AD83.70-W-6000-27A | AHE test of electrical system coolant circulation pump |
| Scope of test | Measuring instrument/ Test connection | Operation/Requirement | Specified value | Possible cause/Remedy | ||
1.0 | Coolant circulation pump | | Ignition: ON Erase fault code with HHT. Allow heater unit to cool down if necessary, then switch on again. | If fault code re-appears: 1.1 If fault code does not appear: Inspect coolant, replace if necessary. If fault re-occurs or if overheat electrical fuse fails Replace circulation pump. | |||
1.1 | Coolant circulation pump Output voltage on control unit |
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| Z13 A11 | Ignition: OFF Heater unit: ON Carry out measurement directly on 13-pin plug A on control unit (behind timer) and ground. | Value 22.5-29.5 V: 1.2 Value approx. 0 V: 1.5 | |
1.2 | Coolant circulation pump Voltage supply |
12/2 | Heater unit |
12/1 | Ignition: OFF Heater unit: OFF Allow heater unit to cool down. Remove heater unit (under front right fender) and disconnect 12-pin plug connection. Heater unit: ON | Value 22.5-29.5 V: Replace circulation pump Collect draining coolant. Value approx. 0 V: 1.3 | |
1.3 | Coolant circulation pump Voltage supply |
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| FF8 14/1 | Ignition: OFF Heater unit: ON Carry out measurement directly at plug FF8 under electrical compartment and ground. | Value 22.5-29.5 V: 1.4 Value approx. 0 V: Cable to control unit (open-circuit) | |
1.4 | Coolant circulation pump Voltage supply |
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| G 14/1 | Ignition: OFF Heater unit: ON Carry out measurement directly on plug connection G on vehicle blower and ground. | Value approx. 0 V: Cable to plug connection FF8 (open-circuit). Value 22.5-29.5 V: Cable to heater unit (open-circuit). | |
1.5 | Coolant circulation pump Input voltage on control unit |
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| Z13 A13 | Ignition: OFF Heater unit: ON Carry out measurement directly on 13-pin plug A and ground. | Value 22.5-29.5 V: Replace control unit (Z13) on trial. Value approx. 0 V: If heater unit functions only with ignition switched on, check fuse F1 on fuse carrier A1, replace if necessary. If fuse trips again, check circulation pump / supply cable (short-circuit to ground). Check cable / plug connections to fuse and repair. | |