ECU Grounds... Where are they?

btwilson86 · 05-28-2007, 04:42 AM

So... I have a code 11 when I run diagnostics (disrupted power to ECU). I'm told that it's most likely a bad ground or short somewhere, as the car still runs fine. I found somewhere on this forum the pin out diagram for the ECU on a 1990 N/A Auto tranny. I have a 87 N/A Auto, so I'm wondering if the grounds between the two ECU's are the same. Anyone know? Cuz I heard that in 89 or something they added a sensor that detects a high altitude to adjust the air/fuel mixture, and I'm hoping that Toyota just utilized an unused pin on the ECU.

I've also been told that the housing on ECU's in some later model Toyotas are the computer ground, and that just bolts to the frame to get grounded....

It's all kind of giving me a headache, and I don't particularly want to ruin my ECU by grounding a wire that shouldn't be grounded, so if anyone has any ideas, it'd be very much appreciated.

cre · 05-28-2007, 06:26 AM

E01 and E02 apparently connected to Ground Point B.

http://www.cygnusx1.net/Supra/Librar...=Main&Page=148
http://www.cygnusx1.net/Supra/Librar...n=Main&Page=26

This is the Pinout for the '89 N/A There are a couple additional connections that aren't present or used on the pre89 models. The pinout for power and ground point is accurate though.
http://www.cygnusx1.net/Supra/Librar...ion=FI&Page=31

btwilson86 · 05-28-2007, 04:49 PM

Ok, cool. Those diagrams should help out alot.

btwilson86 · 05-29-2007, 06:24 AM

Thanks again for those diagrams. Turns out one of my ground wires were frayed a little, and it wasn't a very good ground for the ECU. So now I got the real trouble codes I need to finally get rid of that dang check engine light; 51 and 52.

cre · 05-29-2007, 09:16 AM

IIRC, code 51 will throw from moving the throttle while the diagnostic jumpers are in place or if the TPS is misaligned so the idle switch isn't engaged.

52 is the knock sensor circuit.

j3pz · 05-29-2007, 09:36 PM

same 51 and 52
http://www.toyota-supra.info/forums/...=rewire+sensor

05-28-2007, 04:42 AM	#1
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	ECU Grounds... Where are they? So... I have a code 11 when I run diagnostics (disrupted power to ECU). I'm told that it's most likely a bad ground or short somewhere, as the car still runs fine. I found somewhere on this forum the pin out diagram for the ECU on a 1990 N/A Auto tranny. I have a 87 N/A Auto, so I'm wondering if the grounds between the two ECU's are the same. Anyone know? Cuz I heard that in 89 or something they added a sensor that detects a high altitude to adjust the air/fuel mixture, and I'm hoping that Toyota just utilized an unused pin on the ECU. I've also been told that the housing on ECU's in some later model Toyotas are the computer ground, and that just bolts to the frame to get grounded.... It's all kind of giving me a headache, and I don't particularly want to ruin my ECU by grounding a wire that shouldn't be grounded, so if anyone has any ideas, it'd be very much appreciated. __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

05-28-2007, 04:49 PM	#3
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	Ok, cool. Those diagrams should help out alot. __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

05-29-2007, 06:24 AM	#4
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	Thanks again for those diagrams. Turns out one of my ground wires were frayed a little, and it wasn't a very good ground for the ECU. So now I got the real trouble codes I need to finally get rid of that dang check engine light; 51 and 52. __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

05-29-2007, 09:36 PM	#6
j3pz 500whp yet? Join Date: Nov 2005 Location: Mechanicsville, MD, US of A, 20659 Posts: 1,060	same 51 and 52 http://www.toyota-supra.info/forums/...=rewire+sensor __________________ 88 N/A w/ 5spd - stock - not running, bhg 87 turbo/targa w/ 5spd- fidanza light weight flywheel, new oem slave cylinder, apexi air filter, no ac and no heat

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05-28-2007, 06:26 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	E01 and E02 apparently connected to Ground Point B. http://www.cygnusx1.net/Supra/Librar...=Main&Page=148 http://www.cygnusx1.net/Supra/Librar...n=Main&Page=26 This is the Pinout for the '89 N/A There are a couple additional connections that aren't present or used on the pre89 models. The pinout for power and ground point is accurate though. http://www.cygnusx1.net/Supra/Librar...ion=FI&Page=31

05-29-2007, 09:16 AM	#5
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	IIRC, code 51 will throw from moving the throttle while the diagnostic jumpers are in place or if the TPS is misaligned so the idle switch isn't engaged. 52 is the knock sensor circuit.