TDM900 : Checking the electrical system

What you need : a digital or analog multimeter (voltmeter & ohmmeter).
Checking conditions :
• ambient temperature 20°C unless otherwise noted.
• 10% tolerance precision on voltmeter & ohmmeter.
• use a quality ohmeter to check low resistance values (below 10 Ω), standard ohmeter are not reliable enough.

Locating elements

Non-ABS models

(image)1 - Wire harness
2 - Ignition coil
3 - Front brake light switch
4 - Clutch switch
5 - Starter relay
6 - Fuse box
7 - Battery
8 - Neutral switch
9 - Sidestand switch
10 - Rear brake light switch
11 - Oil level switch
12 - Radiator fan motor
13 - Horn

(image)1 - Coolant temperature sensor
2 - Atomospheric pressure sensor
3 - Intake air tempreture sensor
4 - Intake air pressure sensor
5 - Lean angle cut-off switch
6 - Turn signal relay
7 - Fuel injection system relay
8 - Radiator fan motor relay
9 - Starting circuit cut-off relay
10 - Speed sensor
11 - O2 sensor
12 - Crankshaft position sensor
13 - Cylinder identification sensor
14 - ECU

ABS models (TDM900A)

(image)1. Wire harness
2. Ignition coil
3. Front brake light switch
4. Clutch switch
5. Fail safe relay
6. Starter relay
7. Fuse box
8. Battery
9. Neutral switch
10. Sidestand switch
11. Rear brake light switch
12. Oil level switch
13. Radiator fan motor
14. ECU (ABS)
15. Horn

(image)1. Coolant temperature sensor
2. Atomospheric pressure sensor
3. Intake air tempreture sensor
4. Intake air pressure sensor
5. Lean angle cut-off switch
6. Turn signal relay
7. Fuel injection system relay
8. Radiator fan motor relay
9. Rear wheel sensor
10. Starting circuit cut-off relay
11. Speed sensor
12. O2 sensor
13. Crankshaft position sensor
14. Front wheel sensor
15. Cylinder identification sensor
16. ECU

Charging system

(image)(2) Generator
(3) Rectifier
(4) Main fuse
(5) Battery

First of all check connectors, wiring and the main fuse with the ohmmeter.

Battery check

• Disconnect the battery (negative plug first).
• Check battery voltage (voltmeter DC 20V).
• Minimum open-circuit voltage should be 12.8V maximum, 11.5V minimum.
• Below 12.8V, the battery needs to be charged according to the following diagram :

(image)V : Battery voltage
T : Charging time required (@ 1A)

Charging voltage and rectifier check

• Connect the battery (positive plug first).
• Start the engine and let it run at 5000 rpm.
• Measure the charging voltage : 14V @ 5000 rpm.
• In case voltage is unstable or above 15V : rectifier is dead.

Never disconnect the battery when engine is running.

Generator check

• Remove the casing of the generator.
• Disconnect the connector with three white wires.
• Check the resistance of the windings :

(image)Coil resistance : 0.18 à 0.28 Ω between (1)-(2), (1)-(3) and (2)-(3).
Please note : only a quality ohmeter may check such low values.

• Check also the resistance between each connector and the chassis : a short-circuit or an infinite resistance means the generator is dead.
• In case an inductance-meter (LCmeter) is available, check each coil :
- stator still inside the engine, up to 100mH.
- stator fully removed, around 50-55mh.

Ignition - starting circuit

• Check all connectors and wiring on the ignition line.
• Check the fuses, main switch, engine kill switch and engine cut-off relay.
• Check the side-stand switch.
• Check the crankshaft position sensor and tilt sensor through DIAG mode.

Spark-plugs check

• Remove the spark-plugs.
• Measure the electrodes gap : 0.8 ~ 0.9mm.
• Spark-plugs reference is : DPR8EA-9 (NGK) / X24EPR-U9 (DENSO).
• Connect the spark-plugs to the spark-plug caps and ground.
• Check sparks through the DIAG mode.

Spark-plug caps check

• Disconnect the spark-plug caps.
• Measure the resistance :

(image)Caps resistance : 10 KΩ.

Ignition coils check

• Disconnect the ignition coils.
• Measure the coil resistance :

(image)Primary coil resistance : 3.4 ~ 4.6 Ω.

(image)Secondary coil resistance : 10.4 ~ 15.6 KΩ.

Starter solenoid check

In case a series of clicks from the solenoid is heard at startup : battery voltage is too low, charge or replace.

(image)• Disconnect solenoid.
• Connect battery at (1) and (2).
• Check continuity at (3) et (4).

Cooling system

• Check battery voltage.
• Check cooling system fuse.
• Check relay and radiator fan motor through the DIAG mode.

Engine coolant temperature sensor check (ECT)

• Remove the coolant temperature sensor from the thermostat assembly.
• Connect the coolant temperature sensor to the ohmmeter.

(image)• Immerse the coolant temperature sensor in a container filled with coolant.
• Slowly heat the coolant, then measure resistance at corresponding temperature.

