DTC Codes and what to do with them?

[Handgrenade]

Hi guys, I have a question. My car is running and shifting and that's a giant feat in itself because it's a backyard swap. (the Maserati Biturbo Swap)

It seems like it's down on power. It seems like it should be much stronger than it is. Perhaps it is in limp mode but I have no way of finding that out, really.

I do have a check engine light wired in and I am able to pull codes.

We have a Code 12 which points to an RPM Signal #1 and we have a #42 VSS vehicle speed sensor signal which points to sensor #1. I ASSUME.
I've only just started reading up on these things. Rather than just start buying stuff, does anyone know exactly where the particular sensors are located specifically and the Ohms range for each? That way- I can check them before buying new ones?
Please advise and thank you for your time.

 

[George_R]

first of all, toyota's self diagnosis system is nothing remotely as fancy as one found on cars like audi, mercedes etc etc. It will only set some dtc if you do have serious problem.

And even if you see no dtc, the engine may be still malfunctioning so don't rely on the scanner data much. It's only a good start.

Regarding DTC 12, it's either CAS or, more likely in your case, wrong voltage at STA pin...for example ECU sees pulses from CAS and no voltage at STA, or vice versa

 

[Handgrenade]

I think my STA pin has 12v to it. I'll have to check, I'm fairly sure it does. I'm fairly certain it's been that way since the beginning. I will look into it. Would that put it into limp mode? I will begin there. As always, thanks George!

 

[George_R]

the only way to set limp mode using STA pin is to have constant 12V there
all other combinations may set DTC or may not, but engine performance will not be affected

as soon as you address the DTC12 you will have others things to check. You would need some needle voltmeter or a scope (even cheapest USB one is ok) for the most advanced part of the inspection list

 

[Handgrenade]

I have a decent voltmeter, and yeah I think I have 12v to STA as soon as the main switch is powered on. I will get out there in a few hours and see. I thought I did it like the book diagrams, but it's been so many weeks, I can't remember.

 

[George_R]

If you did it per the diagram, you will only observe 12V upon cranking .
Anything different is wrong

 

[Handgrenade]

My STA wire goes to the ECU. It has 11V (not 12) as soon as you turn on the main power. I ran it through a relay, but as I understand it, it should only get 12V when cranking. Let me see what happens when I connect it to the start button like that.

 

[Handgrenade]

OK, now the STA wire gets 12V when cranking. I took it from the starter button. I checked codes and now I get the same #42 and now I get a #43 which is the starter signal. Something's Effed up somewhere. Doesn't make sense.

 

[Handgrenade]

Ok, thankfully code #12 is gone.
I have code 42 and 43. Swapped ECU's and no change. When I connect the blue tooth Device, it shows open loop, I run engine to 3200RPM and it comes out of open loop as it should. Code 42 is because of the missing dash cluster, OK, no problem there. The blue tooth device shows no starter circuit data. I suppose I'll drive it and see what if anything has changed. Code #43 is the only unknown code at the moment.
Looking at the diagram, the starter circuit code 43 could be because there is a resister on the circuit and I might not be giving it the correct voltage?

 

[Handgrenade]

I just discovered the code 43 could in fact mean there is a traction control fault and I don't have any of that stuff on the car anyway. Some charts show 43 as a starter circuit and another shows it as a TRAC code.

 

[George_R]

It's amazing how people get everything fkt up with only two bloody ECU pins (STA,NSW)
ok so dtc12 is gone and that's quite an achievement

Now look at your NSW pin. What you should see is 0V in P,N and 12V in any other range. If not, fix it and DTC42 must be gone

43 is trac most likely, never mind it

 

[Handgrenade]

Hahaha, yeah I know, right? I've screwed them up 3 or 4 times now.

It's because of the way the diagram in the book shows it connecting. It looks to me as if you can tie them together because they're all going to the same place. I think the FK up comes when you don't use the Lexus gear selector. (Which I don't have)

My NSW wire is tied together with the STA wire and only gets 12V on cranking because I didn't know what else to do with it. The diagram shows it having a resistor at or near the Lexus gear selector, so I wasn't sure what to do with it. I have had it tied to 12V where it's powered 12v, as soon as you turn on the main switch. That works too if I remember correctly.

 

[George_R]

Getting it fkt up once more in a row won't hurt that much so don't worry, it just happened again

And Lexus selector has nothing to do with sta/nsw pins. The only thing involved is inhibitor switch located on the trans.

Make your car start only in P and N and that will make 99% of the work you need done.

 

[Handgrenade]

Hahaha, so what do I do with the NSW wire? I wondered why it starts in any gear... I thought it was because of the gear selector. Looks like it's back to school for me

 

[George_R]

Absolutely. First, connect your inhibitor switch per your wiring diagram.
Then I'll explain the rest. Otherwise anything I say will be of little use for you

Also, you may like his explanation better than mine
http://wilbo666.pbworks.com/w/page/45653482/Toyota NSW Engine ECU Pin

 

[Handgrenade]

I checked the NSW at the ECU. The wire is there, in the correct pin location. I checked at the transmission, the wire is there, the stock plug is in place. I did not continuity check the wire though, it still starts in any position.

 

[Handgrenade]

NSW and STA both have continuity from the plug on the transmission to the ECU. In theory, it should be working correctly.

 

[Handgrenade]

Excuse the large image, but:

The Park/Neutral switch and AT indicator as seen here in the upper right,
show the STA and the NSW running through this indicator.
My wiring is done this way, as seen in the diagram.
Continuity checks OK.
However, I'm not sure the R-L wire that feeds power TO the indicator switch, has 12v.
I will check to see if 12V is getting to the indicator.

 

[Handgrenade]

If you look at this guys diagram it seems to show the STA wire connected to the constant 12V and then grounded out when you send power to the starter:
http://wilbo666.pbworks.com/w/page/45653482/Toyota NSW Engine ECU Pin

I check my STA AND NSW wires, right at the ECU and they both have 12V when the car is running. And it starts in any gear.
If I ground the STA wire at any time, it will melt something.

 

[Handgrenade]

I checked the R-L wire at the indicator switch on the trans and it had no voltage when it was running. I added 12V to it and no change. It still starts in any gear. Bad indicator switch? Incorrect power feed to whole system? No clue at this point.