J
Jack Klarich
Guest
If Harley-Davidson speedometer reads ‘BUS Er’ with the ignition key switch turned ON (engine stop switch at RUN with the engine off), check serial data line for an open or short to ground between diagnostic link [91A] terminal 3 and ICM connector terminal 12. Check for an open diagnostic test terminal between diagnostic link connector terminal 3 and ICM. With ignition key switch turned ON, transmit data should be typically 0.6-0.8 volts. The range of acceptable operation of the serial data line is 0-7.0 volts. For a quick check of speedometer function, a ‘wow’ test can be performed. Press and hold odometer reset switch then turn ignition switch ON. Release reset switch. Background lighting should illuminate, gauge needles should sweep their full range of motion, and check engine, battery and security indicator lamps should illuminate. The security lamp may illuminate even if the vehicle is not equipped with a security system. If instrument module fails ‘wow’ test, check for battery, ground, ignition and accessory wiring to speedometer.
Harley-Davidson engine cranks but will not start – Is there fresh fuel in tank? Are spark plug wires firmly connected to coil terminals? YES to both then – Check for continuity to ground at breakout box terminal 7 (black). Wiggle harness during continuity check. Check for battery voltage at breakout box terminal 5 (black) while wiggling harness. Check the condition of the battery. Perform a voltage test and recharge if below 12.60V. Check battery connections and perform load test – If it fails replace the battery. Remove spark plug cable from spark plug. Visually check condition of plug. Attach cable to SPARK TESTER – Clip tester to cylinder head bolt. While cranking engine, look for spark. Repeat procedure on other spark plug cable. If NO spark check the resistance of each spark plug cable that did not fire the spark tester. Also check for faulty plug wire connections and wire boots for carbon tracking.
Spark will not be present when cranking with both spark plugs removed. When checking for spark, use SPARK TESTER with both spark plugs installed and one spark plug wire connected to spark tester. Reinstall spark plug cable and repeat procedure on other spark plug cable. Perform spark plug cable resistance test. Remove spark plug cable from spark plug and ignition coil. For best results, use a needle nose pliers for removal/installation on coil. Gently grasp cable as close to terminals as possible. Using an ohmmeter, touch probes to terminals on each end of plug wire. Reinstall and repeat procedure on other spark plug cable. This test can also be performed by substituting a known good coil for one causing the no spark condition. The coil does not require full installation to be functional.
The manifold absolute pressure sensor is supplied 5 volts from the ignition control module and sends a signal back to the ignition control module. This signal varies in accordance with engine vacuum and atmospheric barometric pressure. Changes in barometric pressure are influenced by weather and altitude. With the MAP sensor disconnected, the ignition control module should recognize a low voltage. If low voltage is observed, the ignition control module and harness are not at fault. Gently place a jumper wire across MAP Sensor connector terminals B and C using HARNESS CONNECOR TEST KIT, gray male probes and patch cord. With the jumper in place, the ignition control module should recognize a high voltage. MAP sensor output check. Using the VACUUM PUMP, apply a vacuum to the pressure port of the MAP sensor. The signal voltage should lower as the vacuum is applied.
Crank Position Sensor: DTC P0371, P0372, P0374 – Check for intermittent connection, pinched or damaged wires, and loose CKP sensor fastener. Conditions found? Connect Breakout Box to harness only, leaving ignition control module disconnected. Measure resistance between terminal 8 and terminal 5 (black) on Breakout Box and terminal 9 (black) and terminal 5 of (black) on Breakout Box. Is resistance more than 1 megohm? NO – Connect DVOM to Terminals 8 and 9 at connector on Breakout Box. Set DVOM to AC volts and crank engine. Does DVOM read 1 VAC minimum during cranking? YES – Repairs are necessary.
Ignition Coil – Ignition coil DTCs will set if the ignition coil primary voltage is out of range.This could occur if there is an open coil or loss of power to the coil. If front and rear DTCs are set simultaneously, it is likely a coil power failure or a coil failure has occurred. The coil receives power from the engine run/stop switch. The ignition control module is responsible for turning on the coils by providing the ground to activate the coils, which in turn powers the coils.
