Autodata - Diagnostic Trouble Codes Fault locations and probable causes - 2004 edition

Tools & equipment
Resistance and continuity checking - Fig. 7, Fig. 8, Fig. 9 & Fig. 10
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High resistance in earth connections can cause unusual
(and apparently illogical) symptoms that are seemingly
unconnected with the components involved.
Earth connections should be thoroughly cleaned and
treated with a proprietary contact cleaner before
assembly.
Connections in the vicinity of the battery are particularly
vulnerable to corrosion.
Earth wires should be checked along their whole length for
chafing, corrosion and mechanical damage. A typical
earth wire may have 20-30 strands and although there will
still be a connection if only a few of these are intact, the
resulting high resistance will cause problems.
Suspect multi-plugs should be 'dismantled' (if possible)
and the terminals thoroughly inspected and cleaned.
Set the meter to RESISTANCE.
If applicable, set the meter to the correct scale (most
modern meters are self-ranging).
Connect the black test lead to the red test lead and check
that the meter displays ZERO R.
Fig. 6
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NOTE: If ZERO R is not displayed, refer to the meter operating instructions.
Disconnect the component from any wiring.
Connect the black test lead to one terminal being tested.
Connect the red test lead to the other terminal being tested.
Read and record the value displayed.
If the meter displays ZERO,
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Fig. 7 this indicates continuity.
If the meter displays a (infinity) Fig. 8, this indicates NO continuity (open circuit).
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Checking signal voltage between wire and earth -
component multi-plug connected
Fig. 7
-
Fig. 8
Circuit continuity
Open circuit
Fig. 9
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Fig. 10
AD52755
Checking component resistance
Checking earth connection at harness multi-plug
[Autodata f Tools & equ~prnent
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