(image)• Resistance @ 20°C : 2.32 ~ 2.59 KΩ.
• Resistance @ 80°C : 310 ~ 330 Ω.
• Resistance @ 110°C : 140 ~ 150 Ω.

• Replace the coolant temperature sensor on the thermostat assembly at 20Nm (2.0 mkg) with bond Sealock.

Fuel injection system


There are two kinds of sensors:
• Active sensors (3 wires). - they deliver a variable voltage and should be connected to the ECU before checking, the main switch must be switched On. These sensors are either Hall effect sensors (speed sensor, cylinder identification sensor, pressure sensors, lean angle sensor) or a simple potentiometer (TPS). Use a voltmeter to check them.
• Passive sensors (2 wires). These are either variable resistors (temperature sensors) or coils (crankshaft position sensor). They may be checked after being disconnected from the ECU, with an ohmmeter.
• The O2 sensor is another kind of sensor : this is a two wires voltage generator.

Accessing the connectors of the sensors is sometime a difficult matter. An alternative method is to use the main ECU connector as all sensors are connected to it (except the fuel gauge). Refer to the wiring diagram for the wires colour.

Caution : all sensors are fragile and costy pieces of equipment, handle with care.

First to do

• Check battery voltage.
• Check fuel injection system fuse.
• Check the main switch and the engine kill switch.
• Check the sensors, the injection system relay, the injectors and the fuel pump through the DIAG mode.
• In case the DIAG mode fails to give correct results, check the sensors as described below.

Fuel pump and fuel gauge check

• Locate fuel pump and fuel gauge connectors under the fuel tank.
• Disconnect the fuel pump (green connector, red/blue and black wires).
• Disconnect the fuel gauge (white connector, black/white and green wires).
• Measure the resistance :

(image)• Fuel pump resistance (1) & (2) : 0.2 ~ 3.0 Ω.
• Fuel gauge resistance (3) & (4) :
• 19 ~ 21 Ω (full tank).
• 139 ~ 141 Ω (empty tank).

• In case of a disconnected or defective fuel gauge the whole fuel level display (six bricks) starts blinking.

Crankshaft position sensor check

• Locate the sensor near the generator.
• Disconnect the sensor (blue/yellow and green/white).
• Measure the resistance : 420 ~ 569 Ω.

Cylinder identification sensor check

• Locate the sensor on the engine head.
• Connect the voltmeter : (+) on white wire and (-) on black/blue wire).
• Switch main switch on.
• Measure the voltage : 4.8 V (sensor on) or 0.6 V (sensor off).
• In case of malfunction the sensor may be replaced by the speed sensor (same part, direct swap).

Speed sensor check

• Locate the sensor under the sprocket cover.
• Connect the voltmeter : (+) on white/yellow wire and (-) on black/blue wire).
• Switch main switch on.
• Measure the voltage : 4.8 V (sensor on) or 0.6 V (sensor off) - rotate the rear wheel...
• The speed sensor is not a vital element on the bike. In case of malfunction (dead sensor or open-circuit) the ECU will not display any error code but there will be no speed info on the speedometer.
• the speed sensor is the same as the cylinder identification sensor. In case the latter is defective, it may be replaced by the speed sensor as a temporary fix.

Intake air temperature sensor check (IAT)

• Locate the sensor on the bottom side of the air-filter box.
• Disconnect the sensor (brown/white and black/blue).
• Measure the resistance : ~ 2.4 KΩ @ 20°C.
• The 2007 edition of the Workshop Manual gives different electrical characteristics for both temperature sensors (IAT & ECT). This is wrong, they are actually the same parts, as indicated inside the 2002 Workshop Manual.

Intake air pressure sensor check

• Locate the sensor on the fuel injection rail, beside the fuel pressure regulator.
• Connect the voltmeter : (+) on pink/white wire and (-) on black/blue wire).
• Switch main switch on.
• Measure the voltage : 3.75 ~ 4.25 V.

Atmospheric pressure sensor check

• Locate the sensor on the right side of the main fuse.
• Connect the voltmeter : (+) on pink wire and (-) on black/blue wire).
• Switch main switch on.
• Measure the voltage : 3.75 ~ 4.25 V.

Throttle position sensor check (TPS)

(image)• Locate the sensor on the left-hand injector body.
• Disconnect the sensor.

(image)• Check the resistance value :
Pins (1) et (2) : 4.0 ~ 6.0 KΩ.
Pins (3) et (2) : While slowly opening the throttle, check that the throttle position sensor resistance is within the specified range : 520 ~ 900 Ω minimum up to 4.0 ~ 6.0 KΩ maximum.
Please note that some TPS have a maximum resistance of around 3KΩ. This has no consequences for the ECU.

(image)• Reconnect the sensor.
• Switch main switch on.
• Check the voltage :
Pins (1) & (2) : 4.95 ~ 5.05 V.
Pins (3) & (2) : 0.53 ~ 0.83 V (at idle).

In case the measured voltage isn't within the specified range, adjust the sensor position angle :

(image)• Loosen slightly both screws (4).
• Adjuste sensor position until voltage is within the specified range : 0.53 ~ 0.83 V (at iddle).
• Tighten the screws.

Check also the page about the TPS issues.

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