Help understanding the gt4dc citcuit for code 54

CMS-GT4

Active member
That may be the case. At idle check, the ecu thinks things are fine its just when the INT runs its check, I get a fault. Wonder if there is a way I can just remove the circuit from the ecu.
 

WannabeGT4

New member
I bet if you open the ECU and trace INT back to the processor you'll find a burnt resistor or transistor somewhere along the way. Replace that/them and try it again.
 

CMS-GT4

Active member
I really do not have time to fix this. I may just have to buy ANOTHER ecu or something. I sort of wish I kept the mr2 one I bought. I bet it has been a burned out INT this whole time... I wasted a lot of time working on this.
 

CMS-GT4

Active member
I have another ecu on the way.

I am going to try this again when it gets here.

One quick question. Do I need to filter the 12v signal that goes to the INT of the ecu to reudce the 12v strength?
 

WannabeGT4

New member
CMS-GT4":myu090k3 said:
I have another ecu on the way.

I am going to try this again when it gets here.

One quick question. Do I need to filter the 12v signal that goes to the INT of the ecu to reudce the 12v strength?

That is the function of the relay's coil.
 

CMS-GT4

Active member
I followed this method.

Code54Elimination.gif


Car runs fine. I now get 9-10psi.
Error code is gone, but the light bulb from the circuit still does not light up. I hear the relay kick on when it does a pump check. Rock and roll. I test drove it. Pulls pretty well. I think it will pull even better once I install my boost guage. :evil:
 

WannabeGT4

New member
CMS-GT4":2tgljcmc said:
I followed this method.

Code54Elimination.gif


Car runs fine. I now get 9-10psi.
Error code is gone, but the light bulb from the circuit still does not light up. I hear the relay kick on when it does a pump check. Rock and roll. I test drove it. Pulls pretty well. I think it will pull even better once I install my boost guage. :evil:

Glad to here that got it working. Wanna send me your fried ST205 ECU ;).
 

aus jd 2703

New member
ok so im bringing this thread back to life lol
which is a better idea using this fix and hard wiring the pump or running the extra wires and wiring it to the ecu as toyota did?
im not sure which i rather do.
im putting a jap 205 into and australian st18 if it matter, and i plan t use the 205 ecu intercooler and water pump
 

CMS-GT4

Active member
If you have all the plugs and wiring from the 205 harness, then its not a bad idea to run the wiring as it would be stock. You do loose the option of constantly running pump though if you go that route.
 

lalojamesliz

New member
Hey guys I also did The gen3 electronics swap on my 91 all-trac and I'm using a gen3 mr2 ecu. I also have a st205 ecu that I want to use and I just bought the relay and some 1/4 watt 1k ohm resistors and some 1/2 watt 1k ohm resistors because I wasn't sure on what wattage to use. Would they both work or should I use the 1/4 or 1/2 watt? Also if I get rid of the code 54 with these things do I have to worry about the resistors or relay failing on me while driving? I have AAA towing but I don't want to jave to use it lol. Thanks guys
 

belanger33

New member
CMS-GT4":2vlgs1vr said:
I followed this method.

Code54Elimination.gif


Car runs fine. I now get 9-10psi.
Error code is gone, but the light bulb from the circuit still does not light up. I hear the relay kick on when it does a pump check. Rock and roll. I test drove it. Pulls pretty well. I think it will pull even better once I install my boost guage. :evil:

Bringing back this thread alive since i just did a gen3 conversion on my st185 RC and im getting code 54... To make sure , id like to recapitulate what i need exactly.... I need 2 1k resistors that i place at the ecu where the diagram shows it. Then i bridge the LEV sensor at the intercooler. Do i need to
Do something at the intercooler pump? ... Thanks for the clarification!
 

CMS-GT4

Active member
What intercooler pump are you using? Did you wire it to run all the time? Did you ditch the oem IC computer? The RC setup is a little different than the 205, so we need to know all you changed. Since this is an RC, if you still have the wta IC you can likely run a wire from the LEV to the sensor and still have it operate. If not, then you need to ground it at the ecu.
 

belanger33

New member
I have the RC WTA stock setup on with the stock pump on....i didn't do the job personnally so im not quite sure if i still the IC ECU. Is it situated at the same place the normal ECU is...Right now i did not ground anything and im just driving temporary with the code 54 error...
Is that enough info for you to help...
Thanks again!
 

CMS-GT4

Active member
Ok, so for your pump it just needs to be powered all the time, and it is done. If they did this part for you, then that is step one.

Next, you need to ground LEV at the ecu. Just have the wire come off the harness and ground it, unless you want to run it all the way to the working sensor.

Then you just need a standard 30amp relay and the 2 resistors to build the circuit like in the image. Just be careful to not fry anything. Make sure your doing the right wires etc... There is an ecu pin out in the st205 faq thread.
 

belanger33

New member
Alright so i understand the second part! However, how do you know that my pump
Is already running constant...
Thanks again
 

CMS-GT4

Active member
That's one you will have to figure out. Feel the hoses for water moving or listen to the pump. Only other options is to trace the wires and see if they go to a constant power source.
 

belanger33

New member
I Have some updates....I tried the relay solution like in the diagram on the last page but with no success....At first, i thought i had it because i had no more Check engine at idle, but when i drove out the parking the light went back on... I even switched the relay thinking it might not work properly but with no sucess...the LEV is grounded at ECU also...
Any suggestions now...:(
 

CMS-GT4

Active member
It not turning on till you drive is a sign that you grounded lev is functioning properly. It's the rest of the circuit that's the issue. Double check you built it right and check your connections for all the wires and solders.
 
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