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1998 2.5 RS
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Discussion Starter · #1 ·
:help:

Ok so here is what I have found. I'm hoping someone can help me diagnose this problem.

Background:
98 RS being swapped with 2007 WRX engine. Wiring is complete. I was pretty thorough (or so I thought), when checking and double checking connections.

Symptoms:
When I turn the key on I get no CEL, no Fuel Pump, and the fans run continuously (Test Connector is unplugged).

Using the Diagnostic section of the service manual I have found that all power (backup, and ignition), as well as grounds (engine, body, and sensor, which I believe are through the ecu because I only got the sensor grounds when I had the ecu in) are good. The problem is I only get 2.5V to the main relay pin 3. The diagnostic section says this should be between 10-13V. Also there is no power to the FPC (should be 0 or 5V on the one pin, and 10-13V on the other). I also can not connect to the ECU using Accessport.

Any ideas on what might be my culprit? I thought I was ready to try to start it up, but I get this. I'm hoping for something stupid, and not a bad ECU.
 

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2006 WRX
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611 Posts
Almost sounds like your ignition switch isn't connected. Maybe you mixed up the fan wire and ignition switch?
 

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1998 2.5 RS
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1,744 Posts
Discussion Starter · #3 ·
Well that certainly would be stupid (although not completely out of the question), but I get power to the ECU on the right pin from the ignition (B135-19) when I turn the key to ON.
 

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1998 2.5 RS
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Discussion Starter · #5 ·
Yeah everything else gets power and works like normal. All fuses under the hood, and in the dash are good as well.
 

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1998 2.5 RS
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1,744 Posts
Discussion Starter · #7 ·
I tested directly at the pins from the ECU (B134-7 and B135-2) and there is only 2.5V there also. Could that still be the relay?
 

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2000 Impreza++
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66 Posts
oh man this is exactly how my swap is behaving. I am using the original main relay as well as the fuel pump relay, and merged the 07 wrx engine harness with the 00 RS bulkhead. What I realized is that the main relay control(coil) circuit is way different for the WRX when compared to the RS.

The RS circuit is powered from the ecu and ends as a ground after the relay.
The WRX circuit ends into the ecu and has it's power sourcebefore the relay.

My guess is this is causing our power issue. I will be testing my theory today.
 

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2006 WRX
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611 Posts
from Brydon:

Fuel Pump Relay Control B134/16 – B135/19
^^^****The Opposite side of the fuel pump relay now needs to be ground instead of power. The Main Relay needs to be power instead of ground. This can be done by swapping the Main Power Relay and Fuel Pump Relays power and ground. These are the wires opposite the side that go back to the ecu****
 

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2006 WRX
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611 Posts
Which steering column are you guys using? And what keys do you have? The 06+ WRX's (in Canada at least) have chips in the keys. Your car won't start without the proper code.
My CEL was turning on and fuel pump was priming. Everything worked normally except it wouldn't fire when I cranked the car. You were there for pretty much the maiden voyage after my key was programmed.
 

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1998 2.5 RS
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Discussion Starter · #12 ·
from Brydon:

Fuel Pump Relay Control B134/16 – B135/19
^^^****The Opposite side of the fuel pump relay now needs to be ground instead of power. The Main Relay needs to be power instead of ground. This can be done by swapping the Main Power Relay and Fuel Pump Relays power and ground. These are the wires opposite the side that go back to the ecu****
Can I just switch the terminals inside the plugs, or do I need to run new wires?

Which steering column are you guys using? And what keys do you have? The 06+ WRX's (in Canada at least) have chips in the keys. Your car won't start without the proper code.
That isn't what is causing the problem (yet :) ). I have the key and the antenna up in the dash, but from what I've read not having that wouldn't keep it from turning on the ECU.
 

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1998 2.5 RS
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1,744 Posts
Discussion Starter · #14 ·
You can just do this: Cut power/ground for fuel pump relay. Switch the 2 wires, solder. Repeat for main relay.
Do this right at the plug? Is it ok if I have spliced other things into these wires (not sure if I have need to recheck), or is it only the relays that need to be switched?
 

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1998 2.5 RS
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Discussion Starter · #16 ·
Wow I can't believe I read that so many times and missed that. Thanks for directing me to the right place.
 

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1998 2.5 RS
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Discussion Starter · #17 ·
Ok before I do this, I want to double check what I see in the diagrams.

I need to switch Pin 1 on the Main Relay from Ground to Power (07 WRX goes to SBF-5). Can I splice into Pin 5 or 6 of the Main Relay (Both go to SBF-5)?

Also, Pin 3 of the Fuel Pump Relay changes from IGN Power (FB-11, or B135-19) to Ground (I tied B84-32 into the B135-19 for some reason, can't remember why now, it just seemed right then :( ). I will get this from my old Pin 1 on the Main Relay.
 

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2000 Impreza++
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66 Posts
That's what you need to do, since the 07 wrx ecu and RS ecu have different circuit configurations. I verified against my diagrams as well.
 
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