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Fault finding - Fault finding charts62C
ALP 10 Inefficient rear screen de-icing/demisting
NOTESCarry out this conformity check after a full check using the diagnostic tool (fault
reading, especially UCH and injection faults and configuration checks).
Check that the fuses are sound.
Use a multimeter and a 21 W test light.
Use the Wiring Diagram Technical Note, New Twingo.
Special notes:
Check that the inside of the windows are not greasy as this reduces the efficiency of
the de-icing.
Note:
The de-icing control is only authorised when the engine is running to save
power. The rear screen de-icer is controlled by pressing the rear screen de-icer
button (with time delay and rear-view mirror de-icer if fitted).
Ensure that there are no water leaks in the passenger compartment which would significantly increase the
moisture and reduce the effectiveness of the demisting function (see ALP 12 if the fault is noted).
Is the fault still present?
YES NO
Check that the UCH receives the signal about the
status and operation of the engine. In the Cold Loop
screen, status ET142 Engine operating phase
should display RUNNING.
Is status ET142 RUNNING?
YES
End of fault finding procedure.
NOCarry out fault finding on the UCH
(interpretation of status ET142) and on the
multiplex network.
AFTER REPAIRCarry out a complete check with the diagnostic tool.
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Fault finding - Fault finding charts62C
ALP 10
CONTINUED
Press the de-icing button on the control panel and
check status:
–ET028 Heated rear screen button
Does status ET028 display PRESSED?
YES
Connect a test light between connections 15LP and
MYH of component 200 and, using the diagnostic
tool, run command AC060 Rear screen de-icer
(UCH command mode menu).
Does the test light illuminate?
YES
Connect a test light between connection 15LP and
the chassis earth and use the diagnostic tool to
run command AC060 Rear screen de-icer (UCH
command mode menu).
Does the test light illuminate?
NO
Check the continuity of connection 15LP between
components 200 and 645.
Is the continuity correct?
YES
See 87B, UCH, Interpretation of commands, for command AC060 Rear screen de-icer.
NOContinuity fault on connection 15M.
Using an ohmmeter, carry out a continuity
test on connection 15M between
components 319 and 645. If there is a
procedure (see Technical Note 6015A,
Repairing electrical wiring, Wiring:
Precautions for repair), repair the wiring,
otherwise replace the wiring.
NOCheck the resistance of the rear screen
de-icer lines. The line resistance must not
be zero or infinite. If the resistance is not
correct, replace the rear screen (see MR
412, Bodywork, 54A, W indows, Rear
screen window: Removal - Refitting).
YESContinuity fault on connection MYH of
component 200. If there is a repair method
(see Technical Note 6015A, Repairing
electrical wiring, Wiring: Precautions
for repair), repair the wiring, otherwise
replace the wiring.
NOContinuity fault on connection 15LP
between components 200 and 645. If
there is a repair method (see Technical
Note 6015A, Repairing electrical wiring,
Wiring: Precautions for repair), repair
the wiring, if not replace the wiring.
AFTER REPAIRCarry out a complete check with the diagnostic tool.
