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G3.Spiffy

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About G3.Spiffy

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  • Location
    Santa Cruz California
  • Referral
    Mutual Subaru Enthusiast
  • Biography
    Currently working to complete an engine swap in a 1986 Subaru GL wagon which was originally carbed. Donor parts are from a 1988 GL10 wagon which received an SPFI engine swap from an unknown year.
  • Vehicles
    1986 GL Wagon with 1988(?) SPFI Swap
  1. G3.Spiffy

    ECU Light Stays On

    Much appreciated, good luck on your projects as well!
  2. G3.Spiffy

    ECU Light Stays On

    Exactly what I was thinking, but I’ve checked all power into the ECU from the ignition switch and it has power in where it should when it should according to the FSM diagrams. If it didn’t know it was running, the car wouldn’t actually run because it needs the ECU to control its functions right? I’m not sure how to go about tracking down what input could be missing aside form checking FSM diagrams, using a multimeter, and tracing wires. Which I feel I’ve done to the best of my ability. Any suggestions?
  3. G3.Spiffy

    ECU Light Stays On

    So, after finding out that all three of my ECUs are interchangeable, I put the one which I believed had the damaged transistor into the 92, and checked the function of things. Absolutely everything works... including the CEl... The good news is that my ECU is fine, but the bad news is I still have something going on which is preventing the CEL from functioning in the car I’m working on. After making this discovery I reinstalled the ECU in the car with the issue and got to work tracing things for what feels like the thousandth time. I absolutely, 100% have the two wires hooked up to the proper locations (one to 12v power and one to pin 2 of the ECU. I’ve swapped multiple bulbs which I know work with no change. The voltage gets all the way from the IG key position, through the bulb, and all the way to pin 2. Is the ECU not what grounds the CEL to check function before the engine is started? This is the only thing that really makes sense to me, but maybe someone else can help out.
  4. Thank you, this saves me a lot of headaches. I didn’t know I needed to search them on a Subaru website. Hope this is able to help others as well!
  5. I have three different spfi manual trans wagons, all are stage 2 (post wiring changes) and I need to know if the ECUs can be swapped around between them. Pictured are the ECUs in question. All have different numbering on the stickers. After some extensive searching I’ve been unable to find a thread which answers my questions. Links to threads which I may have missed are appreciated!
  6. G3.Spiffy

    ECU Light Stays On

    All of the cars are manual so theoretically I wouldn’t have to rewire anything, it would just be plug and play right? What are the chances that I could damage something if I throw the problematic ECU into the 92? This would allow me to test for function and interchangeability before installing a good ECU into a car that could still have something shorting out that circuit and see if it runs everything but the CEL in the 92. If the ECUs are the same, and I know for sure I’ve fixed whatever damaged the original ECU, I’ll probably just use the one with the good CEL just for my emissions test, then switch back because the 92 is all original and I’d like to keep all of its parts together until that’s no longer possible.
  7. G3.Spiffy

    ECU Light Stays On

    It seems highly likely this is what I did. Any advice on how to replace the transistor/IC chip? Or is the ECU no longer viable? If so, I have two other ECUs which are from a 90 and a 92 Loyale spfi manual trans. The systems that they run seem pretty close to identical but the sticker on the housings all have different numbers. Any info on spfi manual trans ECU interchangeably?
  8. G3.Spiffy

    ECU Light Stays On

    So if I understand what you’re saying (correct me if I’m wrong), it’s possibly normal for me to get the 5v reading mentioned earlier when the bulb is out (open circuit) depending on how the inside of the ecu is configured. If that’s the case can I visually observe this inside the ecu? Or would that be a part of an IC chip? Speaking in terms of the function of the CEL, the wire that exits the ECU and goes to the signal side of the CEL should be connected to ground whenever this transistor flips its switch, correct? If I understand what’s going on, there is something preventing the ECU from flipping that switch. This could be: •The switch is damaged and can’t function. •The ECU doesn’t know to turn on the CEL to test function with the key in IG and the engine off. This could be because of some other damaged internal ECU component or due to bad connections upstream. I’ve checked all connections outside of the ECU pretty extensively and am pretty confident my issue lies somewhere inside the ECU. What I need now is to diagnose what actually failed and figure out a course of action to fix it or replace the unit if necessary. I’m located in CA so I need the CEL to function to pass emissions unfortunately. Thank you for the input!
  9. G3.Spiffy

    ECU Light Stays On

    Yes, those were the other lights I was referring to. That makes a lot of sense, and is sort of what I got to as well. For whatever reason the ecu isn’t giving the signal to ground the connection. Based on this I uninstalled and opened up the ecu to inspect for burnt components or corrosion, which I found none of. The ecu is spotless inside. Is there any course of action from here? Can I track things farther somehow and make a repair if needed or do I have to pay some professional who probably doesn’t know what they’re doing to repair the ecu? I haven’t looked at the part number yet but I may have a spare ecu that I could swap in to see if that fixes things but if there’s some power issue still present in the car I’m concerned about damaging the second unit as well.
  10. G3.Spiffy

    ECU Light Stays On

    Could I have fried the IC chip related to the CEL?
  11. G3.Spiffy

    ECU Light Stays On

    I tested the other bulbs the same way, and all of them get the same reading on the IG side as they should, but two of them have ~2.5v on the other side and one has ~145mv. Those are the ones that work, so it’s weird that they don’t all read the same on the other side as well. That being said, the one that only has ~145mv is brighter than the other two working ones. Don’t know what to think of that
  12. G3.Spiffy

    ECU Light Stays On

    With a known good bulb in and it closed-circuit, there is still ~12v on the IG side but more like 10.5 on the other side. Is this normal? I’ll throw a different bulb in just in case, but did make the current one light up by opening the circuit and applying ground to the non 12v side of the circuit
  13. G3.Spiffy

    ECU Light Stays On

    After some extensive poking around I’ve determined that the only thing not working as it should is the CEL. The fuel pump “issue” was just test mode probing the fuel pump. The light on the ECU acts as it should in each test mode or read memory mode configuration, but I can’t get the CEL to come on for the life of me. If I take the bulb out and test the voltage on the circuit board, there is ~12v on the IG power side, and 5.something volts on the other side coming from the ECU. Same thing if I probe the proper pin at the ECU. I feel like this 5v signal from the ECU should function as a ground to turn on the CEL seeing as how it has power on the other side. Should my ECU be sending 5v out to the CEL? If not, what could cause this and what can I check to try and fix it? I’ve checked all my power going into the ECU and cleaned all the grounds which are associated.
  14. G3.Spiffy

    ECU Light Stays On

    Test connectors are unplugged Yea looks like you’re right. It seems like I have something funky going on electrically. I was poking around under the dash today double checking things and suddenly my fuel pump primed and was pushing fuel back into the tank. It only stopped when I jostled things around a bit so it looks like I have exposed metal making connections it shouldn’t somewhere... or maybe managed to damage my ecu somehow? The car still runs fine though so I doubt that. I’m leaning towards bad connection or I made an error when getting power to things. I had everything working just before this happened and have everything else working still, except the CEL, weird fuel pump issue, and light on the ecu.
  15. G3.Spiffy

    ECU Light Stays On

    So could it just be due to the engine being cold when I checked it while running? It wasn’t on long enough to heat up
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