Webasto Thermo Top V Workshop Manual - Troubleshooting
Troubleshooting
Thermo Top V
502
Functional analysis of heater and its components
No. System
Component
Test/Measure/Parameter
1.
Power supply
Measure supply voltage under load at heater connector X2
≥
11.5 V,
see section 5.2.2 (Undervoltage switch-off)
2.
Clock
Press Flame button; display lighting must light up
Test W bus signal on Pin 2 on heater connector X1 with an LED lamp against “+”
(LED flickers when button is pressed)
3.
Receiver (Telestart T80 and
T91)
On 6-pin connector on receiver, test W bus signal on Pin 2 with an LED lamp
against Pin 1 “+” (LED flickers when On button is pressed)
4.
Transmitter (Telestart)
Assign/teach transmitter as described in instructions for receiver
Test operating mode on Telestart hand-held transmitter (heat/ventilate)
Battery of hand-held transmitter should have sufficient capacity (new)
5.
Metering pump
Test continuity from connector X1, Pin 5 to connector X7 (blue)
Test continuity from connector X7 (brown) against earth
Test resistance of the metering pump at +20 °C = 5.2 ohms
±
5 %
as described
in section 8.6.2.2
Measure delivery rate with Webasto Thermo Test PC Diagnosis as described in
section 8.6.2.2
- Petrol: 34 to 42 ml in 180 sec. at 7 Hz.
- Diesel: 36 to 44 ml in 180 sec. at 7 Hz.
Test connection of fuel line on connection piece
as described in section 8.6.2.1
6.
Glow plug
Measure glow plug resistance value on glow plug connector X3 (white wire)
as
described in section 6.3.1.4.
At 24
±
6 °C: 0.200 to 0.300 ohms.
7.
Fuel preheating
Test resistance of fuel preheating on connector X6, 4-pin (black wire) as described
in section 6.3.1.2 for Variant 1 or 2
8.
Solenoid valve (if present)
Testing of solenoid valve as described in section 6.3.1.3.
At 20
±
5 °C: 145
±
9 ohms.
9.
Temperature sensor
Test sensors as described in section 6.3.1.5
Coolant temperature sensor G1, blue wire, at 20
±
6 °C:
min. 1,988, max. 4,050 ohms.
Overheating sensor G2: Red wire, at 20
±
6 °C: max. 250 ohms.
10.
Combustion air fan
Test operation of fan motor with Webasto Thermo Test PC Diagnosis component
test
Checking of CO
2
setting as described in section 6.2.2
11.
Circulating pump
Test resistance and installation as described in section 8.6.1: 10
±
1 kohms
Test operation with Webasto Thermo Test PC Diagnosis component test
12.
Fuel connection
Fuel visible in line?
Air
Bubbles
in fuel line?
If there is, then change connection or routing of line!
Check connection in vehicle fuel system (also see section 8.6.2.1).
Ensure sufficient fuel in vehicle tank (
no reserve
), fuel extraction installation cor-
rect, inspect fuel lines for leaks, kinks or clogging.
Remove the heater and carry out troubleshooting in the workshop.
Fig. 502 Overview of functional analysis of heater and components
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