The initial Harley-Davidson diagnostic check is an organized approach to identifying a problem caused by an electronic control system malfunction. If no problems are found after completion of the initial diagnostic check, a comparison of running parameters may be used to help locate intermittents and out-of-specification sensors. If still NO conditions are found, and the engine won’t run. Then it may be mechanical failure – Things to check then would be compression, cam timing, and the fuel system. NOTE: Cranking the engine with test lamp in place of the ignition coil can sometimes cause a DTC P1351 or P1352 to be set. This condition is normal and does not by itself indicate a malfunction. Clear DTCs
Harley-Davidson engine cranks but will not start – Is there fresh fuel in tank? Are spark plug wires firmly connected to coil terminals? YES to both then – Check for continuity to ground at breakout box terminal 7 (black). Wiggle harness during continuity check. Check for battery voltage at breakout box terminal 5 (black) while wiggling harness. Check the condition of the battery. Perform a voltage test and recharge if below 12.60V. Check battery connections and perform load test – If it fails replace the battery. Remove spark plug cable from spark plug. Visually check condition of plug. Attach cable to SPARK TESTER – Clip tester to cylinder head bolt. While cranking engine, look for spark. Repeat procedure on other spark plug cable. If NO spark check the resistance of each spark plug cable that did not fire the spark tester. Also check for faulty plug wire connections and wire boots for carbon tracking.
Spark will not be present when cranking with both spark plugs removed. When checking for spark, use SPARK TESTER with both spark plugs installed and one spark plug wire connected to spark tester. Reinstall spark plug cable and repeat procedure on other spark plug cable. Perform spark plug cable resistance test. Remove spark plug cable from spark plug and ignition coil. For best results, use a needle nose pliers for removal/installation on coil. Gently grasp cable as close to terminals as possible. Using an ohmmeter, touch probes to terminals on each end of plug wire. Reinstall and repeat procedure on other spark plug cable. This test can also be performed by substituting a known good coil for one causing the no spark condition. The coil does not require full installation to be functional.
The manifold absolute pressure sensor is supplied 5 volts from the ignition control module and sends a signal back to the ignition control module. This signal varies in accordance with engine vacuum and atmospheric barometric pressure. Changes in barometric pressure are influenced by weather and altitude. With the MAP sensor disconnected, the ignition control module should recognize a low voltage. If low voltage is observed, the ignition control module and harness are not at fault. Gently place a jumper wire across MAP Sensor connector terminals B and C using HARNESS CONNECOR TEST KIT, gray male probes and patch cord. With the jumper in place, the ignition control module should recognize a high voltage. MAP sensor output check. Using the VACUUM PUMP, apply a vacuum to the pressure port of the MAP sensor. The signal voltage should lower as the vacuum is applied.
Crank Position Sensor: DTC P0371, P0372, P0374 – Check for intermittent connection, pinched or damaged wires, and loose CKP sensor fastener. Conditions found? Connect Breakout Box to harness only, leaving ignition control module disconnected. Measure resistance between terminal 8 and terminal 5 (black) on Breakout Box and terminal 9 (black) and terminal 5 of (black) on Breakout Box. Is resistance more than 1 megohm? NO – Connect DVOM to Terminals 8 and 9 at connector on Breakout Box. Set DVOM to AC volts and crank engine. Does DVOM read 1 VAC minimum during cranking? YES – Repairs are necessary.
Ignition Coil – Ignition coil DTCs will set if the ignition coil primary voltage is out of range.This could occur if there is an open coil or loss of power to the coil. If front and rear DTCs are set simultaneously, it is likely a coil power failure or a coil failure has occurred. The coil receives power from the engine run/stop switch. The ignition control module is responsible for turning on the coils by providing the ground to activate the coils, which in turn powers the coils.
The initial Harley-Davidson diagnostic check is an organized approach to identifying a problem caused by an electronic control system malfunction. If no problems are found after completion of the initial diagnostic check, a comparison of running parameters may be used to help locate intermittents and out-of-specification sensors. If still NO conditions are found, and the engine won’t run. Then it may be mechanical failure – Things to check then would be compression, cam timing, and the fuel system. NOTE: Cranking the engine with test lamp in place of the ignition coil can sometimes cause a DTC P1351 or P1352 to be set. This condition is normal and does not by itself indicate a malfunction. Clear DTCs
