JB74 wiring and wire connectors

This certainly can’t be exhaustive, as I’m not equipped to redraw or reverse-engineer the entire wiring loom. I’ll do what I can to document different things here as I find stuff and as I go.

This information wouldn’t be possible without the excellent research into connectors and wiring by Royce Murphy, an absolute legend of the Suzuki world and may he RIP. Royce provided a heap of info through Auzookers and also various FB pages over the years. I’m providing this info here free because one of the big bugbears was the way accessories companies would pump for info & then give zero credit; this way, everyone can have access to find the $2 connector they need instead of buying a $40 piggyback connector made poorly.

Sections

• Wiring
  • 4wd wiring (and vacuum circuit)
• Wiring connectors
  • ECU
  • ABS/ESP module
  • Accelerator pedal
  • Headlights (LED)

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Wiring

Leaving this blank till I work out a decent way to draw the circuits, but I’ll add info here where I need to.

4wd wiring (and vacuum circuit)

This is mostly as you get asked a lot of questions when people want to troubleshoot 4wd stuff and it’s easier to have it all on one diagram. The 4wd system is manual, also electric and additionally controlled by a vacuum circuit in the JB74.

The transfer case shifts fully mechanically to a) send power out of the front prop shaft in 4wd and b) engage the low range reduction when you shift to low range. Additionally, the transfer case engages a switch to say it is in 4wd and a further switch for when it is low range. These mode changes are communicated via the CAN bus e.g. to disable autonomous braking and traction control/ESP in low range, but also to use the ABS/ESP module to brake an individual wheel spinning on an axle more aggressively than it does in high range.

The hubs are engaged by a vacuum system. When it shifts into 4wd it uses stored vacuum from a reservoir in the front wheel arch to engage the locking hubs through one solenoid, assuming it sees sufficient vacuum. When shifting out of 4wd it uses a different vacuum solenoid to pull the engagement rings of the hubs off and disengage the front differential.

The 4wd module also receives data on the CAN bus from the transmission control module in automatic Jimnys. This includes montoring the gear data and the output speed of the transmission. This monitoring will throw an error if you try to use the low range switch to trick the car into thinking it is in low range when it is, in fact, in high range. The same monitoring does not occur in a manual Jimny as they lack sensors for the gearbox output speed and gear position.

Across the CAN bus, the 4wd module looks for engine running and vehicle speed status from the ECU. It also provides A/C turnoff and transfer state back to the ECU, info on the 4wd status for the gauge cluster, and the status of the transfer case to both the ESP module and the transmission module (for automatics).

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Wiring connectors

ECU

This is a big fat section so strap in. I’ve also compiled the diagnostics info from various bits and bobs to hopefully cover off on expected voltages. I will need to dig out the oscilloscope to capture some of the waveforms for complex sensors, as many do not produce a single voltage, but that can wait. To keep consistency with the factory labelling the two connectors are labelled C and E as per their wiring harnesses.

