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Discussion Starter · #1 · (Edited)
I found a 3.4L from a 98 Tacoma with a manual transmission with low miles. And I'm looking to swap it into my high mileage 02 3.4L with a manual transmission. The 98 has a diagnostic plug under the hood. My 02 has the standard OBDII diagnostic plug under the dash.

I'm guessing at minimum there's a engine wiring harness swap that needs to happen.
Does anyone know what it takes to make this swap?

*** Edited year from 01 to 02
 

· Mambeau / Admin
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(1) Welcome to CT!

(2) I'm confused by your reference to the OBDII plug(s).

On 1995.5 - 2001 5VZ Tacomas there were two diagnostic plugs:

  • The Data Link Connector 1 (DLC1) in the engine bay
  • The DLC3 (OBDII plug) in / behind the center dash

In other words, as far as I know both the '98 and '01 5VZ Tacos had both plugs, located in the same places.
 

· Mambeau / Admin
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I'm not sure, but there may be some tricky adaptation(s) needed because of changes to the emissions systems / specs.

The 1998 engine (and manifold / exhaust components) were designed for general / federal emissions specs.

In the 2000 model year the emissions stuff was divided into two separate specs / groups: federal and the stricter California (LEV) standards.

Effective with the 2001 model year all 5VZs were compliant with the California / LEV standards used in the 2000 model year.
 

· Mambeau / Admin
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There was a change in the 5VZ engine mount in 2000:

The mounting angle of the front engine mount has been optimized to reduce vibration.
This is the extent of what the factory documentation says. I don't know whether this would require any adaptation in doing the swap.
 

· Mambeau / Admin
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... In the 2000 model year the emissions stuff was divided into two separate specs / groups: federal and the stricter California (LEV) standards.
Effective with the 2001 model year all 5VZs were compliant with the California / LEV standards used in the 2000 model year.
The LEV adaptations for the 2RZ / 3RZ 4-cylinder engines involved intake port differences, valve timing differences, and some other changes.

According to the 2000 model year new features documentation there were no such structural adaptations on the 5VZ 6-cylinder engines.
 

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Discussion Starter · #6 ·
(1) Welcome to CT!

(2) I'm confused by your reference to the OBDII plug(s).

On 1995.5 - 2001 5VZ Tacomas there were two diagnostic plugs:

  • The Data Link Connector 1 (DLC1) in the engine bay
  • The DLC3 (OBDII plug) in / behind the center dash

In other words, as far as I know both the '98 and '01 5VZ Tacos had both plugs, located in the same places.
(1) Welcome to CT!

(2) I'm confused by your reference to the OBDII plug(s).

On 1995.5 - 2001 5VZ Tacomas there were two diagnostic plugs:

  • The Data Link Connector 1 (DLC1) in the engine bay
  • The DLC3 (OBDII plug) in / behind the center dash

In other words, as far as I know both the '98 and '01 5VZ Tacos had both plugs, located in the same places.
Thanks for the welcome!

I did just edit my post. My truck is an 02. Not sure how I needed that up. The 98 engine came with the truck! I just checked and there's only a diagnostic (DLC1) plug under the hood. There could be an DLC2 plug in the cab but it is not located under the dash, near where the DLC2 plug is located in my 02.

No DLC1 plug on my 02 but that aligns with your info.

Would I need to swap engine wiring harness to use the 98 5VZ?
 

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Discussion Starter · #7 ·
There was a change in the 5VZ engine mount in 2000:



This is the extent of what the factory documentation says. I don't know whether this would require any adaptation in doing the swap.
Thank you, this is great info.

Do you think that change would be too the mount only?

I can't imagine changing the 5VZ block or the Tacoma frame.
 

· Mambeau / Admin
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RE: DLCx Connectors

Shifting from 2001 to 2002 changes a lot of things ...

All I can tell you is that both the 1998 and 2001 models had both DLC1 and DLC3 connectors.

I've checked the wiring diagrams, and it appears the DLC1 (engine bay) connector disappeared for the 2002 model year, but a DLC3 connector remained behind the center dash.

I don't know what this means. There were a number of emissions-related changes made to 5VZ engine control for the 2002 model year. I can't find any factory documentation stating the DLC1 connector was removed for the 2002 model year.

Here (attached) is the factory document describing changes for the 2002 model year. It describes all the stuff that was changed with the emissions equipment, but never mentions the DLC1 being eliminated.
 

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· Mambeau / Admin
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Here (attached) are the 1998 and 2002 5VZ engine control wiring diagrams. Note that the DLC1 connector was wired from the ECM, and there's no corresponding ECM terminal on the 2002 model.

I have no idea whether this suggests there are ECM wiring connections that have to be adapted or re-rigged to make the swap work.
 

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· Mambeau / Admin
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RE: Engine Mount Change

Do you think that change would be too the mount only? I can't imagine changing the 5VZ block or the Tacoma frame.
What I quoted earlier is all I can find on this change. At face value it only says the mount's angle was changed to reduce vibration. I don't know whether this angle change makes any difference for swapping in a different 5VZ.
 

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Discussion Starter · #11 ·
Thank you @Enola Gaia!

I think I'm going to go for it. I'll report back here when I'm done.

I'll plan to swap wiring harness and hope any additional sensors can be swapped. Including emissions stuff.

And thank you for the tech data. I'll study it too.
 

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I found a 3.4L from a 98 Tacoma with a manual transmission with low miles. And I'm looking to swap it into my high mileage 02 3.4L with a manual transmission. The 98 has a diagnostic plug under the hood. My 02 has the standard OBDII diagnostic plug under the dash.

I'm guessing at minimum there's a engine wiring harness swap that needs to happen.
Does anyone know what it takes to make this swap?

*** Edited year from 01 to 02
Swapping the 3.4L engine from a 1998 Tacoma with a manual transmission into a 2002 3.4L vehicle with a manual transmission is a significant undertaking and should not be attempted without proper knowledge and tools. Here is a list of the steps that would generally be involved in such a swap:
  1. Gather all necessary tools and equipment: This will likely include basic hand tools such as wrenches and sockets, as well as specialized tools like engine hoists and transmission jacks.
  2. Remove the old engine: This will generally involve disconnecting the battery, draining the coolant, removing any accessory components that are in the way (such as the radiator or exhaust manifold), and unbolting the engine from the engine mounts.
  3. Install the new engine: This will involve placing the new engine onto engine mounts, connecting all necessary accessory components (such as the radiator and exhaust manifold), and attaching the engine to the transmission.
  4. Wiring harness swap: As you mentioned, the 98 Tacoma has a diagnostic plug under the hood, while the 02 vehicle has an OBDII diagnostic plug under the dash. In order to make the swap work, you will need to swap the entire wiring harness from the 98 Tacoma onto the 02 vehicle. This can be a complex and time-consuming process, as it will involve disconnecting and reconnecting a large number of wires and connectors.
  5. Fluid changes: After the engine swap is complete, you will need to refill the engine with oil and coolant, as well as bleed the air out of the cooling system.
  6. Test and adjust: Once everything is connected and in place, it will be necessary to start the engine and test it to ensure that it is running properly. If there are any issues, they will need to be addressed before the vehicle is driven.
It's worth noting that this is just a general overview of the process, and there may be additional steps or complications that arise depending on the specific vehicles involved and the condition of the components. Swapping an engine is a complex and technical task that should only be attempted by those with the necessary skills and experience.
 
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