ECU Info for '93 SC400
07-05-12, 08:27 PM
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ECU Info for '93 SC400
Hey guys, new to the site here and in desperate need of help.. 
I've got a '93 SC400 that I'm assuming has some ECU issues like the rest of em.. I did remove and inspect the unit and sure enough two capacitors were bad. I replaced them, reinstalled ECU, turned ignition on and no CEL came on. Cranked the car and it ran for about ten seconds and fell on it's face. I've replaced fuel filter, fuel pump, fuel pump control module, and bad capicitors in the ECU.
I'm trying to figure out which wires i need to test for source voltage and ground for the ECU. Yes, I've called toyota and it seems nobody can help. Any suggestions or schematics would be awesome. Thanks for reading.
I've got a '93 SC400 that I'm assuming has some ECU issues like the rest of em.. I did remove and inspect the unit and sure enough two capacitors were bad. I replaced them, reinstalled ECU, turned ignition on and no CEL came on. Cranked the car and it ran for about ten seconds and fell on it's face. I've replaced fuel filter, fuel pump, fuel pump control module, and bad capicitors in the ECU.I'm trying to figure out which wires i need to test for source voltage and ground for the ECU. Yes, I've called toyota and it seems nobody can help. Any suggestions or schematics would be awesome. Thanks for reading.
07-06-12, 12:49 PM
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Typically, no CEL at all points to a bad ECU. Have you tried swapping it out for another one to see if your symptoms change?
Main power to the ECU is pin 31 and 32 on the 40-pin ECU connector (the one without the bolt through it)
ECU grounds are at pins 4, 69, 79, and 80 on the 80-pin ECU connector (the one WITH the bolt through it) You also have a sensor ground (ground provided by the ECU for certain sensors) at pin 65 on the 80-pin. You should NOT have continuity to the chassis at pin 65, but should at the other 4 pins.
Main power to the ECU is pin 31 and 32 on the 40-pin ECU connector (the one without the bolt through it)
ECU grounds are at pins 4, 69, 79, and 80 on the 80-pin ECU connector (the one WITH the bolt through it) You also have a sensor ground (ground provided by the ECU for certain sensors) at pin 65 on the 80-pin. You should NOT have continuity to the chassis at pin 65, but should at the other 4 pins.
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1993, 1993 sc400, 93, bad, capacitor, capacitors, change, computer, ecu, ecu problem, guam, lexus, replace, replacement, sc400, symptoms
