gitee Posted November 22, 2010 Share Posted November 22, 2010 I've got a problem with my '98 LGT where I'm getting accessory power as well as the radiator fan running all the time. I'm getting this with the key out. Also, I'm getting dimly lit warning lights in the instrument cluster, almost like there's some sort of power feedback. From doing a little bit of testing, unless there's a relay that turns on and shuts off the ECM, I'm looking at a bad computer. Anyone know if Subaru's ECMs are interchangeable between the Legacys or Foresters as long as the basics are the same, 2.5L, AWD, Automatic, etc.? Link to comment Share on other sites More sharing options...
idosubaru Posted November 22, 2010 Share Posted November 22, 2010 the differences are minor and you can swap them all day long. doesn't even matter if it's 2.2 or 2.5 liter, they'll interchange as well. of course it's desirable to stay as close as possible since they are likely calibrated for given weights, etc, but i've never noticed a difference personally. up to 1998 is fine and 99 Legacy's are fine. 99 Forester and Impreza RS will not work. 99 EJ22's won't work. Any other 99's or earlier will. clear as mud? i have an ECU that's a great match for you. Sedan, 2.5 liter, automatic, DOHC, Legacy LSi. PM or email me and we'll deal. that being said - i would guess this is something other than the ECU causing this. Link to comment Share on other sites More sharing options...
gitee Posted November 22, 2010 Author Share Posted November 22, 2010 grossgary, thanks for the info! Yeah, I'm trying to find anything I can to rule out the ECM, but I don't know where else to look. Any ideas? Disconnecting the battery will shut off the fan/accessories, as well as disconnecting the ECM. After cycling the key, the fan/accessories have power even after removing the key. I tried following the main relay and if I read the wiring diagram correctly, there's a light green wire which energizes it. Wiring diagram shows that this light green wire is #63 pin for the ECM which is verified as having power there as well. Any idea of what powers the ECM? Or am I going at it the wrong way? Link to comment Share on other sites More sharing options...
zacyork Posted November 22, 2010 Share Posted November 22, 2010 could be your main relay is stuck open. get a test light on the power wire exititing the relay and see if there is power with key off. Link to comment Share on other sites More sharing options...
gitee Posted November 22, 2010 Author Share Posted November 22, 2010 Tested the main relay with the power off. No power coming out. I initially was going to go after the relay, but after thinking about it, with power tested at the light green wire (energizes the relay), I kind of ruled it out. If the relay were stuck, wouldn't the energizing wire have no power? Link to comment Share on other sites More sharing options...
idosubaru Posted November 22, 2010 Share Posted November 22, 2010 relay would seem a likely failure point. is the fan triggered by a coolant temp sensor or is it toggled on directly by the ECU? i haven't run across this in newer gen stuff. does that fan come on with the A/C as well, is that another area to check - another relay for that? Link to comment Share on other sites More sharing options...
zacyork Posted November 22, 2010 Share Posted November 22, 2010 if the relay was stuck on it would not need the energizing wire. it would be like bridging the relay from power in to power out. the energizing wire would only have power with key on. no matter what the relay is doing. Link to comment Share on other sites More sharing options...
johnceggleston Posted November 22, 2010 Share Posted November 22, 2010 any other work done recently.?? i disconnected the 3 connectors at the rear of the engine, 2 large, 1 smaller to ''clean'' the contacts. left them undone to dry and addressed something else inside the car. a few minutes later i went to start it and of course, nothing. but when i turned the key off to remove it, the fans started running continuously, and other weird stuff. so i remembered the connectors and plugged them back in. only when i connected the 3rd one, the bottom most one, did the fans go off. and then when i tried the key it started right up. thank goodness. good luck. Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 22, 2010 Share Posted November 22, 2010 Do all of your signal/brake light bulbs work? A common point for feedback is through dual filament bulbs where one filament breaks and falls across the other one. Try pulling fuses/relays until you find which circuits have the draw. Link to comment Share on other sites More sharing options...
gitee Posted November 22, 2010 Author Share Posted November 22, 2010 if the relay was stuck on it would not need the energizing wire. it would be like bridging the relay from power in to power out. the energizing wire would only have power with key on. no matter what the relay is doing. Correct. This is what lead me to believe the problem isn't the relay, as the energizing wire has power even with the key out. Link to comment Share on other sites More sharing options...
gitee Posted November 22, 2010 Author Share Posted November 22, 2010 any other work done recently.?? i disconnected the 3 connectors at the rear of the engine, 2 large, 1 smaller to ''clean'' the contacts. left them undone to dry and addressed something else inside the car. a few minutes later i went to start it and of course, nothing. but when i turned the key off to remove it, the fans started running continuously, and other weird stuff. so i remembered the connectors and plugged them back in. only when i connected the 3rd one, the bottom most one, did the fans go off. and then when i tried the key it started right up. thank goodness. good luck. Are these 3 connectors the 3 on the passenger side underneath the air intake, close to the transmission? I haven't done any work to it, but the guy who owned it before me had the head gaskets done about 120 miles ago. Link to comment Share on other sites More sharing options...
