cross sub-generations! 96-98, 99-00, 01-02.

'99 and '98 are very different, wiring-wise. The '99 dash harness won't work with the rest of your truck, so unless you want to swap everything over to '99 spec (EVERYTHING!), your best bet is to find a '98 manual trans ECU and use your original '98 harness(es) and modify it for the MT.

Your transfer case control is also different between the Limited push-button case and the manual J-shift case on the MT, so you have to figure that one out too (keep the push-button case or swap to the J-shift and change out the electronics for that).

-Charlie

 

[NEKExplorer]

Anybody help me find the correct part number for the wire Harness for 1998 3.4 4x4 M/T California emissions then? I have found the correct part number for the 98 M/T ECU and I guy who can find one, but I am having a very difficult time finding the correct part number for the wiring harness.

This posthttps://www.toyota-4runner.org/3rd-gen-t4rs/293904-5-speed-swap-wiring-diagram.html?fbclid=IwAR2XrZW8TLDrezqba4dPJZ3U7XRGXDIoot7SZCYOV-P_uBnjiFRDqZUVvHM

suggests that if I use that solution all I have to deal with is tricking the park/neutral switch part of the ignition circuit.


I have two part numbers listed for a VIN from a 4Runner that I believe would make the appropriate donor vehicle

The using that VIN, the part numbers I have found listed at toyotapartsdeeal as compatible are:

82111-3D701 (Canada spec) w/ ADD&ABS
82111-3D661 w/ADD&ABS


So- can anybody tell me or refer me to a site that will tell me which is the correct harness for my application?

Should also probably add it's the straight manual no push-button j-shift transfer case, ADD front diff, ABS

 

[RandyBobandy]

You should be able to use any 98 manual v6 harness, although I’m not sure about differences between Canada spec and the ones we have. You could also use a 98 auto harness and repin it for the manual ecu although that is probably harder.

I’m pretty sure there’s only one 98 M/T harness since they all have J shift cases

 

[NEKExplorer]

Thanks, I think I got my numbers now, got a couple guys looking for me, much more optimistic now.