XJ750J WIRING DIAGRAM

 

 

 

 

Starting circuit operation

 

The starting circuit on this model consists of the starter motor, starter relay, and the starting-circuit cut-off relay. If the engine stop switch and the main switch are both on, the starter motor can operate only if:

 

a.    The transmission is in neutral (the neutral switch is on).

 

or if

 

b.    The clutch lever is pulled to the handlebar (the clutch switch is on) and the sidestand is up (the sidestand switch is on.)

 

Starting-circuit cut-off relay inspection

 

1.    Open the seat, and remove the fuel tank.

 

2.    Remove the starting-circuit cut-off relay from the frame, and disconnect the connector.

 

The starting-circuit cut-off relay prevents the starter from operating when neither of these conditions has been met. In this instance, the starting-circuit cut-off relay is off so current cannot reach the starter motor.

 

When one or both of the above conditions have been met, however, the starting-circuit cut-off relay is on, and the engine can be started by pressing the starter switch.

 

 

 

1. Starting-circuit cut-off relay

 

3. Check the resistance of the relay coil windings with the pocket tester. If the resistance is not within specification, replace the relay.

 

 

4. Check the relay function with a 12 volt battery and the pocket tester. Connect the leads as shown in the illustration. If the resistance readings do not equal those shown in the illustration, replace the relay.

 

 

5. Check the diode in the starting circuit cut-off relay with the pocket tester as shown in the illustration. Replace the relay if the diode is damaged.

 

 

NOTE:

Only the Yamaha Pocket Tester will give a 9.5Ω reading when testing continuity. The particular characteristics of other testesr will very the continuity test readings.

 

 

D. CHARGING SYSTEM

 

B. A.C. Generator

1. Checking method.

a.  Connect D.C. voltmeter to the battery terminals.

b.  Start engine.

c.   Accelerate engine to approximately 2,000 r/min or more and check generated voltage.

Generated voltage: 14.5± 0.3V

d. If the indicated voltage cannot be reached, then perform the tests in step 2.

CAUTION:

Never disconnect wires from the battery while the generator is in operation. If the battery is disconnected, the voltage across the generator terminals will increase, damaging the semiconductors.

2. Resistance test of field coil and stator coil.

Check the resistance between terminals. If resistance is out of specification, coil is broken. Check the coil connections. If the coil connections are good, then the coil is broken inside and it should be replaced.

Field coil resistance:	(Green-Brown)
4.0Ω ± 10% at 20°C (68°F)
Stator coil resistance	(White-White)
0.46Ω ± 10% at 20°C (68°F)

C. Voltage Regulator

The IC Voltage Regulator is a small and, normally, very reliable component. Due to its construction, it is lightweight and free from the wear and misadjustment associated with mechanical voltage regulators. If the following inspection reveals that the regulator is faulty, it cannot be adjusted and must be replaced.

1. Checking IC Voltage Regulator

a.   Remove the seat.

b.   Remove the left side cover.

c.  Measure the specific gravity of the battery fluid. If it is less than 1.260, remove the battery and recharge until it is more than 1.260. (See page 124 for charging procedures)

d.  Check the battery terminals and couplers for looseness.

e.  Connect two Yamaha pocket testers to the regulator coupler as illustrated.

CAUTION:

Be careful not to let the tester leads short circuit when connecting them to the regulator snap connector leads.

f.   Turn the main switch on. Make sure that V₂ is less than 1.8V.

NOTE:

Do not turn on lights or signals.

g.   Make sure that V2 gradually increases up to 9 ~ 11V when the engine is started and its revolutions go up.

h. Make sure that Vi maintains the level of 14.2 ~ 14.8V even when engine revolutions increase.

i. If these levels are not maintained, the regulator is defective and must be replaced.

2. Checking the silicon rectifier a. Check the silicon rectifier as specified using the Yamaha pocket tester.

Checking element	Pocket tester connecting point		Good	Replace (element shorted)	Replace (element opened)
	(+) (red)	(-) (black)
D1	d	a	0	0	X
	a	d	X	0	X
D2	d	b	O	0	X
	b	d	X	0	X
D3	d	c	0	0	X
	c	d	X	0	X
D4	a	e	0	0	X
	e	a	X	0	X
D5	b	e	0	0	X
	e	b	X	o	X
D6	c	e	o	0	X
	e	c	X	0	X

0 : Continuity

x : Discontinuity (∞)

b. Even if only one of the elements is broken, replace the entire assembly.

CAUTION:

The silicon rectifier can be damaged if subjected to overcharging. Special care should be taken to avoid a short circuit and/or incorrect connection of the positive and negative leads at the battery. Never connect the rectifier directly to the battery to make a continuity check.