zacyork Posted November 22, 2010 Share Posted November 22, 2010 it could be other relays or fuses giving you problems. cover your butt and check them before you say its the ecu. thats usually the last thing you want to condone. Link to comment Share on other sites More sharing options...
gitee Posted November 22, 2010 Author Share Posted November 22, 2010 Do all of your signal/brake light bulbs work? A common point for feedback is through dual filament bulbs where one filament breaks and falls across the other one. Try pulling fuses/relays until you find which circuits have the draw. Hmm, haven't looked into this. Would the signal/brake light bulbs need to be on in order to create the feedback? Link to comment Share on other sites More sharing options...
gitee Posted November 22, 2010 Author Share Posted November 22, 2010 it could be other relays or fuses giving you problems. cover your butt and check them before you say its the ecu. thats usually the last thing you want to condone. Yep, that's why I'm asking here to get some ideas. Link to comment Share on other sites More sharing options...
johnceggleston Posted November 22, 2010 Share Posted November 22, 2010 Are these 3 connectors the 3 on the passenger side underneath the air intake, close to the transmission? I haven't done any work to it, but the guy who owned it before me had the head gaskets done about 120 miles ago. yes those are the 3. Link to comment Share on other sites More sharing options...
gitee Posted November 22, 2010 Author Share Posted November 22, 2010 yes those are the 3. I actually unplugged these while the fan was running and the fan started blowing even faster. Unplugging those 3 basically just took a load off of the shorted circuit. Link to comment Share on other sites More sharing options...
gitee Posted November 22, 2010 Author Share Posted November 22, 2010 I should clarify what stays on/has power while the key is out. Passenger side radiator fan, power windows, blower motor, and some dimly lit warning lights in the instrument cluster. Link to comment Share on other sites More sharing options...
idosubaru Posted November 22, 2010 Share Posted November 22, 2010 a glance at an FSM to see what fuses and fusible links are related to these circuits would probably narrow this down for you. Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 22, 2010 Share Posted November 22, 2010 (edited) a glance at an FSM to see what fuses and fusible links are related to these circuits would probably narrow this down for you. I just had the same idea and took a look at the 99 FSM (don't have 98). FB-4 Engine control module Fuel pump relay Ignition coil Transmission control module FB-17 Rear defogger timer FB-18 AT shift lock control module Back-up light switch (MT) Inhibitor switch (AT) FB-19 Hazard switch FB-20 A/C switch Combination meter Mode control panel Rear defogger timer TCS off switch FB-22 Blower motor relay Check connector Daytime running light control module Daytime running light relay FRESH/RECIRC actuator Hi-beam relay Keyless entry control module Power window and sunroof relay Seat belt timer Security control module Vehicle speed sensor (MT) Wiper deicer relay Wiper deicer timer FB-23 Airbag control module FB-24 Airbag control module FB-25 Lighting switch IG Headlight alarm relay All of these draw power from the ignition switch. So the question is... is the ignition switch out of adjustment or faulty and allowing a small amount of current through when it's in the off position? Or is power back-feeding from one of the sources listed? Lots of options there. Of course this is all for 99 so 98 may be a bit different. You can narrow it down by pulling fuses for these in the interior fuse panel under the dash. Hmm, haven't looked into this. Would the signal/brake light bulbs need to be on in order to create the feedback? Depends on the type of circuit. Some makers switch the ground side of the light circuit. So any short to ground in the circuit between the lights and the switch would make the lights stay on. Edited November 22, 2010 by Fairtax4me Link to comment Share on other sites More sharing options...
gitee Posted November 23, 2010 Author Share Posted November 23, 2010 Ok. I'm a noob to Subies, so bear with me. I thought this at first too, but I think I ruled out the ignition switch. With the fan on, etc, I unplugged the switch from the harness and everything was still running. Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 23, 2010 Share Posted November 23, 2010 Perfect! In that case, you probably have a backfeed from elsewhere. Now you just have to track it down. Easier said than done sometimes. But as I said before, start pulling fuses to see if you can isolate the problem circuit. Even if you can't get it narrowed down to one, you can at least get an idea of where the power is coming from. Lets say you pull one fuse and one of your problem areas turns off (say the blower fan) but the rest stay on, you can rule out anything powered by that fuse for being the source of the back feed. You can also pull all of the fuses one at a time and check the outgoing sides of each for voltage. Obviously you should only have 12v on one side the other should be 0. If you find voltage you can check each leg of the harness from that fuse. Link to comment Share on other sites More sharing options...
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