98 SR5 Engine into a Limited Chassis - which wiring harness/ECU to use?

[phattyduck]

There are different clusters between the SR5, Limited, and limited with AWD.

The '96-'98 clusters are all the same (only engine/trans different, not by trim - though they do vary by year also) since the Limited case is not AWD. Just one 4WD light, like the j-shift case.

The Limited dash wiring is different than the base/SR5 wiring. The Limited has a computer in the driver's footwell, the base/SR5 uses a 'simple' relay in the passenger footwell.

There's some challenges here - do you want to swap over to the SR5 control style? Do you want to try to use the 4WD computer? In either case, there are some challenges...

Even the j-shift has to actuate the front VSVs and uses a few detection switches to drive the dash light.

-Charlie

 

[clearock]

[MENTION=139000]phattyduck[/MENTION] thank you for the schooling

I parted a 98 (or so my memory thought), must have been a 99 limited with AWD cluster with the center AWD pic.

 

[farmerjon]

The '96-'98 clusters are all the same (only engine/trans different, not by trim - though they do vary by year also) since the Limited case is not AWD. Just one 4WD light, like the j-shift case.

The Limited dash wiring is different than the base/SR5 wiring. The Limited has a computer in the driver's footwell, the base/SR5 uses a 'simple' relay in the passenger footwell.

There's some challenges here - do you want to swap over to the SR5 control style? Do you want to try to use the 4WD computer? In either case, there are some challenges...

Even the j-shift has to actuate the front VSVs and uses a few detection switches to drive the dash light.

-Charlie

Confirmed 4WD is not engaging when I throw the jshift. It seems that the ADD is not engaging because it doesn’t know how, like you said.

I’d like to try to do this the sr5 style but I’m really curious how that works. I’ve already moved over the SR5 computer - do I need a wire from the computer to the dash? Or that my VSVs are likely not working? No way of knowing if those ever worked on this new truck so maybe I need to research the VSV vacuum test?

 

[phattyduck]

Confirmed 4WD is not engaging when I throw the jshift. It seems that the ADD is not engaging because it doesn’t know how, like you said.

I’d like to try to do this the sr5 style but I’m really curious how that works. I’ve already moved over the SR5 computer - do I need a wire from the computer to the dash? Or that my VSVs are likely not working? No way of knowing if those ever worked on this new truck so maybe I need to research the VSV vacuum test?

You seem to be confusing a few things here. The engine ECU has no control over the 4WD system. You could have left the Limited engine ECU in there, no problem. Push-button and multi-mode cases have a separate 4WD ECU. J-shift cases just use a simple relay - those parts are located on opposite sides of the interior... and the wiring for the 'other' option is not there for a given trim (though each 2WD trim does have the matching plugs for its version of 4WD).

A 'universal' 5-pin relay can work in place of the custom ADD relay using the wires that are at the 4WD computer location. The wire color and function match for what you are doing between the push-button case and j-shift case.

TIS

Get a 2-day membership, download the diagrams for your 4Runner and go to town!

-Charlie

 

[farmerjon]

You seem to be confusing a few things here. The engine ECU has no control over the 4WD system. You could have left the Limited engine ECU in there, no problem. Push-button and multi-mode cases have a separate 4WD ECU. J-shift cases just use a simple relay - those parts are located on opposite sides of the interior... and the wiring for the 'other' option is not there for a given trim (though each 2WD trim does have the matching plugs for its version of 4WD).

A 'universal' 5-pin relay can work in place of the custom ADD relay using the wires that are at the 4WD computer location. The wire color and function match for what you are doing between the push-button case and j-shift case.

TIS

Get a 2-day membership, download the diagrams for your 4Runner and go to town!

-Charlie

Thanks Charlie. I appreciate your patience. Worth the effort to pull the SR5 wiring/relay from the SR5 truck and move it over to the Limited?

The problem with the Limited is that it has a wire that goes to the push button shifter (in the cab, to the computer). The SR5 seems to use the 4WD position sensors on the case itself to activate the relay - does that sound right?

