GeneralDisorder Posted May 4, 2006 Share Posted May 4, 2006 Ok - so I'm in the process or convering the Brat's EA81 to EA82 SPFI. I've got all the electrical worked out save for the speed sensor. Well - I have the wire for the ECU, and I have a yellow/red wire from the cluster that the EA81 FSM indicates is the speed sensor. The EA81's were equipped with this for the optional cruise control unit. My question is does it operate the same as the EA82 speed sensor and will the signal be compatible with the Loyale SPFI ECU? Here's what I could find to describe the EA81 speed sensor operation from my 84 FSM: "When the speedometer cable rotates with the ignition-starter switch on, on-off signals at more than 5V and 0V are repeatedly transmitted." Does this coincide with the EA82 speed sensor design? GD Quote Link to comment Share on other sites More sharing options...
msteel Posted May 4, 2006 Share Posted May 4, 2006 Well, I'm not one of the Subaru experts, but its been, what, a couple of hours? So I'll give it a go. According to the schematics I have (Chiltons, I don't have a FSM, so trust them how you will) the vehicle speed sensor in a Loyale SPFI looks like a reed switch. So I would be fairly certain that it would give an on-off signal at a rate dependent on vehicle speed. The next issue is voltage level. Probably the sensor pulses at a nominal 12 volts. I would not be at all surprised if the threshold the ECU used to determine on from off were 5v, since that is pretty much the standard level for computer logic. What is less certain is whether the pulse rate would be the same between EA81 and EA82. For example, 60mph might be 60 pulses per second on one and 30 pulses per second on the other. Which brings up the question of whether it would matter. I remember reading here that the ECU uses the VSS signal very little on manual transmision cars. So in short, I'll give you a resounding "Probably" (Just what you were looking for;) ) Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted May 4, 2006 Author Share Posted May 4, 2006 Yeah - I just don't want the ECU to give off an error code by not having it connected. I'm connecting the ECS light in the dash as well, and I would like the ECU to report correctly. So sounds like it's most likely the same... I just don't want to blow up the ECU with a weird signal at some enormous voltage. GD Quote Link to comment Share on other sites More sharing options...
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