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IH: Electrical System


FUSES, RELAYS, CHARGING SYSTEM

Be sure to review the basic Electrical Concepts in the Reference Section, especially wire gauging.

The Circuit Breakers (CB) used on Sportsters are of the self-resetting type. Once they break contact, they will automatically reset after a period of time. These breakers function based on a bi-metallic strip that is heated by current flowing through the strip. More current will cause more heat.

If the rated amperage for the CB is exceeded, the strip will be overheated, causing it to bend away from the internal contact, thereby opening the circuit and removing the current flow. Once the bi-metallic strip has cooled sufficiently, it will return from its heated position and once again make contact. This will allow the current to begin flowing again. If the circuit is still drawing excessive current, the CB will repeat the open & close cycling until the current level is reduced below the current rating and no longer causing the bi-metallic strip to overheat.

Although very reliable, over time & usage, the CB may no longer function at the rated current, requiring replacement of the Circuit Breaker.

The following quotation makes the point that fuses are often slow to react to overcurrent situations. It is critical to replace rated fuses with the same rating in order to properly protect the circuits.

First, fuse ratings can be a bit misleading. A 10A ATO (automotive) fuse will conduct 11 amps for 100 hours minimum. At 13.5 Amps a 10A ATO fuse can take as long as 10 minutes to blow. It is not like once you draw 10 amps “poof” the fuse is gone. (From FUSE SIZING PRIMER located at http://www.powerlet.com/learningCenter/fuseSizing)


  • A 2“ long 20 gauge wire (70105-73) was added on FL,FLH, FX, FXE, XL and XLCH models to act as a fuse-able link. The fuse wire protects wiring between the battery and the lighting, ignition and accessory circuit breakers. In place of this HD part, any 20 gauge braided wire will work also. But, don't use any heavier gauge wire. The opposing wiring is heavier gauge so this fuse-able link acts as the weakest conductor in the circuit. 1)
    • On Xl, the wire is connected between the regulator “BAT” terminal and the red wire connector in conduit leading to the starter solenoid (long) terminal.
    • On XLCH, the wire was connected to the battery ”+“ terminal and to the red wire connector in conduit leading to the regulator “B+” terminal.
  • Before replacing the fuse wire, check for shorts in the wiring or the ignition switch to determine the cause of the burnout.


Generator

Sub Documents

13 Amp Generator 1982 →

  • New 13 amp generators were used in 1982 produc­tion XLs featuring thrust washers (4 thicknesses to adjust armature endplay from .004“-0.010”) between the rear end cover and rear ball bearing. 2)
  • After engine VIN (1HD1CAH1XCY111183) the torque spec was lowered for the armature gear shaft nut at the oil separator washer to 6-8 ft/lbs in order to prevent bowing of the oil separator washer (which can lead to generator noise). Engines exhibiting unusual generator 'whistling' should be checked for this condition. If the washer is found to be deformed it must be replaced. 3)
  • This generator can be retrofitted to 1965 models with some guidelines for retrofitting: 4)
  1. A new voltage regulator (74504-82) must also be used to realize the full 13 amp output.
  2. A new style drive gear (31073-63A) must be used.
    • The internal spline of the old style drive gear will not properly match the spline on the new armature shaft.
  • Do not use the new style voltage regulator (74504-82) with a 10 amp generator, component damage can result.

See these XLForum Threads regarding Generator Operation & Testing:
http://xlforum.net/forums/showthread.php?t=39146
http://xlforum.net/forums/showthread.php?t=559976


Starter Relay

1974-1979 Starter Relay

In some cases, the starter relay used on 1974 to 1979 1200, 1340 and 1000cc models may develop corroded contacts because of moisture under wet road conditions. 5)

Testing

  • Using a 12 volt test light, ground one of the leads and touch the other lead to each large relay terminal.
    • With ignition switch “on”, one of the terminals should light test lamp.
    • When starter button is depressed, the relay should operate and the other large terminal should light the test lamp.
  • If lamp does not light, touch test lamp lead to small relay terminal with starter button depressed. If lamp lights, relay is defective and must be replaced. If relay does not light, control circuit from starter button to relay is faulty and must be checked for continuity.

Installation

  • Caution, before removing the relay, disconnect the battery.
  • Before installing the relay (71463- 73), dip the base of relay in insulating paint or apply with a brush (sealing agent such as GE Glyptal insulating paint) to ensure a good gasket joint seal. This paint (No. 1201 Red Enamel) is available in one quart cans from General Electric distributors.
  • The relay is mounted by 2 screws below the battery carrier.
  • When reinstalling relay, add two shake­ proof washers between base plate and battery carrier to provide a good grounding circuit.
  • Reconnect the wiring to the relay and the battery and check starter operation.



1)
HD Service Bulletin #659 dated March 6, 1974 pg 1
2)
HD Service Bulletin #M-837 dated October 2, 1981
3) , 4)
HD Service Bulletin #M-840 dated October 2, 1981
5)
HD Service Bulletin #M-763 dated December 21, 1979
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