ST205 IC / Code 54 Elimination circuit

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scothaniel

New member
Thanks to Greg (zblu81) , I was able to figure out the wiring combination to eliminate the code 54 error by fooling the ECU into thinking that the pump system is working fine. Here is the basic circuit I used - and it worked great! :

Code54-circuit.gif


The diode just keeps the power signal from back tracking to the ECU. May not be needed, but for $1 I'll play it safe.

For those of us without the manifold air temp sensor (tham), you can wire in a 1.5-3K resistor to make the ECU think the post intercooler air temp is nice and cold.
 
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Gary

Moderator
Few questions,
Is that NO type relay?
Which direction the diode is connected?
Cathode is on the top or bottom?
 
CMS-GT4

CMS-GT4

Active member
What about doing this at the ECU? Can I just bridge the wires through this resistor and prevenmt the code? I do not have wires in my engine bay for this since i used the 185 harness.
 
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scothaniel

New member
Relay is a standard 4-wire Normally Open relay.

Diode allows flow from ECU to Ground ( I can never remember which end the cathode is on, I always have do a continuity check).

What about doing this at the ECU? Can I just bridge the wires through this resistor and prevenmt the code? I do not have wires in my engine bay for this since i used the 185 harness.
Click to expand...

I did this at the ECU. I put the light bulb in the glove box (be careful, it gets really hot) and the relay is sitting next to the EFI relay. Most of the wire are under 12" long.
 
G

Gary

Moderator
scothaniel":3bd6tl4k said:
Diode allows flow from ECU to Ground ( I can never remember which end the cathode is on, I always have do a continuity check).
Click to expand...
In that case, it the cathode should be on the top.

code542ae.gif
 
CMS-GT4

CMS-GT4

Active member
I was going to wire in my tham. Should I follow the same methods? Also, is the bulb needed? And what relay am I conncting to?

I am still a wiring noob. Thanks for you help.
 
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scothaniel

New member
Pic updated, thanks!

I would assume that you could use a 15 ohm / 10 watt resistor in place of the bulb, but I know the bulb works.
 
CMS-GT4

CMS-GT4

Active member
What wire should I tap into for a 12V power source? I think I have all the bits I need.

I am also going to post pics of what I put together.

What purpose does the bulb serve?
 
CMS-GT4

CMS-GT4

Active member
I am not sure myself, but I think this is how they are linked at the harness from the factory. So, if it is, they should not.

I am not much for wiring myself, and hope I have gathered enough info from this thread to do this right.
 
A

Acadian alltrac

New member
Hi,

I just wanted to let you know that I did the circuit with the light, works fine for me! No more check engine (code 54 and 23) and its been like 2 weeks now. Now running full boost for the first time!! It's great!

Thanks,

André
 
CMS-GT4

CMS-GT4

Active member
Here is how to setup the resistors, thanks to gary. Fixed both code 54 and 23. I grounded the water level snsor and that was the last step.
 
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