MR2 Owners Club Forum banner
1 - 19 of 19 Posts

·
Super Moderator
Joined
·
3,474 Posts
It’s been many years since I’ve been on here as my 91T has been collecting dust in my garage…I’ve finally come into some time to get back into it but I need some help identifying some plugs on the engine harness. It’s a 91T chassis with a JDM 3rd gen 3sgte in it and I know some of the plugs don’t get used but I can’t remember which ones these are…also the 2 wires for my fuel pump resistor solenoid pulled out of the harness side and I don’t know which way they go back in…please help…
55 = Distributor
56 = Coil
DC = Igniter
29 = Not 100% sure.
E1 = Pin 1 is Blue w/White. Pin 2 is Blue w/Black. In the photos they are set up correctly, not that it really matters as it is a resistor so can be wired either way.
 

·
Super Moderator
Joined
·
3,474 Posts
Also need help identifying these 2 wires. Engine bay fuse box 1 is black with a white stripe and 1 is solid blue…I can’t even find them in the BGB…please help!
The Black w/White wire is for the AC magnetic clutch.
The Blue wire is for the Cooling Fan motor power.
 

·
Super Moderator
Joined
·
3,474 Posts
Thanks, I got it running this afternoon finally…but my tach is not working so I’ll be chasing wires for a bit longer
The Tach wire is black. In pin 5 of the plug called EA3. The one I circled. It takes a signal off the igniter.
So it goes, Pin 4 Igniter, Pin 5 EA3, runs through the body harness down the left side of the car to plug IE1 in the left kick panel. Then it heads off to the gauges. Make sure all those connections are good and the wires are good and it should work unless the gauge isn't happy.
Electrical wiring Cable Electronic engineering Auto part Electronic device
 

·
Super Moderator
Joined
·
3,474 Posts
Interesting. But you aren't blowing a fuse?
I assume you've done your checks of the wire? The black wire is sort of hiding in your photo but it appears correct in the fuse box plug. Toyota didn't really change the wiring in this plug apart from the air temp sensor and some AC idle up stuff depending on the model. The tacho stayed the same except for maybe the BEAMS 3SGE version which could still be in that location knowing Toyota.
 

·
Super Moderator
Joined
·
3,474 Posts
Ok. Lets figure this out.

I'm going to list as many wires as I can that go to the 7.5A GAUGE fuse and then we can check on your car if it is right vs the engine harness.

91 SW20 USDM wiring diagram
Page 72 Cooling Fan Warning light.
Page 55 Check Engine Light
Page 56 Potentially the ELS diode
Possibly more, I ran out of time to look.

Looking at the ecu connections and I can’t seem to match them up with any diagrams that I’ve found…does this look like it should? I have wires in places that are marked as empty 😳…Does someone have the correct pin out
Open up the ECU. The pinout is written on the board.
Also what is the pink wire coming out of the EA1 plug-labeled “CCo” in the diagnostic port?
CCo is Catalytic converter temp sensor.
 

·
Super Moderator
Joined
·
3,474 Posts
Font Audio equipment Office supplies Office equipment Electronic device


The text at each pin on he socket. RSC and RSO for idle control as an example.

1. Idle speedo control valve or ISCV.
2. IAT or Intake Air Temperature Sensor
3. Boost control solenoid or T-VSV. (Not TVIS)
The temp sensor is only there to note when your cat is getting too hot, I've cut mine off the GEN2 3SGE and no affects.
 

·
Super Moderator
Joined
·
3,474 Posts
Awesome thanks!…still trying to untangle the rats nest so I can be sure there are no shorts and everything is connected that needs to be. I’m also going to redo all of the common grounds because they’re all tangled throughout the harness and I’m getting sick of pulling pins to reroute wires…I’m going to have gray hair from this
Yeah the Toyota way of building these harnesses with the grounding wires all over the place is crazy. Nothing is simple.
 

