Dustin70 Posted July 25, 2011 Share Posted July 25, 2011 Hey everyone, I'm the proud owner of a 91 legacy wagon, non turbo, front wheel drive, automatic. I've got a persistent check engine light with a code for atmospheric pressure sensor. As I understand it, this sensor is part of the ecu... am I right? Anyway, if this is right, does anyone have a part number that I can use to search ebay? Or one to sell? Thanks. Quote Link to comment Share on other sites More sharing options...
Dustin70 Posted July 25, 2011 Author Share Posted July 25, 2011 Oh, and if you know what year cars will swap? Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted July 25, 2011 Share Posted July 25, 2011 I've got a persistent check engine light with a code for atmospheric pressure sensor. isn't this is a MAP sensor? not part of the ECU? so you do not need a computer. 90 - 94 should swap in no problem, i think. but i would check you wire connections and vac lines under the hood first. it could be a bad hose. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 25, 2011 Share Posted July 25, 2011 I beleive the MAP is actually part of the TCU's assortment of sensors and it's input is then also routed to the ECU..... the ECU itself has no MAP sensor that is external so if it's not the one on the passenger side strut tower then the ECU must have an internal MAP that is bad. Though I have never seen nor heard of this happening before. GD Quote Link to comment Share on other sites More sharing options...
Dustin70 Posted July 26, 2011 Author Share Posted July 26, 2011 According to my Mitchell manual at work, there is no MAP... so I need the computer. Do you know any part numbers? When I search ebay for "91 subaru legacy ecu" I get listings for cars not necessarily legacies and years through the late 90's... I'm pretty sure these won't all work, right? Quote Link to comment Share on other sites More sharing options...
heartless Posted July 26, 2011 Share Posted July 26, 2011 According to my Mitchell manual at work, there is no MAP... so I need the computer. Do you know any part numbers? When I search ebay for "91 subaru legacy ecu" I get listings for cars not necessarily legacies and years through the late 90's... I'm pretty sure these won't all work, right? according to my 1990 FSM - this is a correct diagnosis. "Trouble code 45: Atmospheric Pressure Sensor When trouble code 45 appears on display, replace ECU" I would think that any FWD automatic ECU from 90-94 should take care of it for you. sorry i cant give you an exact part number, my car is an AWD... Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 26, 2011 Share Posted July 26, 2011 (edited) Any 90 through 94 *Legacy* (Not Loyale's) ECU will work. AWD/FWD and automatic/manual don't matter. The ECU doesn't care about the former, and the latter is determined by a ground pin on the harness not by the ECU itself. If it were me I would open the ECU up and see if it's just a bad trace or solder joint or obviously burnt transistor/cap. The Japanese solder tends to corrode and shrink over time and that is the biggest cause of electronics failure among Subaru's, Honda's and Toyota's. Mitsubishi just uses junk caps that leak and burst all over their boards..... lowest bidder components GD Edited July 26, 2011 by GeneralDisorder Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted July 26, 2011 Share Posted July 26, 2011 item #1 in the drawing. http://opposedforces.com/parts/legacy/us_b11/type_3/engine_electronic/relay_and_sensor_engine/ Quote Link to comment Share on other sites More sharing options...
Dustin70 Posted July 26, 2011 Author Share Posted July 26, 2011 Cool... thanks for the responses everyone. Quote Link to comment Share on other sites More sharing options...
wtdash Posted July 26, 2011 Share Posted July 26, 2011 (edited) Hi, Legacy Central has the ECU pinout HERE. It shows a "barometric pressure sensor" for the '90-92 models only. As already noted, I'm 99% sure I read this is internal to the ECU...can't find it now. The '92-94 ECUs should work, but I believe your '91 TCU may be looking for the ECU's sensor from the '90-91...not sure if it'll throw a code - flashing 'power' light'. This POST has a link to pics of the FSM's TCU pinout w/the 'atmospheric sensor' in the TCU. Td Edited July 26, 2011 by wtdash Quote Link to comment Share on other sites More sharing options...
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