E. IGNITION SYSTEM

Above circuit diagram shows only ignition circuit in wiring diagram.

Description

This model is equipped with a battery operated, fully transistorized, breakerless ignition system. By using magnetic pickup coils, the need for contact breaker points is eliminated. This adds to the dependability of the system by eliminating frequent cleaning and adjustment of points and ignition timing. The TCI (Transistor Control Ignition) unit incorporates an automatic advance circuit controlled by signals generated by the pickup coil. This adds to the dependability of the system by eliminating the mechanical advancer. This TCI system consists of two units; a pickup unit and an ignitor unit.

NOTE:

The ignition circuit can be operated only when the sidestand is up (the sidestand switch is on) or the transmission is in neutral.

Operation

The TCI functions to the same principle as a conventional DC ignition system with the exception of using magnetic pickup coils and a transistor control box (TCI) in place of contact breaker points.

1. Pick-up unit

1. Pick-up coils

The pickup unit consists of two pickup coils and a flywheel mounted onto the crankshaft. When the projection on the flywheel passes a pickup coil, a signal is generated and transmitted to the ignitor unit. The width of the projection on the flywheel determines the ignition advance.

 

2- Ignitor unit

This unit controls when form, duty control, switching, electronic ignition advance, etc. They duty control circuit reduces electrical consumption by controlling the duration of the primary ignition current.

The ignitor unit also has a protective circuit for the ignition coil. If the ignition switch is on and the crankshaft is not turning, the protective circuit interrupts the current flow to the primary coil after a few seconds. When the crankshaft is turning, however, the ignitor unit sends current to the primary coil.

 

CAUTION:

Do not run the engine without any spark plug cap(s) in place. Due to the high secondary voltage, it is possible to damage the internal insulation of the secondary coil.

 

3. Sidestand relay

The sidestand relay operates by shorting the TCI control current. When the side-stand is down, the sidestand relay is closed, and the TCI control current is grounded through the sidestand relay. Thus, the engine will not run with the sidestand down unless the transmission is in neutral.

 

D. Troubleshooting/Inspection

1. The entire ignition system can be checked for misfire and weak spark using the Electro Tester. If the ignition system will fire across a sufficient gap, the entire ignition system can be considered good. If not, proceed with individual component tests until the problem is found.

a. Warm up engine thoroughly so that all electrical components are at operating temperature.

b. Stop the engine and connect the tester as shown.

c. Start the engine and increase the spark gap until misfire occurs. (Test at various r/min between idle and red line.)

Minimum spark gap: 6 mm (0.24 in)

CAUTION:

Do not run engine in neutral above 6,000 r/min for more than 1 or 2 seconds.

2. If the ignition system should become inoperative, the following troubleshooting aids will be useful.

 

3. Ignition coil

a. Coil spark gap test.

1)   Remove the fuel tank and disconnect the ignition coil from wire harness and spark plugs.

2)   Connect the Electro Tester as shown.

3)  Connect fully charged battery to tester.

4)  Turn on spark gap switch and the increase gap to maximum unless misfire occurs first.

Minimum spark gap: 6 mm (0.24 in)

b. Direct current resistance test. Use a pocket tester or equivalent ohmmeter to determine resistance and continuity of primary and secondary coil windings.

Standard value:

Primary coil resistance:
2.5Ω ± 10% at 20°C (68°F)

Secondary coil resistance:
11 KΩ ± 20% at 20% (68°F)

Primary coil check

 

Secondary coil check

 

4. Spark plug

The life of a spark plug and its discoloring vary according to the habits of the rider. At each periodic inspection, replace burned or fouled plugs with new ones of the specified type. It is actually economical to install new plugs often since it will tend to keep the engine in good condition and prevent excessive fuel consumption.

a.    Inspection

1)   Inspect and clean the spark plug every 4,000 km (2,500 mi) and replace after initial 13,000 km (8,000 mi).

2)   Clean the electrodes of carbon and adjust the electrode gap to the specification.

b.   Installation

Be sure to use the proper reach, type and electrode gap plug(s) as a replacement to avoid overheating, fouling or piston damage.

Type:BP7ES (NGK) or W22EP (ND)
Electrode gap:0.7 - 0.8 mm (0.028 - 0.031 in)
Tightening torque:2.0 m-kg (14.5 ft-lb)

 

Sidestand relay inspection

1.   Open the seat, and remove the fuel tank.

2.    Remove the sidestand relay from the frame, and disconnect the connector.

1. Sidestand relay

3. Check the resistance of the relay coil windings with the pocket tester. If the resistance is not within specification, replace the relay.

