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Checking
- Start engine and let idle.
- Switch A/C on, push "AUTO" button, set
temperature to "LO" and blower speed to "HI".
A/C compressor symbol must light up and
A/C must run.
- Using VAG 1551 scan tool, select "Basic
Setting" function 04, display group 004 page 01
-150
.
A/C compressor must stop (visual check)
If the A/C compressor does not shut off:
- Switch A/C off (press "minus" button for fresh air
blower in A/C control head repeatedly, until all
indicators are off).
Continue to let engine run in idle.
- Using VAG 1551 scan tool, select "Read
Measuring Value Block" function 08, display
group 004.
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24-96
- Switch Fluke 83 multimeter to voltage
measurement range and connect between
signal wire (trip computer 20-pin connector) and
Ground (GND), using wiring diagram.
- Start engine and let idle.
Specified value: approx. 0.3 to 0.6 volts,
corresponding to engine speed (RPM)
- Vary engine speed continuously from 1000 to
4000 RPM.
Specified value: approx. 0.3 to 0.6 volts,
corresponding to engine speed (RPM)
If the specified value is not obtained, even
though the trip computer shows no consumption
value or there is a stored malfunction in the
TCM:
- Stop engine (switch ignition off).
- Replace trip computer and/or TCM as
required.
If the specified value is not obtained:
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