HELP!?! 5-speed swap Tacoma ECU no power

[Huey.Raine]

I have a ‘02 4Runner Sport Edition with a 5 speed swap. The only wiring done was to tie the 2 neutral wires together to get it to run with the factory ECU. 4Runner has ran with zero issue this way for 2 + years and 30k + miles. I got tired of staring at the CEL, VSC, ABS lights and bought a Tacoma ECU, which from what I read on here was plug and play and would fix the lights.

It’s from a ‘04 v6 4wd 5 speed Tacoma. It has no warranty, but the place I bought it from is pretty reputable and said it was taken from a Tacoma that was totaled due to being rear ended.

Did I get a bad ECU or is there something else I have to do to get it to work? The CEL doesn’t even come on now. Everything else lights ups and the truck sounds like it’s trying to turn over but nothing happens. It’s dead.

 

[Huey.Raine]

Add…

Swapped the stock ECU back in and it works fine. CEL is completely dead with the Taco ECU, even in the ACC position, which leads me to think it’s not getting any power.

I have the neural safety wires jumped together so it would start with the stock ECU. I never wired the clutch cancel, cruise control, reverse lights. Not sure if maybe any of that is causing the issue?

 

[Bad Luck]

Have you looked at wiring diagrams or ecm connector pin outs for both ecm’s to verify it’s the same?

 

[Huey.Raine]

Have you looked at wiring diagrams or ecm connector pin outs for both ecm’s to verify it’s the same?

I have not, but there are dozens of writeups online that say a 03-04 Tacoma v6 4x4 5 speed ECU is a direct plug and play for 01-02 4Runner 5 speed swap.

Other than bad luck getting a bad ECU, which I feel is unlikely, the only thing I can think is that it’s because I don’t have the neutral switch wired correctly. To drive with the swap using the factory ECU the only thing required was to jump 2 of the wires off the NSS together. You get CEL/VSC/ABS warning lights and the cruise control and reverse lights don’t work and it’s essentially a permanent clutch start cancel mode, but it is drivable just jumping the 2 wires together.

But I have seen diagrams where the NSS is used to tie in the clutch cancel start, cruise control and reverse lights when using a 03-04 Tacoma ECU with the factory engine wiring harness. The only thing I can think is that wiring the neutral safety switch into the clutch is required to complete the circuits on the Taco ECU.

 

[St Runner]

I think your problem is that the Tacoma ECU is looking for the clutch start switch and not the NSS. Even though the plugs match fine, the wires are in different locations on the plug. Get a wiring diagram and figure out which wire the tacoma ecu needs to go to the clutch starting circuit and ground it or run it to the clutch the way it is supposed to

 

[Huey.Raine]

I think your problem is that the Tacoma ECU is looking for the clutch start switch and not the NSS. Even though the plugs match fine, the wires are in different locations on the plug. Get a wiring diagram and figure out which wire the tacoma ecu needs to go to the clutch starting circuit and ground it or run it to the clutch the way it is supposed to

Yeah, I think this is the issue. I’m gonna try to fix it tonight or sometime this weekend.

To make the vehicle crank and run with the 5 speed and auto ECU all that was needed was to short out 2 of the wires together on the NSS to Truck the ECU into thinking the vehicle was in neutral.

I’ve found a few diagrams online that show how to wire up the clutch cancel, cruise, reverse lights, etc using the wires on the NSS plug from the auto engine harness to work properly with a Taco ECU.

Only problem is I don’t think I have the wire end of the plugs that connect to the clutch pedal sensors. I’m pretty sure all my pedal assembly has is the actual switches with the female ends and missing the male ends with the wires. So I’ll either have to source those plugs or figure out a way around it.

 

[St Runner]

I would start by looking at a wiring diagram for the tacoma ecu and find the exact pin the starting circuit is on. Then check the plug for that pin and see which wire( if any) is attached to it. Follow that connection to the body harness, usually just to the right of the ecu. Depin or cut the wire and ground it to the body and it should start if that is the only problem. All the clutch start switch does is ground the starting circuit when you push the pedal or push the button

 

[Team_Jake]

the truck sounds like it’s trying to turn over but nothing happens. It’s dead.

Do you have a blinking red security light somewhere in your interior? Either next to your tailgate window up/down switch, or to the left of your steering wheel? If so, it's an immobilizer issue, your answer is in this thread here.

 

[Huey.Raine]

Do you have a blinking red security light somewhere in your interior? Either next to your tailgate window up/down switch, or to the left of your steering wheel? If so, it's an immobilizer issue, your answer is in this thread here.