C connector pinout, wiring and diagnostics

Pin	Wire colour	Circuit	Diagnostics
C-01	Blue	Alternator communication LIN line	Complex waveform
C-04	Grey	MAP & coolant temp sensors ground	< 0.3V, ignition on
C-05	Beige	Intake air temp sensor ground	< 0.3V, ignition on
C-06	Red	Front O2 sensor ground	< 0.3V, ignition on
C-07	Green	Front O2 sensor signal	Complex waveform
C-08	Yellow	Rear O2 sensor ground	< 0.3V, ignition on
C-10	Red	Cyl 3 injector	10-14V, ignition on; complex waveform when running
C-11	White	Cyl 2 injector	10-14V, ignition on; complex waveform when running
C-12	Green	Cyl 4 injector	10-14V, ignition on; complex waveform when running
C-13	Red	Throttle position sensor drive	4.5-5.5V, ignition on
C-14	Light blue	MAP sensor drive	4.5-5.5V, ignition on
C-15	Black	Throttle position sensor ground	< 0.3V, ignition on
C-16	White	Throttle position sensor (sub) signal	4.0-4.2V, ignition on & throttle pedal released 0.5-0.7V, ignition on & throttle pedal fully depressed
C-17	Black	Throttle position sensor (sub) shield ground	< 0.3V, ignition on
C-19	Brown	Rear O2 sensor signal	Complex waveform
C-20	Blue	Coolant temp signal	Ignition on will give voltages at coolant temps as follows: * 0.2-0.5V @ 100ºC * 1.0-1.4V @ 50ºC * 3.2-3.6V @ 0ºC
C-22	Grey	Intake air temp signal	Ignition on will give voltages at air temps as follows: * 0.4-0.8V @ 80ºC * 1.3-1.7V @ 40ºC * 3.2-3.6V @ 0ºC
C-25	White	Knock sensor 1 signal	Engine at idle will give 1-2V Complex waveform signal
C-26	Green	Throttle position sensor (main) signal	0.8-1.0V, ignition ON & throttle pedal released 4.3-4.5V, ignition ON & throttle pedal fully depressed
C-27	Brown	MAP sensor signal	Ignition on 4.0-4.2V Engine at idle when warm, 100 kPa air pressure: 1.5-1.8V Complex waveform signal
C-30	Purple	Cam position sensor	Ignition on either 0V or 4-5V Complex waveform signal
C-31	Beige	Cyl 1 injector	10-14V, ignition on; complex waveform when running
C-33	Green	Cyl 2 coil	Ignition on: 0V Complex waveform signal
C-34	Pink	Cyl 3 coil	Ignition on: 0V Complex waveform signal
C-35	Light blue	Cyl 4 coil	Ignition on: 0V Complex waveform signal
C-37	Blue	Knock sensor 2 signal	Engine at idle will give 1-2V Complex waveform signal
C-39	Pink	Crank position sensor	Ignition on either 0V or 4-5V Complex waveform signal
C-41	Grey	Evap canister purge valve	10-14V, ignition on; complex waveform when running
C-42	Yellow	VVT control oil solenoid	10-14V, ignition on; complex waveform when running
C-44	Light green	Cyl 1 coil	Ignition on: 0V Complex waveform signal
C-49	Purple	Front O2 sensor heater	Complex waveform
C-50	Black	ECU ground #1	< 0.3V, ignition on
C-51	Light green	Throttle actuator close drive circuit	Complex waveform signal
C-52	Red	Rear O2 sensor heater	Complex waveform
C-53	Black	ECU ground #2	< 0.3V, ignition on
C-54	Brown	Throttle actuator open drive circuit	Complex waveform signal
C-55	Light green	Front O2 sensor shield ground	< 0.3V, ignition on
C-56	Beige	Rear O2 sensor shield ground	< 0.3V, ignition on

E connector pinout, wiring and diagnostics

Pin	Wire colour	Circuit	Diagnostics
E-01	Beige	Igniton on signal	Ignition OFF or ACC: 0-0.3V Ignition ON: 10-14V
E-02	Purple	Radiator fan relay #1	0-0.3V: A/C switch off, ignition ON, coolant temp > 97ºC 10-14V: A/C switch off, ignition ON, coolant temp < 95ºC
E-03	Yellow	Accelerator pedal (sub) signal	0.325-0.425V, ignition ON & throttle pedal released 2.15-2.25V, ignition ON & throttle pedal fully depressed
E-04	Light blue	Electric load sensor power	4.5-5.5V ignition ON
E-05	White	Accelerator pedal (sub) ground	< 0.3V, ignition on
E-06	Black	Accelerator pedal (sub) power	4.5-5.5V ignition ON
E-08	Light green	Cruise control commands	0-0.2V Cruise switch ON 0.3-0.6V Cancel switch ON 0.88V Limit switch ON 1.2-1.6V SET – switch ON 2.0-2.4V RES + switch ON 3.5-4.3V Ignition ON no other switches pressed
E-09	Blue	A/C refrigerant pressure sensor ground	< 0.3V, ignition on
E-14	Grey	A/C refrigerant pressure sensor power	4.5-5.5V ignition ON
E-16	Beige	Accelerator pedal (main) signal	0.7-0.8V, ignition ON & throttle pedal released 4.35-4.45V, ignition ON & throttle pedal fully depressed
E-17	Green	(A/T) Transmission range sensor (M/T) Clutch pedal switch #1	0V: (A/T) ignition ON, transmission P or N (M/T) ignition ON, clutch pedal depressed 10-14V: (A/T) ignition ON, transmission not in P or N (M/T) ignition ON, clutch pedal released
E-18	Light blue	Brake light switch signal	0V: ignition ON, brake pedal released 10-14V: ignition ON, brake pedal pressed
E-19	Blue	Accelerator pedal (main) ground	< 0.3V, ignition on
E-20	Brown	Accelerator pedal (main) power	4.5-5.5V ignition ON
E-21	Pink	Blower motor (manual A/C models) signal	Ignition ON gives the following: 10-14V: blower switch off 5-7V: blower switch 1st position 0-0.3V: blower switch 2nd or higher position
E-22	Brown	Grounds for: * Electric load sensor * Battery temperature sensor * Cruise control switch	< 0.3V, ignition on
E-24	Red	Fuel pump relay	Complex waveform
E-27	Green	Radiator fan relay #2 and 3	0-0.3V: A/C switch off, ignition ON, coolant temp > 102ºC 10-14V: A/C switch off, ignition ON, coolant temp < 100ºC
E-28	Red	CAN high communication line	Complex waveform
E-29	White	CAN low communication line	Complex waveform
E-33	Red	A/C refrigerant pressure sensor signal	0.9-1.3V Engine running, A/C compressor off 1.6-2.6V Engine running, A/C compressor on
E-41	Grey	A/C compressor clutch relay	0-0.3V Engine running, A/C compressor on 10-14V Engine running, A/C compressor off
E-42	Purple	(M/T) Clutch pedal switch #2	0-0.3V: ignition ON, clutch pedal depressed 10-14V: ignition ON, clutch pedal released
E-43	Light green	Starter motor control relay	Ignition ON: 0-0.3V Ignition START: 6-12V
E-44	Blue	Brake switch signal (cruise control models only)	0-0.3V: ignition ON, brake pedal pressed 10-14V: ignition ON, brake pedal released
E-48	Blue	Electric load sensor signal	3.1V: Ignition ON, headlights ON high beam, blower speed MAX 3.4V: Ignition ON, minimal other loads
E-49	Pink	Main relay driver	0-0.3V: Ignition ON 10-14V: 10 seconds after ignition: OFF
E-55	Blue	Permanent power	Fed from FI (fuse 28) 15A via main relay
E-56	Blue	Permanent power	Fed from FI (fuse 28) 15A via main relay