 

[phattyduck]

Thanks Charlie. I appreciate your patience. Worth the effort to pull the SR5 wiring/relay from the SR5 truck and move it over to the Limited?

The problem with the Limited is that it has a wire that goes to the push button shifter (in the cab, to the computer). The SR5 seems to use the 4WD position sensors on the case itself to activate the relay - does that sound right?

Since you have an SR5 to pull parts from, grab the relay and 'pigtail' for the wiring.

The push button on the Limited 'asks' for the 4WD shift for the 4WD ECU. There is still a position switch on the Limited T-case to signal the shift has been completed. This wire is connected to the 4WD switch on the j-shift case already (its basically the same switch, if not the exact same switch). In either case, it is the signal that shows the t-case is in 4WD, which then triggers the ADD VSVs to engage the front drive. On the Limited, this happens via the 4WD computer. On the base/SR5, this happens via the ADD relay.

-Charlie

 

[farmerjon]

Since you have an SR5 to pull parts from, grab the relay and 'pigtail' for the wiring.

The push button on the Limited 'asks' for the 4WD shift for the 4WD ECU. There is still a position switch on the Limited T-case to signal the shift has been completed. This wire is connected to the 4WD switch on the j-shift case already (its basically the same switch, if not the exact same switch). In either case, it is the signal that shows the t-case is in 4WD, which then triggers the ADD VSVs to engage the front drive. On the Limited, this happens via the 4WD computer. On the base/SR5, this happens via the ADD relay.

-Charlie

I'm unsure where I would put the relay and how the pigtail would work. It appears to be labeled transmission relay on my SR5. I know nothing about wiring and schematics are hard to understand.

At this point, I'm considering pulling the dash of both trucks and moving the wire loom over, then I can unplug the 4WD computer as well. Simpler and harder to mess up, I'm thinking - but unsure how hard the dash is, going to research that.

 

[phattyduck]

I'm unsure where I would put the relay and how the pigtail would work. It appears to be labeled transmission relay on my SR5. I know nothing about wiring and schematics are hard to understand.

At this point, I'm considering pulling the dash of both trucks and moving the wire loom over, then I can unplug the 4WD computer as well. Simpler and harder to mess up, I'm thinking - but unsure how hard the dash is, going to research that.

You think that swapping an entire dash harness and HVAC system is easier than soldering 5 wires? Hmmm...

Once the Limited 4WD computer is unplugged and removed, there should be plenty of space for a the ADD relay from the SR5...

-Charlie

 

[farmerjon]

You think that swapping an entire dash harness and HVAC system is easier than soldering 5 wires? Hmmm...

Once the Limited 4WD computer is unplugged and removed, there should be plenty of space for a the ADD relay from the SR5...

-Charlie

Agreed but anything electrical or paint, I avoid with passion.

 

[farmerjon]

You think that swapping an entire dash harness and HVAC system is easier than soldering 5 wires? Hmmm...

Once the Limited 4WD computer is unplugged and removed, there should be plenty of space for a the ADD relay from the SR5...

-Charlie

Per your recommendation, Charlie, I got the diagrams from the Toyota TIS. Comparing the diagrams - I have 2 black/yellow wires on the ADD relay, and only one on the 4WD ECU. Posting diagrams below as attachments, the problem is knowing what to do with the extra black/white wire, #1, that goes to to the junction connector. I don't have a rear diff lock, and the only diagram I have for the Limited 4WD seems to show the diff lock setup.

Attached PDFs of wiring diagram on the next post (page 3).

 

[farmerjon]

PDFs attached.

 

[farmerjon]

PDFs attached.

Studying this further, I cut the ADD 2WD, 4WD wires (1,2) and the 4WD position switch wire (3), as well as the single black/yellow from the 4WD ECU, and wired them to the SR5 ADD Relay. Did not light up the dash or engage 4WD at all. I have an extra black/yellow wire on the ADD Relay, and I switched off the black/yellow connected to the ECU one, no changes.

