Toyota Celica GT4 ST165 ECU pin out and wiring diagram

Simply lift back the carpet adjacent to the centre console in the passenger foot well - picture

When you modify your car then you are going to have to alter some of the signals being sent to, or, from the ECU, in order to increase the output power beyond the original design limitations, or alter the operation of a specific system. This may also be useful during fault finding.

Note that the ECU is installed "upside down". Therefore to make a direct comparison between the ECU and the diagram, the picture has been turned upside down - easier than trying to twist the ECU!

Abbreviation	Wire colour	Means...	What does it do?	Anything else?
E02	White/Black	Earth	Attached to engine block
ISC-2	Green/Black	Idle Stabilisation Control	Opens a valve below the throttle body to control the idle speed rpm	Raises idle speed when aircon running, and when engine cold
IGT	White	Igniter signal	Controls spark to spark plugs, in effect fires the coil
E1	Brown	Earth	Attached to engine block
TVIS	Light Green	Operates TVIS VSV	Opens a set of butterflies in the intake manifold at 4300rpm
#3	Yellow	Injector signal	Fires No 3 fuel injector
#4	Blue	Injector signal	Fires No 4 fuel injector
VF	Violet/Yellow	Diagnostic connector	Check connector?	Any connections off?
T	Orange	Diagnostic connector	Check connector?	Any connections off?
VTA	White	Throttle position sensor	Informs ECU of throttle position	Very fine setup of the TPS sensor is required
IDL	Pink	Idle signal	Tells the ECU the car is at idle	Signal is from throttle position sensor
HT	Red/Green	To lambda sensor	12V lambda sensor heater	Heats the lambda sensor to speed up a more accurate reading when the sensor is not up to operating temperature
OX	White	Lambda sensor voltage	A voltage feedback from the exhaust to "tune" the engine whilst at a steady rpm	Also feeds the OX pin at the diagnostic connector
E2	Brown	Earth
E22	Brown	Earth for AFM	?
EGR	Blue/Red	EGR VSV	Operates the EGR
A/C	Black/White	Clutch relay signal	Engages the AC compressor magnetic clutch
W	Green	Check engine light	Puts on the yellow engine check light	Indicates via a series of codes any stored faults
FPU	Black/Red	FPR control	Sends a signal to the fuel pressure VSV to increase the fuel pressure	Only the 165 has this arrangement...
KNK	Clear	Knock sensor	Sensor feeds in a voltage to the ECU proportional to the amount of knock in the engine...	If knock is sensed then the ignition timing is retarded
PIM	Red/White	TPS voltage	Feeds a voltage to the ECU proportional to the boost pressure	This signal is altered with an FCD if you want to run high boost. Also controls the dash boost gauge. A lot of websites/articles/books call this the P/M - they didn't read the connections carefully, it should be the PIM signal. In fact Toyota have made this mistake in some of their workshop manuals
THG	Blue	EGR temp sensor	Not fitted in UK	Only fitted to USA cars
+B	Black/Yellow	12V supply to ECU	12V fed after ignition key is turned
+B1	Black/Yellow	12V supply to ECU	12V fed after ignition key is turned	Good place to attach items that you don't want to stay on after engine turned off e.g. BG light

Abbreviation	Wire colour	Means...	What does it do?	Anything else?
E01	White/Black	Earth	Attached to engine block
ISC-1	Green/White	Idle Stabilisation Control	Opens a valve below the throttle body to control the idle speed rpm
STA	Black	Starting signal	12V fed to the ECU whilst the car is trying to start
STJ	Green	Cold start injector	Signal to control the 5th injector when starting the car
#1	Red/Black	Injector signal	Fires No 1 fuel injector
#2	Light Green	Injector signal	Fires No 2 fuel injector
G-	Red	Distributor signals	Ground for G1, G2 and NE
G1	Dark Green	Distributor signals	Sends crankshaft angle information	Allows ECU to determine the position of each piston, adjust injector and ignition timing
G2	White	Distributor signals	Sends crankshaft angle information	As above, but 180^o out from G1
NE	Black	Engine rpm signal	Sends the engine speed and crankshaft angle to the ECU	Positive signal from 24 tooth sensor
FPR	Blue/Red	Fuel Pump Relay	Clicks on the fuel relay when you turn the ignition key	If it doesn't activate the fuel relay the car won't start
IGF	White/Red	Spark confirmation signal	Used to detect a fault within the igniter
THW	Red	Water temperature sensor	Informs ECU of water temperature	Probably used to correct fuel and ignition maps
WIN	Light Green/Black	Intercooler computer signal	Error reporting?
TPC	Black/White	TVSV signal	Allows extra boost in 3+ gears ~2psi	Don't cut this wire, pull the pipe off from the wastegate actuator instead!
SPD	Blue/White	Speed sensor	Monitors car speed
STP	Green/White	Stop light switch	Monitors the brake light switch	To inform the ECU when braking, to apply deceleration fuel cut
THA	Grey	AFM air intake temp	Tells the ECU the temp of the incoming air
VS	Grey/Black	AFM signal	Stopped - idle signal
VC	Pink/Blue	AFM signal	Variable - flap position signal
BATT	Pink	Battery supply	Supplies power to ECU via the 15A engine bay fuse	Permanent 12V feed to the battery even when the ignition is off
ELS	Orange	Electrical idle up	Increases idle speed due to large current drawn by headlights and demister

Want a print out the ECU diagram and pins for a handy reference? Click on the download button below. Note that the ECU pin outs have been altered to the correct way around as you are looking at the ECU.