OB99W

Since the white heater wires read full battery voltage, it indicates that the ECU isn't pulling them towards ground at all. There are three possible causes: 1) The white wires could be going to the wrong ECU pins. I've now looked at many ECU pinout charts and wiring diagrams for the '03 and '04 WRX, and they all seem to agree with each other and with what you've reported. However, the ECU info from Subaru could be wrong -- I've found lots of errors in FSMs over the years, some minor, some not so minor. 2) The ECU A/F sensor heater control circuit could be defective. It's rare, but not impossible. 3) The ground wires used for the heater could be on the wrong ECU pins -- see 1). I'll admit to not being familiar with exactly what is necessary to perform the transplant that was done. Lushy, did this involve a lot of snipping/splicing, as EastCoastEJ22T has mentioned?

There are just too many model variations. I'd like a demotion! Otherwise, expectations are too high and I might not be able to live up to them...

You're welcome. We'll see how this goes after you post test results. Yes, that BR (black/red) wire is powered from the battery, via a slow-blow fuse (SBF-5), and should have 12 volts on it.

I looked around some more, and found ECU info here: http://www.northursalia.com/modifications/misc/wiring/wiring.html From the above site, '02/'03 WRX ECU pinout: http://www.northursalia.com/modifications/misc/wiring/wrxpin.html Also from that site, '04 WRX ECU pinout: http://www.northursalia.com/modifications/misc/wiring/04_DOHC_ECU.pdf For some reason best known to Subaru, they apparently changed (possibly in error) the numbering of some of the ECU connectors. It seems they are equivalent as follows: 02/03--04 B134--B134 B135--B135 B136--B137 B137--B84 B84---B136 Assuming the ECU info at NorthUrsalia is correct, and taking into account the connector numbering switch, a random check of several connections revealed no differences between the '02/'03 and the '04 ECU pinout. Specifically for the A/F sensor, both signal and heater, the pin numbers are shown as the same whether for B137 on the '02/'03 info or B84 on the '04. The ground distribution info for the '04 turbo ECU shows pins #8 & #9 (black/blue) as ground in the connector that the A/F sensor goes to. I'd suggest checking the voltage at those pins relative to a good chassis ground when doing the other measurements. The voltage there should be very low if there isn't excessive resistance in connectors, etc.

I've got the 03 Forester info already. Foresters are built on the Impreza chassis, so they're similar. However, the WRX is a turbo (2.0L DOHC), and in that respect they're not the same as the base models, and the ECU is different as well.

Yes, I'm aware of that -- what I'd like to know is whether B134 and the other ECU connectors (including B84) shown on page WI-82 (page 3 of the PDF) match your actual ECU (since you said that the B134 diagram I previously posted didn't match). Also, you had previously said that your A/F sensor wiring was to B137. Is that correct, or does it go to what's referred to as B84? I didn't realize that the 3.4 volt reading was taken with the sensor unplugged. I'd suggest the first thing to check is that the white wires you're measuring at the ECU are indeed connected to the A/F sensor. Next, with engine warm and idling, check the voltage on the white wire(s) again, with everything plugged in. The shield should only be connected at the ECU end. Otherwise, it will form a ground loop and likely induce noise rather than shield it. I'm glad to help, and hopefully we'll figure this out. I can understand the "mush" comment. Even though much of my time is spent doing this sort of thing, it still can prove challenging at times. If anyone has a link to a 2003 WRX engine wiring diagram, it would be helpful to be able to compare it to the 2004.

If you were connected to the heavy white wire at the ECU that's going to the A/F sensor heater, it should have read about what you got at the sensor before, about 3.4 volts. Did you have the engine warmed and idling when you got the 3.4 volt reading? Did you have the engine warm and idling when you got the 12 volt reading? Could you check the voltage at the white wires at both the sensor and ECU, engine warm and idling, in order to verify that they're the same? Or, unplug the connector at the sensor and the one you're measuring at the ECU, and check resistance between them to make sure you're on the same wiring.

I didn't expect the B137 to look like it -- only the B134 might have. Please download the following: http://www.ludicrous-speed.com/automotive/impreza/fsm/Impreza-STi-2004/7._Wiring/17._Engine_Electrical_System.Pdf It has diagrams for the 2004 Turbo, SOHC, and STi -- the Turbo is first. See if the ECU connectors match what you have. Let us know.

That should depend on turbo versus non-turbo, etc. -- they vary. So far, I can't find a diagram that matches. 1) Does your B134 ECU connector outline match the diagram I posted? 2) What exact model did the 2004 harness come from -- was it an STi? 3) Can you post a diagram of your B137 (similar to the B134 one I posted)?

Welcome to the forum. Since you didn't mention it, I'll assume that the Check Engine light isn't illuminated (if it is, let us know). One possible cause of the problem you're experiencing is a defective ECTS (Engine Coolant Temperature Sensor). This can fool the ECU into thinking that the engine is warm when it isn't, and not provide a rich enough mixture to allow starting at cold temperatures. The ECU has no way of knowing that the ECTS is misleading it, and doesn't turn on the CEL in this case. You mentioned that the engine was "just overhauled". Did you have the problem before the work was done? Does the engine seem to be cranking at the speed it usually does when it's this cold?

