Justin,

To be consistent with the BGB, the title probably should be "Engine ECU Terminals" or something similar. That is what the diagram it is called on page FI-34 of the 1991 BGB.

Besides the addition of PS and PSCT to the USA SW20 GEN2 1991 diagram mention by RickyB, there are other minor discrepancies in the diagrams which do not agree with my version of the BGB. Perhaps the easiest thing would be for me to fax you a copy of that page, since my scanner is not currently working. If you would like me to do that, send me a fax # via email.

Also, it appears that the labels on the 26p, 16p and 22p connector diagrams are reversed, i.e. the JDM are the USDM connectors and vice versa. I say that because the pins on the JDM labeled connectors match the diagram in my BGB and the USDM labled connectors do not.

Mike

 

The JDM ST205 harness does not have an EGR pin. This is only on Euro ST205s. (all this is for non-rally spec ST205s)

Some definitions that might be hard to find:
EVP1 - Evap Canister VSV - use or fake with ~33ohm resistor to ground
CF - Cooling fan, goes to cooling fan relay(s)
THE - Exhaust gas temp switch - can be left open
EGW - Exhaust Gas Warning light output (for gauge cluster)

Those were the 4 wires I had to trace and figure out myself that weren't on the Euro diagrams I bought on CD from Ebay.

Hope that helps a bit.

-Charlie

 

Sensor Descriptions via rickyB:

AFM: this sensor is almost always eliminated when you go to an EMS although some EMS units can use it. It simply runs out of range somewhere between 250-300rwhp of air flow which is the power range most folks switchs to an EMS to begin with.

IAT: the intake air temperature reading is needed only if you use and AFM such as the stock one that measures air velocity instead of air flow. On the gen2 MR2, it is integrated into the AFM, so the two are often thrown away together.

MAP: this sensor becomes the main way of determining engine load when the AFM is removed. The stock gen2 MAP sensor reads up to around 18psi and is often replaced with a true 3 bar MAP sensor with reads up to 30 psi. Some EMS systems come with a built-in MAP sensor while on most others a GM OEM 3 BAR sensor is used. For even higher boost than 30 psi, 5 BAR and even 10 BAR MAP sensors are available from aftermarket suppliers.

MAT: the gen3 engine comes with a MAT sensor in the intake manifold whose operating characteristics are so close to the GM MAT sensor that it can be used on most EMS setups just as it comes. On most gen2 EMS setups, a GM
MAT sensor is inserted into the intake manifold to provide the air density reading needed by the EMS along with the MAP reading to determine engine load.

Crank/Cam: These sensors are housed in the stock distributor base and used by many EMS systems as they are. In some cases, they are replaced with aftermarket sensors and this involves placing a toothed wheel on the crank pulley and in some cases some kind of cam sensor on one of the cams. If you are ok running in batch fire mode, only a crank sensor is required. Perhaps the most popular aftermarket crank trigger is the Electromotive 60-2 tooth setup which yields 5 times the angle resolution of the stock 24 tooth cam wheel.

CTS: the stock coolant temperature sensor is located on the water outlet neck and is nearly electrically identical to the GM coolant temperature sensors. Most EMS system will be able to use this sensor directly.

TPS: the stock TPS is mounted on the side of the throttle body and incorporates a standard potentiometer. I know of no EMS that cannot be calibrated to use the stock TPS. Setups that swap out the stock throttle body in favor of an aftermarket one usually adapt the TPS designed to fit the new throttle body.

SPD: the vehicle speed sensor is located on the speedometer pickup on the back top side of the transmission housing and is similar to the crank sensor except that it is attached to the final output ring of the differential instead of the crankshaft. Every EMS installation that I have seen uses the stock sensor if they read a vehicle speed sensor at all.

KNK: the stock knock sensor is located on the third cylinder area on the back of the engine block beneath the intake manifold. It is a pizzeoelectric microphone tuned to pick up sound frequencies in the 6kHZ range as this is going to be the main component of detonation pings on an 86-87mm bore engine block. All EMSs that can read a knock signal that I am aware of can use the stock knock sensor. In cases where the knock sensor is replaced with another make of sensor, a GM sensor is most often used. This swap is almost always motivated by cost.