4. Check the relay contact breaker points with the pocket tester and a 12 bolt battery. Connect the leads as shown in the illustration. If the resistance readings do not equal those shown in the illustration, replace the relay.

1.   When the battery is connected.
2.   When the battery is disconnected.
3.    12 volt battery

 

LIGHTING SYSTEM

 

 

Above circuit diagram shows only lighting circuit in wiring diagram.

 

B. Lighting Tests and Checks

The battery provides power for operation of the headlight, taillight, and meter lights. If none of the above operates, always check battery voltage before proceeding further. Low battery voltage indicates either a faulty battery, low battery water, or a defective charging system. See "CHARGING SYSTEM" for checks of battery and charging system. Also check fuse condition. Replace any "open" fuses. There are individual fuses for various circuits (see complete Circuit Diagram).

NOTE:

Check the headlight bulb first before performing the following check.

1. Headlight check

NOTE:

When the main switch is turned to "ON", the headlight and meter lights come on automatically and the lights stay on until the ignition switch is turned to "OFF" even if the engine stalls.

HEADLIGHT DOES NOT COME ON WHEN ENGINE IS RUNNING
Check the headlight butb.	-----------> Faulty	Replace the bulb.
▼ Bulb OK ▼
Check the continuity of dimmer switch 1L/B-Y, L/B-G wires).	-----------> Open	Replace the switch.
▼ OK ▼
Check the continuity of starter switch (R/Y- L/B wire).	-----------> Open	Replace the switch
▼ OK ▼
Check the headlight fuse	-----------> Open	Replace the fuse.
▼ OK ▼
Check the continuity of main switch (R-Br wire).	-----------> Open	Replace the switch.
▼ OK ▼
Check the main fuse.	-----------> Open	Replace the fuse.
▼ OK ▼
Check battery voltage	-----------> Low	Charge or replace
▼ OK ▼
Faulty grounding or faulty connection of headlight switch

 

HIGH BEAM AND/OR LOW BEAM DO NOT LIGHT
Check for battery voltage at dimmer switch terminal	-----------> No voltage	Dimmer switch defective
▼ Voltage OK ▼
Check for battery voltage at headlight high beam or low beam terminal	-----------> No voltage	Open or poor connection between headlight and dimmer switch terminal
▼ Voltage OK ▼
Poor ground or poor connection of headlight wiring

2. Taillight does not work:

a. Check bulb

b. Check for 12V on blue wire.

c. Check for ground on black wire to tail/brake light and/or license light assembly.

 

G. SIGNAL SYSTEM

 

 

Above circuit diagram shows only signal circuit in wiring diagram.

B. Signal System Tests and Checks

The battery provides power for operation of the horn, brake light, indicator lights and flasher light. If none of the above operates, always check battery voltage before proceeding further. Low battery voltage indicates either a faulty battery, low battery water, or a defective charging system. See page 113 "CHARGING SYSTEM" for checks of battery and charging system. Also check fuse condition. Replace any "open" fuses. There are individual fuses for various circuits (see complete Circuit Diagram).

1.    Horn does not work:

a.   Check for 12V on brown wire to horn.

b.   Check for good grounding of horn (pink wire) when horn button is pressed.

2.    Brake light does not work:

a.   Check bulb.

b.   Check for 12V on yellow wire to brake light.

c.   Check for 12V on brown wire to each brake light switch (front brake and rear brake switches).

3.    Flasher light(s) do not work:

a.   Check bulb.

b.   Right circuit:

1)   Check for 12V on dark green wire to light.

2)  Check for ground on black wire to light assembly.

c.   Left circuit:

1)  Check for 12V on dark brown wire to light.

2)  Check for ground on black wire to light assembly.

d.   Right and left circuits do not work:

1)   Check for 12V on brown/white wire to flasher switch on left handlebar.

2)  Check for 12V on brown wire to flasher relay.

3)   Replace flasher relay.

4)   Replace flasher switch.

e.   Check flasher self-canceling system. (Refer to flasher self-canceling system.)

4. Neutral light does not work:

a.   Check bulb.

b.   Check for 12V on sky blue wire to neutral switch.

c.   Replace neutral switch.

6. Oil level warning light does not work:

a.   Connect oil level switch (black/red wire) to ground. If light comes on, check for proper oil level.

b.   If oil level is correct, replace oil level switch.

C. Self-Canceling Flasher System

1.    Description:

The self-canceling flasher system turns off the turn signal after a period of time or distance involved in turning or changing lanes. Generally, the signal will cancel after either 10 seconds, or 150 meters (490 feet), whichever is greater. At very low speed, the function is determined by distance; at high speed, especially when changing speeds the canceling determination is a combination of both times and distance.

