Buell Blast 2014 Service Manual page 338

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The ignition module contains all the solid-state components
used in the ignition system. The dwell time is fixed. The igni-
tion module has added protection against transient voltages,
continuous reverse voltage protection and damage due to
jump starts. The system will operate down to 6.0 VDC. The
ignition module is fully enclosed to protect it from vibration,
dust, water and oil. The module is not repairable. Replace the
unit if it fails.
The ignition module is programmed with two spark advance
curves to meet varying engine loads. The ignition module
selects the proper curve based on TP sensor output voltage
which is continuously monitored. This system ensures correct
timing to suit starting and high-speed requirements.
A single ignition coil fires the spark plug at the end of the
compression stroke (no waste spark), thereby igniting the air/
fuel mixture.
Throttle Position Sensor (TP Sensor) and
Auto-Enrichener
The throttle position sensor (TP Sensor) is attached to the
throttle shaft on the carburetor. The TP sensor voltage is high
when the throttle is opening during acceleration and under
high engine load conditions and the voltage is low during
deceleration and under low engine load conditions. The high
or low voltage signal from the TP sensor is communicated to
the ignition module which selects the correct spark advance
curve (change between high and low curve takes place at TP
Sensor input 2.4V).
The low voltage signal curve (throttle less than 1/2 open,
<2.4V TP Sensor input), selected for maximum spark
advance under normal light-load cruising conditions, provides
improved fuel economy and performance. The high voltage
signal curve (throttle more than 1/2 open, >2.4V TP Sensor
input) minimizes spark knock while maintaining performance
under high-load conditions (acceleration and highway driv-
ing).
The auto-enrichener is located on the carburetor and controls
the cold idle speed of the motorcycle and enriches the air/fuel
mixture. The auto-enrichener circuit is grounded and opera-
tive for 2-5 minutes after the motorcycle is started. The
ground is completed by the ignition module.
Bank Angle Sensor
The bank angle sensor provides input to the ignition module
on whether or not the vehicle lean angle is greater than 55
degrees. If vehicle lean angle exceeds 55 degrees, the bank
angle sensor will shut off power to the ignition.
Rotor and Cam Position Sensor
The rotor and cam position sensor (cam position sensor is
integrated with the ignition module) are located in the gear-
case cover on the right side of the motorcycle. The rotor is
mounted on the camshaft and operates at one-half crankshaft
speed. As the rotor turns, a slot in its outside diameter breaks
the magnetic field of a Hall-effect device mounted on the cam
position sensor. The output of the Hall-effect device is a logic-
type signal that corresponds to the timing information from
the spinning rotor. This technique gives accurate timing infor-
mation down to "0" speed.
The ignition system produces a spark near top dead center
(TDC) for starting. At RPM's and loads above this, the system
produces a spark 0˚-45˚ before TDC. The whole timing pro-
gram can be shifted by mechanical rotation of the integrated
7-4 2004 Buell P3: Electrical
ignition module plate. See 1.20 IGNITION TIMING AND IDLE
SPEED ADJUSTMENT.
See the wiring diagrams at the end of this section for addi-
tional information on ignition system circuits.
TROUBLESHOOTING
For poor performance, poor fuel economy or excessive ping-
ing, see DRIVABILITY TROUBLESHOOTING on Page 7-10.
Also refer to Table 4-1 in Section 4 for Fuel System Trouble-
shooting.
For incorrect idle speed, see DRIVABILITY TROUBLE-
SHOOTING on page 7-15.
If the engine will not start, or if hard starting or missing indi-
cates a faulty operating ignition system, perform the tests
listed below.
Check for Ignition Spark
1. Remove seat and fuel tank. See Sections 2 and 4.
2. Disconnect spark plug cable from spark plug. Check
condition of plug and cable. Clean or replace as neces-
sary. See 7.10 SPARK PLUG
3. Install SPARK PLUG TESTER (HD-26792) to spark plug
cable end.
4. Turn ignition key switch to IGN and engine stop switch
to ON and pull in clutch lever.
5. With transmission in neutral, press electric starter button.
Check for a spark across plug electrode gap.
a. If a spark is produced, problem is not in electronic
system or coil. Check carburetion, enrichener and
spark plug.
b. If no spark is produced, check battery voltage and
battery connection. Battery voltage must be at least
12.6 VDC. Charge battery if voltage is low.
6. Verify that the ground strap from the front isolator to the
frame is in good condition. If there is still no spark, then
perform the tests under
No Ignition Spark
See Figure 7-2. To conduct the following tests, it will be nec-
essary to assemble a set of jumper wires.
Cut two wires of ample length to reach from a good ground
connection to the negative terminal of the coil primary. If a
suitable capacitor is not available, use a condenser (such as
the type used in earlier breaker point ignition systems).
When conducting Step 5 of the previous spark tests, use the
SPARK PLUG TESTER (HD-26972). During the testing pro-
cedures, check for spark across the spark plug electrodes.
0.33 MFD capacitor
Figure 7-2. Test Jumper
CABLE.
NO IGNITION SPARK.
a0218x7x
16 ga. wire