Hi All. I am hooking up an EMU Classic to an SC300 that has been NA-T and is currently running a MKIV ECU (running well). I am adding the EMU so I can tune it to my liking. I am new to the tuning world, but am starting by building a harness to connect the SC/JZA80 harness connector to the EMU. I have been doing my homework to figure out which connector pin maps to which EMU pin. Here is a link to a comprehensive spreadsheet that shows the mapping I think is correct. ( EMU_To_JZA80MT_PinOut - Google Sheets ) I am looking for any feedback from folks with more experience than me to help me get the spreadsheet filled in. In the diagram I refer to the 80 pin connector as 80P and the 40 pin connector as 40P. I then refer to the EMU connectors as EMUB and EMUG for black grey respectively. The questionable cells are highlighted in orange.
The main questions I have are:
What do you connect Ignition Switch (40P-01) to on the EMU?
What pins do you connect Idle Speed Control pins to on the EMU? Which one to which pin?
How do you connect the charcoal canister to the EMU?
How do you connect the Check Engine Light to the EMU?
Which TPS sensor on the JZA80 connector is used where on the EMU? (80P-43, 40P-40)
Which Speed Sensor on the JZA80 connector is used where on the EMU? (80P-23, 40P-02)
Does the Battery Power on the JZA80 (40P-33) get connected to any pin on the EMU?
Does the Switched Power on the JZA80 (40P-32) get connected o any pin on the EMU?
How do you connect the A/C Clutch Relay (40P-23) and A/C Signal (40P-34) pins to the EMU?
Do you connect the JZA80 Main Relay (40P-24) to the EMU?
If these questions have been addressed elsewhere and I couldn’t find them, it was not due to a lack of trying.
Gonna leave this here, this is from WHP (ecumaster USA). They make a JZA80 NA PNP ECU that you can cross reference with.
On a Classic, no you don’t need to use constant power for anything.
I’d have to double check the diagrams, but very often with N/A Toyota’s (they are different chassis wiring then the turbo cars) you’ll just connect the ignition switch 12V straight to the main relay (circuit opening in Toyota speak) relay control. The OEM ECU would handle this, the EMU doesn’t need to, nor does it have the IO for it
There’s a good diagram for controlling a unipolar stepper motor in the EMU training manual, also in the help files in the software. With Ecumaster you don’t need the 12V in the center pins, you can just wire H bridge 1A to pin 1, 1B to 3, 2A to 4, 2B to 6.
Don’t waste your time trying to control emissions stuff on an EMU classic. Get it running first, and then you can struggle with that lol, Classic is a basic ecu and emissions compliance is not top of mind.
Check engine light has an output parameters, any AUX out can be used to control it. (inj and h bridge can too but you’re going to use all of them to control the engine)
TPS is probably going to be pin 43, On a 4 pin Toyota TPS sensor one pin is a idle switch and the other 3 are signal, 5V and sensor ground for the actual position sensor. You do not need the idle switch.
On JZA80 I think VSS comes from the cluster… don’t quote me on that. You can try both but off the top of my head I’d be leaning to the 40P connector option.
battery power no, switched power yes. I’d connect both pins to the EMU’s Grey pin 17 as the Classic only having 1 power pin struggles to stay on with a drop in voltage, for example during starting. The ignition switch you have connected to pin 1 is not sufficient to power the ecu. The others are feeds from the main relay
There is a good diagram for A/C in the help manual, AC relay is an AUX output, request is going to an analog (4k7 pull up enable).
Other notes after reading your sheet’:
18 awg is unnecessary for signal wires, overkill even for injectors. I use 22 for signals, 5V etc and 20 awg for outputs (unless the ECU is directly driving an ignition coil, like a 2 pin dumb coil)
Connect all the EMU’s power grounds to grounds. Even if that means splicing them all together. ECU’s do most of their work switching low side (ground path) and more AWG there the better.
Tach does come from igniter on these older toyota’s
EMU doesn’t monitor the feedback from ignition coils like the OEM toyota ecu does. It uses knock to detect misfires/incorrect ignition events
EMU uses a low rpm and the voltage drop to infer the engine is in cranking state and refers to the correct tables for cranking and enrichment fuel etc, you’ve answered this but I’m confirming.
You can use an analog input to address a high load idle state, but the PID’s present in the idle control parameters can also (retroactively) compensate for changes in idle rpm due to alternator load etc. In my experience with good setup this can actually react faster then an OEM ecu of this era does.
Some of these are answerable questions by looking in the right places, some are not spelled out very clearly and require experience to grasp. I recommend reading the EMU training manual and the JZA80 FSM electrical sections. You sheet is more organized and clear then 90% of people on here; you’re on the right path. I usually do not want to invest the time it takes to write out a post like this, but imo you’ve earned these answers.
I am building my own PNP connector from an old ECU I tore apart. I plan to use the heavier gauge wires for the 10” span between the EMU connector and the JZA80 ECU connector. I already had a bunch of 18 laying around.
I de-soldered the connector, cut off the front end of the ECU box and did some grinding and riveting.
I will now wire the EMU classic connectors to this and then pot it with resin.
I can then swap the EMU classic ECU with my existing JZA80 ECU while I get the tune dialed in. Save me about $400.
Any thoughts on my plan forward? Once I finish building my PNP harness I will upload my current base map and see if it starts. From there, I am sure I will need to do lots more reading to get the tune dialed in.
You asked if you need to connect anything to battery power. In this instance, no.
You will need to connect switched power to the EMU, and as I outlined use the main relay output not the ignition switch signal.
The EMU can do tach but if your fake igniter handles it and is accurate then no need I suppose.
I’ve built more then a few PNP’s, I’d wait to pot it until you’ve at least got the engine running. All too often I have to change something or find a better way.
I’d also really counter the narrative “saved me $400” lol. You traded that for you time getting this far, arguably better learning experience but still cost something. All depends which one can afford I guess…