EGO: this sensor is a 4-wire narrowband on all USDM motors and is located at the turbo elbow between the turbo outlet and the downpipe. Almost all EMS units that can read a narrowband sensor can use the stock O2 sensor. In some cases, the stock sensor is replaced with an aftermarket universal narrowband sensor primarily because of cost rather than any deficiency in the stock sensor.

WEGO: there is no stock wideband O2 sensor and the only way to get one on the car is to go aftermarket. These are usually 5 wire sensors and all of them require a specialized controller either in the EMS itself or sold as a separate box. Nearly all aftermarket WEGO sensors are based on the popular NTK or Bosch sensors.

EGR: the stock EGR temperature sensor is found only on California cars and located on the side of the EGR pipe. I know of no EMS systems that bother to look at the output of this sensor, but if they do the stock sensor is most likely suitable for the task.

EGT: there is no stock EGT sensor. Those systems that do use and read EGT sensors require that one or more aftermarket thermocouples be plumbed into the exhaust runners.

EBT: the stock setup comes with an engine bay temperature sensor whose signal is not routed to the stock ECU connectors. EMS systems that can read with signal could most probably use the stock sensor with some simple wiring changes as the signal is available at the engine bay fan ECU located beside the main ECU in the trunk.

BATT: All EMS setups read battery voltage directly from their power supply so no external sensor is needed.

BARO: Barometric sensors are not needed except when throttle-based load sensing (alpha-N) via the TPS is used. As this type of load sensing is often inappropriate to use on turbocharged applications, there is no need to add a barometric sensor to the setup. In some cases, EMS systems come with built-in barometric sensors or MAP sensors that can be programmed to become barometric sensors.

OILP: the stock oil pressure sensor is a very simple switch type pressure sensor set to about 3-4psi. If is not even wired into the stock ECU connectors and so it is of little use except for running the stock panel indicator. If you do have an EMS that accepts an oil pressure signal, an aftermarket oil pressure transducer will have to be plumbed into the oil system.

OILT: there is no stock oil temeprature sensor. If you do have an EMS that accepts an oil temperature signal, any standard coolant sensor can be inserted into the oil pan to provide this signal.

OILL: the USDM gen2 engines have a stock oil level sensor whose signal is not available at the ECU connectors and is used only to run a dash warning light. If you do have an EMS that accepts an oil level signal and aftermarket sensor will most likely need to be added to the oil pan (or external reservoir if you have a dry sump system).

FUEL: there is no such sensor on the stock setup. If you do have an EMS that accepts a fuel pressuresignal, an aftermarket fuel pressure sender will have to be plumbed into the fuel system.

 

Another conversion diagram somebody made....

 

Yikes, first thing I notice is that the 1991 posted and the 1993 in my BGB are WAY differnet, I remembered it being just 5 or 6 pins...looks like perhaps 1/3 of them are different?

Second, the one labeled "JDM 1993" in the first post is nearly identical to the one in my US 1993 BGB, the only diffs are B1 is non existant in the JDM (typo as ricky pointed out) and "STJ" is renamed "EVP1"

 

Here is the pinout for the 1993 USDM 3sgte

*edit
And here is one that has both the 91-92 & 93+

 

Thanks, now lets get some experts to tell us what is wrong with the diagrams in the first post!!!

 

Big thanks to mr2man who is helping me get my ideas out on "paper", by editing and hosting my images. I have updated the first post with more accurate modified diagrams!

 

Also, it appears that the labels on the 26p, 16p and 22p connector diagrams are reversed, i.e. the JDM are the USDM connectors and vice versa. I say that because the pins on the JDM labeled connectors match the diagram in my BGB and the USDM labled connectors do not.

The JDM ST205 harness does not have an EGR pin. This is only on Euro ST205s.

Can we get some extra verification on these two facts so that we may upgrade the diagrams to include them?

Thanks :thumbup

 

There are several unhighlited pins on your "conversion" diagram that shouldn't be. For example, T and TE1 are the same thing, it's just that Toyota decided to change the label. You are right that THA and THA1 are the same thing. The same is true of AC and AC1, however. As far as ACT, you can highlight it, but where would it go on a 91? May as well leave it be. The same is also true for OX2 and TE2, you can just let those be.

You are also missing THG in the USDM 91 SW20. It is in the same location as on the USDM 93 SW20. That is another pin you can highlight in the conversion diagram.