ABS-ESP module

Another biggish one, but not quite as big as the ECU. One circuit (the brake master cylinder pressure) appears to be 5V.

Pin	Wire colour	Circuit
4	Blue	Hill descent control switch
5	Light blue	Brake light signal
9	White	CAN low communication line
11	Yellow	Ignition power supply
12	Black	ABS/ESP module ground
13	Green	Pump motor power supply
15	Pink	Wheel speed sensor signal (rear right)
16	Light blue	Wheel speed sensor power (rear right)
17	Light green	Wheel speed sensor signal (front left)
18	Red	Wheel speed sensor power (front left)
19	Brown	Brake booster pressure signal
20	Grey	Brake booster pressure sensor power
21	Blue	Brake booster pressure sensor ground
22	Red	CAN high communication line
25	Black	ABS/ESP module ground
26	Light blue	Solenoid valves power
27	Green	Brake light signal
28	Beige	Service mode connector
29	Yellow	Wheel speed sensor signal (rear left)
30	Brown	Wheel speed sensor power (rear left)
31	Green	Wheel speed sensor signal (front right)
32	Purple	Wheel speed sensor power (front right)
34	White	ESP off switch
36	Brown	(M/T) reverse light switch

Accelerator pedal

Pin	Wire colour	Circuit
1	Yellow	Signal, accelerator pedal sub circuit
2	White	Ground, accelerator pedal sub circuit
3	Black	Positive 5V feed, accelerator pedal sub circuit
4	Beige	Signal, accelerator pedal main circuit
5	Blue	Ground, accelerator pedal main circuit
6	Brown	Positive 5V feed, accelerator pedal main circuit

Accelerator pedal sensor parameters

APP 1 / Main signal	APP 2 / sub signal	Accelerator position
0.7 – 0.8 V	0.325 – 0.425 V	0 – 2% travel
4.35 – 4.45 V	2.15 – 2.25 V	90 – 100% travel

Headlights (LED)

These use a 6 pin Sumitomo TS series connector. If making up a piggyback harness you need both the male and female connectors: 6188-0175 and 6189-0323. If just remaking the headlight connector on the car side of the wiring loom then 6189-0323 suffices.

Pin number	Wire colour	Item
1	Light blue (L); light green (R)	Headlight levelling motor
2	Blue (L); brown (R)	High beam
3	Green (L); yellow (R)	Headlight on signal
4	Black	Ground (headlight)
5	Red (L); purple (R)	Park light
6	Black	Ground (high beam)

Indicators

2 pin 90980-11019

DRL/fog lights

3 pin 6187-3231 and 6180-3241

Dashboard switches

6098-3810 6098-3802

Replacement dashboard switches (short Toyota)

JAE Electronics IL-AG5-5S-S3C1 (also matches reverse camera input to Bosch 7″ head unit) and IL-AG5-5P-S3C1

Headunit reverse/park/handbrake

Yazaki 7283-5830 and 7282-5830