·
Super Moderator
Joined
·
3,474 Posts
Here’s what my 16 pin looks like:

What are these abbreviations?
VISC
INT
MTT
EVP1
M+
EVP2
M-
THAM
THAM is air intake temp sensor manifold
I don't know what the rest are.
Ok had to take some time off from car stuff but back at it now…redid all of the grounds from engine harness, black wire(AC magnetic clutch) has voltage with ignition on…7.5 fuse blows as soon as ignition is set to on position, tach does not sweep when ignition is turned on(same fuse)…
The tach will not sweep. This is a 30 year old car, they never did that.
You need to unplug ALL of the items I listed and determine if the fuse is blowing with them unplugged. Then plug them in one by one to find which one blows the fuse if it doesn't immediately.
What are the pages you’re referring to for this? Do I need to pull the cluster to get to these connections? I traced only 1 wire from the kick panel fuse box for this fuse, but it went under the dashbut I couldn’t trace it very far before it was lost in the nest…
I am using the electronic PDF 1993 USDM SW20 MR2 wiring diagram document.
To get to those connectors, yes you need to pull the cluster but that's not hard.
 

·
Super Moderator
Joined
·
3,474 Posts
Just discovered that it’s connected to 2 under the fuse box: white w/black stripe and red…?
That is not normal. The red wire is not meant to be connected to that. The heat shrink is not OEM. They never used that, it was just tape.

The coolant temp gauge does ground to the engine. Can you determine where that red wire goes?
Red is normally the Starter relay wire but I can't tell if it's just been added in.
 

·
Super Moderator
Joined
·
3,474 Posts
Could be this…?
It definitely could be that. If that's for the oil level light then it's not needed. And if it's blowing the fuse then definitely don't have it connected.

What do you mean continuity? You mean the wires are connected between the gauges and the kick panel around IE3 area?
 

·
Super Moderator
Joined
·
3,474 Posts
Couldn’t find a jumper connection that would blow the fuse in the cluster…checked the code as per BGB and it’s throwing a 21 which is oxygen sensor/o2 sensor heating circuit…
That code can show up if the engine is cold.
Can you unplug the sensor and see if the fuse blows?

So where are we at? Are you still getting the fuse blowing?
Have you unplugged all the items I listed and then plugged them in one by one to see what blows the fuse?
 

·
Super Moderator
Joined
·
3,474 Posts
Ok cool.

Shouldn't the battery light come on with the key in the ON position anyway?
The check engine light should also be on too until the engine starts. Same for the low oil pressure light. That red wire you disconnected seems to be the root cause of the issues. It is not supposed to be connected like it was. No idea what brought the previous owner to do that.
 

·
Super Moderator
Joined
·
3,474 Posts
That would definitely explain the short run time with the resistor relay not being connected. The ECU runs 12v at start up and then back to 5V until you get on boost.

Ok so now I understand someone has gone through and made the harness for you. Only some minor things were changed but the red wire being joint up I think was to stop the oil level light going on. You don't need this as the JDM GEN3 3SGTE does not have an oil level sensor. If you get it running, ignore that light until you can remove it from the dashboard.
 

·
Super Moderator
Joined
·
3,474 Posts
That’s what I was thinking too except that it’s the oil pressure light, not the oil level light. I’m going see if it’ll start and run up to operating temp this weekend, then I’ll check to see if it’s throwing and codes again.
The red wire seems to be the oil level light but the wire it was connected to is the oil pressure switch light.
Let me know how you get on.
 

·
Super Moderator
Joined
·
3,474 Posts
Just to see what would happen:!this morning I unplugged the oil pressure sensor and turned the ignition on and the low oil pressure light did not come on…plugged it back in and the light came on. I wonder if the sensor is bad?
This is how it is meant to operate. The switch is spring loaded so when it has no oil pressure it closes and grounds through the engine completing the circuit turning on the light. When oil pressure is applied it pushes the switch open and the circuit is broken and the light turns off. It is on or off, no actual pressure readings will ever come from this sensor.
 

·
Super Moderator
Joined
·
3,474 Posts
Also discovered that my A/C pressure switch being disconnected is the reason that my radiator fans are on constantly…if I run a jumper wire there will the fans still turn on if it gets too hot?
…still working on the tach
The jumper connector is standard on the cars without AC. That should stop them running when not needed. Although can you confirm that both are running?
There are 2 fans in the front. One for AC, the other for the engine radiator. I'm not 100% sure on how the system works.

The tach things is really odd.
You should only need the wire to be fully connected from the igniter to the gauge. EA3 Pin 5, IE1 Pin 13 then plug A pin 3 for the 93 USDM. It's probably in a different plug and pin for the 91 USDM but I haven't checked.
Then making sure the gauge has power, ground and the capacitors are happy. I've not heard of other gauge circuit component failures.
 
1 - 19 of 19 Posts
Top