You are also missing ABS on the USDM 91 SW20, it is to the right of SPD.

 

Justin,

My comment regarding the 26p,16p and 22p connector diagrams referred to the colored diagrams at the bottom of your original post. They have been edited out of that post, so my comment is no longer relevant.

Mike

 

Cool guys, thank you.

 

There are several unhighlited pins on your "conversion" diagram that shouldn't be. For example, T and TE1 are the same thing, it's just that Toyota decided to change the label. You are right that THA and THA1 are the same thing. The same is true of AC and AC1, however. As far as ACT, you can highlight it, but where would it go on a 91? May as well leave it be. The same is also true for OX2 and TE2, you can just let those be.

You are also missing THG in the USDM 91 SW20. It is in the same location as on the USDM 93 SW20. That is another pin you can highlight in the conversion diagram.

You are also missing ABS on the USDM 91 SW20, it is to the right of SPD.

Thanks for the help Ricky I greatly appreciate it, I fixed what you said there. If there is anything else wrong be sure to let me know.

 

As far as ACT, you can highlight it, but where would it go on a 91? May as well leave it be. The same is also true for OX2 and TE2, you can just let those be.

To clarify:

OX2 = Sub-Oxygen Sensor (OX1 is the main Oxygen Sensor)
TE2 = Labeled "data link connector" - OBD port or something? Need more input on that one
ACT = A/C amplifier [#2]. ACA is AC Amp #1 - why two for 93+?

 

I am just looking at the AEM connection diagram, and for both the 91 & 93 it says for the OX2/TE2pin "Diagnostics...LAMBDA 2.... Avail 02#2 input". So I think that you can just leave that one there. And then for the ACT, it says "Avail, switch intput" so I think that you can just leave that one too.

 

I am just looking at the AEM connection diagram, and for both the 91 & 93 it says for the OX2/TE2pin "Diagnostics...LAMBDA 2.... Avail 02#2 input". So I think that you can just leave that one there. And then for the ACT, it says "Avail, switch intput" so I think that you can just leave that one too.

Cool! So by my count, you have about 15 wires to repin. Please, let us know how it turns out, and if you could take some pics of molex plug disassembly I'm sure that would really help :thumbup

 

What about 1994 usdm n/a to 1992 usdm turbo? Thank you

 

I guess everybody is as clueless with those years as I am...........

 

http://www.mrtwo.net/mr2modproject/gen3stuff/gen3wiringdiagrams/

I've been using this one, ECUpinouts.xls fourth link down on that page.

 

I guess everybody is as clueless with those years as I am...........

Ooohhhh...missed the "N/A" portion Do NOT even attempt this. Get a harness as ricky mentioned!!

 

http://www.mrtwo.net/mr2modproject/gen3stuff/gen3wiringdiagrams/

I've been using this one, ECUpinouts.xls fourth link down on that page.

Nice comparison, thanks!

EDIT: I tried to use that spreadsheet and either I'm misunderstanding it or it has A LOT OF ERRORS.

Users beware!

 

What about 1994 usdm n/a to 1992 usdm turbo? Thank you

The N/A SW21 pin diagrams are completely different. These diagrams apply to the turbo model only. If you are looking to do a conversion, purchase a whole rear clip with intact body harness and swap everything from the body harness back.

 

Cool! So by my count, you have about 15 wires to repin. Please, let us know how it turns out, and if you could take some pics of molex plug disassembly I'm sure that would really help :thumbup

Whoever said it only required 5-6 pins to be moved obviously made the process sound a bit easier than it actually is. Given that many folks have problems even switching one wire around and getting it right, a 91<->93 repin is not for everybody.

 

Whoever said it only required 5-6 pins to be moved obviously made the process sound a bit easier than it actually is. Given that many folks have problems even switching one wire around and getting it right, a 91<->93 repin is not for everybody.

Simply changing a tire or changing one's oil isn't for everybody either. I'd say the difficulty of this is less than that of swapping out a turbo kit. But you're right in that its not for everybody. Be aware of your skill level and be ready to admit when something is over your head.

 

I will be attempting this in the next couple of months, I will probably wait till it gets warmer outside. But my car wiring skills are pretty good, so I am pretty confident that I can do it. I am guessing that it will be a 3 or 4 hour job. But I will keep you guys updated when I do it, and thanks for all the help with the diagrams.