Volvo 819 E - Page 65

Gro up 28 Ignit ion sys t ems
D esign and function - System descript i ons
Functional test program
The system m oni tors the operat io n of certain compo nent s and swi lches by opera tion of the items in question . When
the co mponent or switch is operated in accordance with a set procedure, the LED displays a 3-digit code in confirma-
tion . Fa i lure to display a co de indicates that the con trol unit has fa iled to detect operation of the co mponen t/ sw itch.
In th
is event, the fault may tie either in the item itself , or in the associated wiring and connections .
The
funct ional test program provides an ideal means of checking that the switches are correc tly wired e.g. on com-
plet
ion of repa ir wor1t on Ihe engine. As an example. it may be used to check whether the speed/position pick-up andJ
or wiring is in tact if the engine fails 10 slart .
Some major differences
The EZ - 116K1Rex-1 diagnostic system differs from other EZ -K systems in the following respects when used to per -
form the same type of faull traci ng :
- The use
of a test diode is unne cessary. This has been superseded by the diagnostic unit which , in effect, is an ex-
tension
of Ihe ignition syst em .
- T
he engine must be switched off during fautt tracing.
-
Si n ce the diagnostic system can dis play a greater number of faull codes, it covers a wider range of po tential fau lt s,
enabling them 10 be identified mo re quickl y.
- The system includes a 'fault-free' code.
-
All fault codes are of Ihe 3-digit type.
- The
lechnician decides when the nexi faull code is to be displayed.
- T
he system includes a functional test program , providing a fasl and reliable means of checking that certain switch -
es have been reconnected correctly following re pair work on the engine.
-
Switching off the ignition and Slopping the engine is not sufficienllO erase the memory . In this case, the memory
can be erased on completion of work only by operaling the pushbutton in a predeterm i ned sequence.
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