No I don’t think my 4R has an immobilizer. It’s an SR5 Sport Edition and it doesn’t have the security plate with the light anywhere on the dash.

 

[Huey.Raine]

Update…

I’ve found a diagram that shows how to wire the clutch pedal, cruise and reverse lights using the NSS switch off the auto engine harness so that the Taco ECU will work. I verified with someone who’s done the swap that it will work.

Now my issue is all I have is the physical switches that mount to the clutch and no wiring. I need the pigtail ends that come from the engine harness so I can plug them into the switches and wire them back to the NSS switch from my auto harness.

Anybody know where those can be sourced? Junk yards within 100 miles of me very rarely have anything 95-04 Tacoma or 96-02 4Runner.

 

[Team_Jake]

For wiring, refer to this:
5-Speed Swap Wiring Diagram

For now, all you need to do is jump wires 5&6 together from the P/N Safety Switch to make the ECU think the clutch switch is working.

From what you described though, your issue does NOT sound like a clutch switch issue, it sounds like an immobilizer issue. If your engine is only turning over, meaning it's cranking but not actually starting, it's an immobilizer issue. If you don't have an immobilizer in your 4Runner, it must mean the Tacoma the ECU came from had an immobilizer and is refusing to start as a result. Before jumping down this rabbit hole though, could you describe exactly what is happening when you turn the key with the Tacoma ECU?

 

[Huey.Raine]

For wiring, refer to this:
5-Speed Swap Wiring Diagram

For now, all you need to do is jump wires 5&6 together from the P/N Safety Switch to make the ECU think the clutch switch is working.

From what you described though, your issue does NOT sound like a clutch switch issue, it sounds like an immobilizer issue. If your engine is only turning over, meaning it's cranking but not actually starting, it's an immobilizer issue. If you don't have an immobilizer in your 4Runner, it must mean the Tacoma the ECU came from had an immobilizer and is refusing to start as a result. Before jumping down this rabbit hole though, could you describe exactly what is happening when you turn the key with the Tacoma ECU?

When I installed the Tacoma ECU and turned the key to ACC everything appeared to turn on and be normal. But then when trying to start the 4R it just constantly turned over without actually starting. Then I noticed that the CEL was completely dead. It didn’t even illuminate with the key in ACC position. I reinstalled the 4R ECU and it fired right up as normal. And as stated before, I’ve put over 30k miles on the vehicle since the swap and it’s been flawless.

I pulled the Tacoma ECU from a totaled, but running, ‘04 v6 4x4 5-speed Tacoma.

It has the 2 wires in the NSS plug jumped already, that’s how I’ve been driving around. I bought the Tacoma ECU to correct the CEL/VSC/ABS lights and properly wires in the clutch start cancel, cruise and reverse lights.

Is it possible to disable the immobilizer in the ECU? My 4R does not have one, but I think you’re right in thinking the Tacoma ECU does.

 

[Team_Jake]

When I installed the Tacoma ECU and turned the key to ACC everything appeared to turn on and be normal. But then when trying to start the 4R it just constantly turned over without actually starting. Then I noticed that the CEL was completely dead. It didn’t even illuminate with the key in ACC position. I reinstalled the 4R ECU and it fired right up as normal. And as stated before, I’ve put over 30k miles on the vehicle since the swap and it’s been flawless.

I pulled the Tacoma ECU from a totaled, but running, ‘04 v6 4x4 5-speed Tacoma.

It has the 2 wires in the NSS plug jumped already, that’s how I’ve been driving around. I bought the Tacoma ECU to correct the CEL/VSC/ABS lights and properly wires in the clutch start cancel, cruise and reverse lights.

Is it possible to disable the immobilizer in the ECU? My 4R does not have one, but I think you’re right in thinking the Tacoma ECU does.

Yep, it is absolutely an immobilizer issue. I don't know if this will work but it is worth a shot - there are 5 connectors that plug into the ECU. Try disconnecting the center plug from the ECU, and then see if it starts. If that does not work, you need to have your ECU re-flashed, I can help you through that.

 

[Huey.Raine]

Yep, it is absolutely an immobilizer issue. I don't know if this will work but it is worth a shot - there are 5 connectors that plug into the ECU. Try disconnecting the center plug from the ECU, and then see if it starts. If that does not work, you need to have your ECU re-flashed, I can help you through that.

