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

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).


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

PinWire colourCircuitDiagnostics
C-01BlueAlternator communication LIN lineComplex waveform
C-04GreyMAP & coolant temp sensors ground< 0.3V, ignition on
C-05BeigeIntake air temp sensor ground< 0.3V, ignition on
C-06RedFront O2 sensor ground< 0.3V, ignition on
C-07GreenFront O2 sensor signalComplex waveform
C-08YellowRear O2 sensor ground< 0.3V, ignition on
C-10RedCyl 3 injector10-14V, ignition on;
complex waveform when running
C-11WhiteCyl 2 injector10-14V, ignition on;
complex waveform when running
C-12GreenCyl 4 injector10-14V, ignition on;
complex waveform when running
C-13RedThrottle position sensor drive4.5-5.5V, ignition on
C-14Light blueMAP sensor drive4.5-5.5V, ignition on
C-15BlackThrottle position sensor ground< 0.3V, ignition on
C-16WhiteThrottle position sensor (sub) signal4.0-4.2V, ignition on & throttle pedal released
0.5-0.7V, ignition on & throttle pedal fully depressed
C-17BlackThrottle position sensor (sub) shield ground< 0.3V, ignition on
C-19BrownRear O2 sensor signalComplex waveform
C-20BlueCoolant temp signalIgnition 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-22GreyIntake air temp signalIgnition 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-25WhiteKnock sensor 1 signalEngine at idle will give 1-2V
Complex waveform signal
C-26GreenThrottle position sensor (main) signal0.8-1.0V, ignition ON & throttle pedal released
4.3-4.5V, ignition ON & throttle pedal fully depressed
C-27BrownMAP sensor signalIgnition on 4.0-4.2V
Engine at idle when warm, 100 kPa air pressure: 1.5-1.8V
Complex waveform signal
C-30PurpleCam position sensorIgnition on either 0V or 4-5V
Complex waveform signal
C-31BeigeCyl 1 injector10-14V, ignition on;
complex waveform when running
C-33GreenCyl 2 coilIgnition on: 0V
Complex waveform signal
C-34PinkCyl 3 coilIgnition on: 0V
Complex waveform signal
C-35Light blueCyl 4 coilIgnition on: 0V
Complex waveform signal
C-37BlueKnock sensor 2 signalEngine at idle will give 1-2V
Complex waveform signal
C-39PinkCrank position sensorIgnition on either 0V or 4-5V
Complex waveform signal
C-41GreyEvap canister purge valve10-14V, ignition on;
complex waveform when running
C-42YellowVVT control oil solenoid 10-14V, ignition on;
complex waveform when running
C-44Light greenCyl 1 coilIgnition on: 0V
Complex waveform signal
C-49PurpleFront O2 sensor heaterComplex waveform
C-50BlackECU ground #1< 0.3V, ignition on
C-51Light greenThrottle actuator close drive circuitComplex waveform signal
C-52RedRear O2 sensor heaterComplex waveform
C-53BlackECU ground #2< 0.3V, ignition on
C-54BrownThrottle actuator open drive circuitComplex waveform signal
C-55Light greenFront O2 sensor shield ground< 0.3V, ignition on
C-56BeigeRear O2 sensor shield ground< 0.3V, ignition on