Thanks for the vote of confidence, but I'm no god. This forum has plenty of knowledgeable contributors, of which I'm (hopefully ) sometimes one. Based on "I like to have things to be working correctly and I really like cruise, so I'm going to have to fix it.", I'd suggest you replace whatever is known to be bad (assumedly, the ignition switch). As has already been mentioned, getting the trouble code couldn't hurt. That can usually be done at no charge at major automotive supply stores like AutoZone, Advance, etc. Let us know the what you determine (the Pxxxx code, not the code definition).

The yellow/red wire is the 12v supply to the A/F sensor heater. The "large" (heavier gauge) white one is the ECU control line for the heater. If it's working/connected correctly (pulling towards ground), you should measure under 1.0 volt there. Since it's quite a bit higher, that's what's likely causing the P0031 code to be triggered. Unless someone else knows the answer offhand, this might take a bit of detective work. I have the wiring diagram for the 2004, but not the 2003. The difficulty is that we don't know if there's a wiring difference, or just poor connections leading to a voltage drop. Even if the wiring is correct, high contact resistance could be either in the wiring from the A/F sensor to the ECU, or from the ECU to ground. If you're willing to check a few things, we might be able to figure this out even without the 2003 info. A2 and A3 are pins #2 & #3 of ECU connector B134 (diagram attached). Please verify that heavy gauge white wires are connected there. If so, measure the voltage at those pins relative to a good chassis ground and let us know what you get. You could also wiggle the connections at the sensor and ECU, and see if the voltage at those pins changes (which might require a helper, or long meter leads ).

Like this vacation grouping?: http://www.ludicrous-speed.com/automotive/impreza/fsm/Impreza_2005/

Some 4EAT Phase 2 info: http://endwrench.com/pdf/feb2004pdf/4EATPhase2.pdf That and other 4EAT (Phase 1 and 2) articles can be found at: http://endwrench.com/archive/sysdrive.html

No, that won't trigger a CEL -- the ECU doesn't know it's being "lied to".

I'm the one who's feeling dumb right now. I just reread your first post of this thread, and realized that you have a manual trans. The TCU (Transmission Control Unit) is the computer for an automatic. Sorry, that changes things. The fuel pump relay should be on the same bracket as the main relay, right above it. If we're both looking at the same service manual, try section 2-7, page 32 or so.

P0122 indicates a TPS circuit problem. One possibility is a bad connection at the 20-pin main engine connector, B21 -- the TPS connects to the ECU via three of its pins. You could check that connector for corrosion, etc. It's one of those near the rear of the engine, passenger side. I just read your previous thread. Another thing to check is that the replacement of the pigtail for the TPS was done well. A voltmeter probing at the ECU and someone to wiggle the connections while the meter is read could probably pin down the cause.

You're welcome. You have to pull the lower dash panel, drop the TCU, remove the lower pillar trim, drop the fuse box and remove the bracket. If you don't already have the service manual, get this: http://www.main.experiencetherave.com/subaru_manual_scans/1997_Legacy_FSM/

Yes, there is a fuel pump relay, controlled by the ECU, switching the power to the fuel pump. The ECU and connections directly at it are rarely a problem. Corroded connections elsewhere (especially at the rear) probably occur at least as often as failed pumps. In particular, the ground connection for the pump is a suspect.

I like the engine compartment of my '69 Firebird. Let's clarify the connections. The dimmer on the stalk is a 3-terminal device (potentiometer). I've attached a diagram of the connector that mates with the 83023FA000 Illumination Control Unit/Module. (It's shown from the perspective of the front of the connector, so if you're back-probing with the connector plugged in, the numbering will be "flipped".) The pinout is as follows: 1 - Terminal V3 of the stalk-mounted dimmer (an end terminal) 2 - Lamp control "output" (to all dimmable lamps) 3 - Terminal V1 of the stalk-mounted dimmer (other end terminal) 4 - Terminal V2 of the stalk-mounted dimmer ("wiper" terminal) 5 - 12 volt power in 6 - Ground The above should allow verification of the stalk-mounted dimmer operation. As I mentioned before, make sure there's no short to ground on any of those three leads. If the above doesn't agree with your previous measurements, etc., please let us know.

You're welcome. Please let us know if it works out, when you get a chance.

That explains why you saw 12 volts on both sides of the lamp circuit, as I mentioned above. Although the wire colors you've given don't exactly match the diagram I have, it appears that those three are the ones from the dimmer control on the stalk. You could unplug the module and verify with ohmmeter that the control is functional. There should be a fixed resistance between two of the wires as the control is turned. From either of those two to the remaining one the resistance should vary as the control is turned. Assuming that not "doing anything" means you measured no voltage on any of those three wires, it appears that the module is bad. However, you should probably verify that none of the three wires has an accidental connection to ground.

There's a warning light and switch on the dash for TCS you could check for. If they exist, let me know, and ignore the rest of this post. Otherwise... Luckily, I know where to begin, so there should be more than a glimmer. I suspect that the car doesn't have TCS. There's an ECU pin that's normally grounded through the engine harness when there's no TCS, and the '95 engine probably doesn't have it wired in its harness. The 16-pin bulkhead connector B22 mates to engine connector E3. Take a look at B22 position #16 (diagram attached), and verify there's a wire there. Then look at the what would mate with it on the E3 engine connector. On cars that don't have TCS, position #16 of E3 should have a wire going to ground. If that position is empty on your '95 engine, that's almost certainly why you're getting P1104. If you still have the original engine, take a look at its connector E3, #16, to verify.

John, P1104 is a TCS (Traction Control System) code. So, before we go further, does your '98 OB have TCS?

Try to determine whether there's lack of spark or lack of fuel. Once you know that, we can make further suggestions.