Which plug are you talking about? Because the Tacoma ECU already had one plug that wasn’t used. There were 5 plugs on my 4R ECU and one of the middle ones on the Tacoma ECU was blank with no pins in it. I want to say that one was the 2nd from the right but it may have been the middle one. I’d have to check it when I get home to confirm which one, though. Is that the one you’re talking about, or is it a different one?

If the ECU needs reflashed I can possibly do it if I have detailed instructions. I’m fairly mechanically inclined, former Marine Corps helicopter mechanic
and now a manufacturing maintenance technician in the civilian world, but I’m admittedly not the greatest when it comes to electrical stuff.

 

[Team_Jake]

Which plug are you talking about? Because the Tacoma ECU already had one plug that wasn’t used. There were 5 plugs on my 4R ECU and one of the middle ones on the Tacoma ECU was blank with no pins in it. I want to say that one was the 2nd from the right but it may have been the middle one. Is that the one you’re talking about, or is it a different one?

If the ECU needs reflashed I can possibly do it if I have detailed instructions. I’m fairly mechanically inclined, former Marine Corps helicopter mechanic
and now a manufacturing maintenance technician in the civilian world, but I’m admittedly not the greatest when it comes to electrical stuff.

If you have one blank plug, that's where the immobilizer gets plugged in, so it looks like that method won't work. The thread I linked in post #8 will get you started. If you are good with computers then maybe it's within your skill set, it gets very complicated though.

I know [MENTION=139000]phattyduck[/MENTION] had this exact issue at one point, I would like to ask him to chime in just to get a second opinion.

I know [MENTION=315156]Brian.[/MENTION] can get your ECU re-flashed if you send it to him. Best of luck!

 

[Huey.Raine]

If you have one blank plug, that's where the immobilizer gets plugged in, so it looks like that method won't work. The thread I linked in post #8 will get you started. If you are good with computers then maybe it's within your skill set, it gets very complicated though.

I know [MENTION=139000]phattyduck[/MENTION] had this exact issue at one point, I would like to ask him to chime in just to get a second opinion.

I know [MENTION=315156]Brian.[/MENTION] can get your ECU re-flashed if you send it to him. Best of luck!

Well, now I’m confused.

The blank plug is on the Tacoma ECU. If it has an immobilizer why would it be blank?

I may be wrong but I’m almost certain my 4R does not have an immobilizer. There’s no Security plate and light anywhere on the dash and it only came with a single blank valet key when I bought it.

 

[Bad Luck]

Well, now I’m confused.

The blank plug is on the Tacoma ECU. If it has an immobilizer why would it be blank?

I may be wrong but I’m almost certain my 4R does not have an immobilizer. There’s no Security plate and light anywhere on the dash and it only came with a single blank valet key when I bought it.

Since your 4Runner doesn't have an immobilizer there isn't a plug in the 4Runner harness for the immobilizer stuff. (The immobilizer is part of the ECU.) If the Tacoma ECM had an immobilizer then that Tacoma would have had a plug for the ECM immobilizer in the Tacoma vehicle harness. Does that make sense?

 

[phattyduck]

I know [MENTION=139000]phattyduck[/MENTION] had this exact issue at one point, I would like to ask him to chime in just to get a second opinion.

The research I've done is for removing the immobilizer from an ECU to use it in a non-immobilizer 4Runner.... so not quite the same.

I'd definitely suspect a minor wiring incompatibility, but even then, the Check-Engine light should illuminate with the key in the "ON" position with the engine off.

If you can't find diagrams online, get a 2-day subscription to the Toyota TIS system and download what you need...

-Charlie

 

[Huey.Raine]

Since your 4Runner doesn't have an immobilizer there isn't a plug in the 4Runner harness for the immobilizer stuff. (The immobilizer is part of the ECU.) If the Tacoma ECM had an immobilizer then that Tacoma would have had a plug for the ECM immobilizer in the Tacoma vehicle harness. Does that make sense?

I can upload a photo comparing them in a few mins when I get home to explain it better. But what I’m saying is the 4Runner ECU has pins and plugs in every port on the ECU. The Tacoma ECU has a port that is completely blank.

 

[Huey.Raine]

The research I've done is for removing the immobilizer from an ECU to use it in a non-immobilizer 4Runner.... so not quite the same.

I'd definitely suspect a minor wiring incompatibility, but even then, the Check-Engine light should illuminate with the key in the "ON" position with the engine off.

If you can't find diagrams online, get a 2-day subscription to the Toyota TIS system and download what you need...

-Charlie

That’s what I’m trying to do: install an immobilizer Taco ECU into a non-immobilizer 4Runner.