Should I combine all 3 black/yellow wires since they are already joined in the junction boxes?

 

[phattyduck]

Per your recommendation, Charlie, I got the diagrams from the Toyota TIS. Comparing the diagrams - I have 2 black/yellow wires on the ADD relay, and only one on the 4WD ECU. Posting diagrams below as attachments, the problem is knowing what to do with the extra black/white wire, #1, that goes to to the junction connector. I don't have a rear diff lock, and the only diagram I have for the Limited 4WD seems to show the diff lock setup.

Attached PDFs of wiring diagram on the next post (page 3).

A junction connector is just that - a shorted connection between the wires. Solder the one Black-Yellow wire that originally went to the 4WD ECU to both of the Black-Yellow wires on the ADD relay. None of them are high current, they just need to be connected.

-Charlie

 

[TylerT252525]

If I swapped an engine from a 2002 tundra into a 2001 4Runner would I need to swap the ECU into the 4Runner as well?
I’ve already done the engine swap and used the 4Runner harness and ECU. It runs but has very little power when accelerating.

 

[phattyduck]

If I swapped an engine from a 2002 tundra into a 2001 4Runner would I need to swap the ECU into the 4Runner as well?
I’ve already done the engine swap and used the 4Runner harness and ECU. It runs but has very little power when accelerating.

Assuming you used a Tundra 5VZ...

I'd bet something mechanical is wrong - timing belt off one tooth, etc.

-Charlie

 

[farmerjon]

A junction connector is just that - a shorted connection between the wires. Solder the one Black-Yellow wire that originally went to the 4WD ECU to both of the Black-Yellow wires on the ADD relay. None of them are high current, they just need to be connected.

-Charlie

Thanks Charlie, I got it hooked up with the correct wires... soldered and all, and no light or engagement. I tried switching the vacuum hoses on the VSVs and the front diff + light immediately engage if the shifter is already in 4HI.

Based on other reading, I'm wondering if the issue is the ADD relay, if it is not sending signal to the VSVs to switch? Or is there an actuator or something in the VSVs themselves I can test? I believe before the engine swap, the VSVs worked in the Limited. I was having an issue with a the shifter not wanting to physically move at all in the SR5 transfer case before the swap but I blamed that on the shifter linkage "clip" and I re-set all that, but it might still be an issue.

Thoughts on next steps? Find another ADD relay?

 

[phattyduck]

That's good progress. Do you hear the ADD relay clicking when you go in and out of the 4WD shifter position? (key on or engine on)

Can you check for 12V at each VSV connector? Report back based on wire colors at the connector. Only one should have 12V at any time, once again, key on or engine on.

-Charlie

 

[farmerjon]

That's good progress. Do you hear the ADD relay clicking when you go in and out of the 4WD shifter position? (key on or engine on)

Can you check for 12V at each VSV connector? Report back based on wire colors at the connector. Only one should have 12V at any time, once again, key on or engine on.

-Charlie

Got through the winter and lots of life things. back to this finally. I got 12v on the brown plug with the accessory/key on. this is with the white/black wire and the teal green wire. This is with the jshifter at the 2WD position.

In the 4WD position, the brown plug keeps the 12v with the engine running.

ADD is wired up, can see the wiring I did above this post, about 3 posts up on this page.

Not sure I hear the clicking, I have a hearing loss so I am not able to hear very well. I got someone to listen for me, no clicking. No 12v power at the solder junction of the 3 black/yellow wires.

I assume, from research, I need to find a 12v power source to get the relay to click somehow? Maybe jump the 20a 4WD fuse from under the dash? Research suggests the 4WD ECU plug is dead because it is powered by the ECU itself? doesn't make sense why the black.yellow wire from the ECU plug would not provide power.

 

[farmerjon]

Since this moved from engine harness to wiring jshift transfer case, I moved my findings to an updated thread, as I've been benefiting searching tcase threads and would like others to find it easier:

'98 Limited: swap push button 4WD transfer case for 98 SR5 j-shifter tcase & ADD