E connector pinout, wiring and diagnostics

PinWire colourCircuitDiagnostics
E-01BeigeIgniton on signalIgnition OFF or ACC: 0-0.3V
Ignition ON: 10-14V
E-02PurpleRadiator fan relay #10-0.3V: A/C switch off, ignition ON, coolant temp > 97ºC
10-14V: A/C switch off, ignition ON, coolant temp < 95ºC
E-03YellowAccelerator pedal (sub) signal0.325-0.425V, ignition ON & throttle pedal released
2.15-2.25V, ignition ON & throttle pedal fully depressed
E-04Light blueElectric load sensor power4.5-5.5V ignition ON
E-05WhiteAccelerator pedal (sub) ground< 0.3V, ignition on
E-06BlackAccelerator pedal (sub) power4.5-5.5V ignition ON
E-08Light greenCruise control commands0-0.2V 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-09BlueA/C refrigerant pressure sensor ground< 0.3V, ignition on
E-14GreyA/C refrigerant pressure sensor power4.5-5.5V ignition ON
E-16BeigeAccelerator pedal (main) signal0.7-0.8V, ignition ON & throttle pedal released
4.35-4.45V, ignition ON & throttle pedal fully depressed
E-17Green(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-18Light blueBrake light switch signal0V: ignition ON, brake pedal released
10-14V: ignition ON, brake pedal pressed
E-19BlueAccelerator pedal (main) ground< 0.3V, ignition on
E-20BrownAccelerator pedal (main) power4.5-5.5V ignition ON
E-21PinkBlower motor (manual A/C models) signalIgnition 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-22BrownGrounds for:
* Electric load sensor
* Battery temperature sensor
* Cruise control switch
< 0.3V, ignition on
E-24RedFuel pump relayComplex waveform
E-27GreenRadiator fan relay #2 and 30-0.3V: A/C switch off, ignition ON, coolant temp > 102ºC
10-14V: A/C switch off, ignition ON, coolant temp < 100ºC
E-28RedCAN high communication lineComplex waveform
E-29WhiteCAN low communication lineComplex waveform
E-33RedA/C refrigerant pressure sensor signal0.9-1.3V Engine running, A/C compressor off
1.6-2.6V Engine running, A/C compressor on
E-41GreyA/C compressor clutch relay0-0.3V Engine running, A/C compressor on
10-14V Engine running, A/C compressor off
E-42Purple(M/T) Clutch pedal switch #20-0.3V: ignition ON, clutch pedal depressed
10-14V: ignition ON, clutch pedal released
E-43Light greenStarter motor control relayIgnition ON: 0-0.3V
Ignition START: 6-12V
E-44BlueBrake switch signal (cruise control models only)0-0.3V: ignition ON, brake pedal pressed
10-14V: ignition ON, brake pedal released
E-48BlueElectric load sensor signal3.1V: Ignition ON, headlights ON high beam, blower speed MAX
3.4V: Ignition ON, minimal other loads
E-49PinkMain relay driver0-0.3V: Ignition ON
10-14V: 10 seconds after ignition: OFF
E-55BluePermanent powerFed from FI (fuse 28) 15A via main relay
E-56BluePermanent powerFed 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.

PinWire colourCircuit
4BlueHill descent control switch
5Light blueBrake light signal
9WhiteCAN low communication line
11YellowIgnition power supply
12BlackABS/ESP module ground
13GreenPump motor power supply
15PinkWheel speed sensor signal (rear right)
16Light blueWheel speed sensor power (rear right)
17Light greenWheel speed sensor signal (front left)
18RedWheel speed sensor power (front left)
19BrownBrake booster pressure signal
20GreyBrake booster pressure sensor power
21BlueBrake booster pressure sensor ground
22RedCAN high communication line
25BlackABS/ESP module ground
26Light blueSolenoid valves power
27GreenBrake light signal
28BeigeService mode connector
29YellowWheel speed sensor signal (rear left)
30BrownWheel speed sensor power (rear left)
31GreenWheel speed sensor signal (front right)
32PurpleWheel speed sensor power (front right)
34WhiteESP off switch
36Brown(M/T) reverse light switch

Accelerator pedal

PinWire colourCircuit
1YellowSignal, accelerator pedal sub circuit
2WhiteGround, accelerator pedal sub circuit
3BlackPositive 5V feed, accelerator pedal sub circuit
4BeigeSignal, accelerator pedal main circuit
5BlueGround, accelerator pedal main circuit
6BrownPositive 5V feed, accelerator pedal main circuit

Accelerator pedal sensor parameters

From Suzuki diagnostic data, including the range of voltages that are counted as acceptable for each signal. Both signals need to be in agreement about the accelerator pedal position within these tolerances for the ECU to accept the pedal position.
APP 1 / Main signalAPP 2 / sub signalAccelerator position
0.7 – 0.8 V0.325 – 0.425 V0 – 2% travel
4.35 – 4.45 V2.15 – 2.25 V90 – 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 numberWire colourItem
1Light blue (L); light green (R)Headlight levelling motor
2Blue (L); brown (R)High beam
3Green (L); yellow (R)Headlight on signal
4BlackGround (headlight)
5Red (L); purple (R)Park light
6BlackGround (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