2.    Operation:

The handlebar switch has three positions: L (left), OFF, and R (right). The switch lever will return to the "OFF" position after being pushed to L or R, but the signal will function. By pushing the lever in, the signal may be cancelled manually.

3.    Inspection

If the flasher self-canceling system should become inoperative, proceed as follows:

a. Pull of the 6-pin connector from the flasher canceling unit, and operate the handlebar switch, if the signal operates normally in L, R, and OFF, the following are in good condition.

1)   Flasher unit

2)   Bulb

3)   Lighting circuit

4)   Handlebar switch light circuit

If (1) through (4) are in good condition, the following may be faulty:

1)   Flasher canceling unit.

2)   Handlebar switch reset circuit.

3)   Speedometer sensor circuit.

b.   Pull off the 6-pin connector from the flasher canceling unit, and connect a tester (ohms x 100 range) across the white/green and the black lead wires on the wire harness side. Turn the speedometer shaft. If the tester needle swing back and forth between 0 and ∞, the speedometer sensor circuit is in good condition. If not, the sensor to wire harness may be inoperative.

c.    Pull the 6-pin connector from the flasher canceling unit. Check if there is continuity between the yellow/red lead wire on the wire harness side and the chassis.

Flasher switch OFF: ∞
Flasher switch L or R: 0 ohms

If the tester needle does not swing as indicated above, check the handlebar switch circuit and wire harness.

d.   If no defect is found with the above three check-ups and the flasher canceling system is still inoperative, replace the flasher canceling unit.

e.    If the signal flashes only when the handlebar switch lever is turned to L or R and it turns off immediately when the handlebar switch lever returns to center, replace the flasher canceling unit.

D. Switches

Switches may be checked for continuity with a pocket tester on the "ohm x 1" position. 1. Main switch

Switch Position	Wire Color
	R	Br	L/Y
ON	0----	--0--	----0
OFF
LOCK
P (parking)	0----	------	----0

2. "ENGINE STOP" Switch

Switch	Wire Color
Position	R/W	R/W
RUN	0----	----0
OFF

3. "START" switch

Button Position	Wire Color
	L/W	Ground
PUSH	O-----	----O
OFF

4. "LIGHTS" (Dimmer) switch

Switch Position	Wire Color
	Y	L/Y	G	G	L/G	Y/B
HI	0---	--O		0---	--O
LO		0---	--O		O----	--O

5. "TURN" switch

Switch Position	Wire Color
	Ch	Br/W	Dg	Y/n	Ground
L	0---	--O		0---	--O
L > N	0---	--O
N > Push
R > N		O---	--O
R		O---	--O	0---	--O

6. "HORN" Switch

Button Position	Wire Color
	P	Ground
PUSH	O---	------O
OFF

E. Battery

1. Checking

If the battery shows the following defects, it should be replaced.

a.   The battery voltage will not rise to a specific value or no gassing occurs in any cell even after many hours of charging.

b.   Sulfation of one or more cells is indicated by the plates turning white or an accumulation of material in the bottom of the cell.

c.   Specific gravity readings after a long slow charge indicate a cell to be lower than any others.

d.   Warpage or buckling of plates or insulators is evident.

WARNING:

Battery fluid is poisonous and dangerous, causing severe burns, etc. Contains sulfuric acid. Avoid contact with skin, eyes or clothing.

Antidote:

EXTERNAL-FLUSH with water.

INTERNAL-Drink large quantities of water or milk. Follow with milk of magnesia, beaten egg or vegetable oil. Call physician immediately.

Eyes: Flush with water for 15 minutes and get prompt medical attention.

Batteries produce explosive gases. Keep sparks, flame, cigarettes, etc., away. Ventilate when charging or using in enclosed space. Always shield eyes when working near batteries.

KEEP OUT OF REACH OF CHILDREN.

2.    The service life of a battery is usually 2 to 3 years, but lack of care as described below will shorten the life of the battery.

a.   Negligence in keeping battery topped off with distilled water.

b.   Battery being left discharged.

c.   Over-charging with heavy charge.

d.   Freezing.

e.   Filling with water or sulfuric acid containing impurities.

f.    Improper charging voltage or current on new battery.

3.    If the motorcycle is not to be used for a long time, remove the battery and have it stored. The following instructions should be observed:

a.   Recharge the battery periodically.

b.   Store the battery in a cool, dry place.

c.    Recharge the battery before reinstallation.

Battery	12N12A-4A-1
Electrolyte	Specific gravity: 1.280
Initial charging current	1.2 amp for 10 hours (new battery)
Recharging current	10 hours (or until specific gravity reaches 1.280)
Refill fluid	Distilled water (to maximum level line)
Refill period	Check once per month (or more often, required)