AD83.70-W-6000-22C | AHE test of electrical system metering pump, temperature circuit breaker, control module open circuit |
| Scope of test | Measuring instrument/ Test connection | Operation/Requirement | Specified value | Possible cause/Remedy | ||
1.0 | Fuel metering pump (M16) Fuse F1-A1 | - | Ignition: ON Heater unit: ON Check fuse, replace if necessary. Switch on heater unit again. | Fault code does not appear, heater unit running: If fuse trips again later, inspect cabling from heater unit and timer to metering pump (M16) (sporadic short-circuit). If fault code re-appears (fuse in order): 1.1 | |||
1.1 | Fuel metering pump (M16) Overheat electrical fuse and cabling |
14/2 () | G |
14/7 | Ignition: ON Heater unit: OFF Open flap on air recirculation box (above vehicle blower). Carry out measurement directly to 14-pin plug connection G in air recirculation box. | Value 22.5-29.5 V: 1.3 Value < 1 V: 1.2 | |
1.2 | Fuel metering pump (M16) Overheat electrical fuse |
14/2 () | G |
14/11 | Ignition: ON Heater unit: OFF Carry out measurement directly to 14-pin plug connection G in air recirculation box. | Value 22.5-29.5 V: Replace overheat electrical fuse on trial. Plug connection under electrical compartment and cabling (open-circuit). defective temperature-controlled cutout before operation of heater unit 1.4 Value approx. 0 V: 1.3 | |
1.3 | Fuel metering pump (M16) Internal resistance |
a | M16 |
b | Ignition: OFF Heater unit: OFF Carry out measurement at both fuel metering pump connections in front right vehicle longitudinal frame | 35–45 Ω | Value in order: 1.6 Value > 30 kΩ: Replace metering pump (M16) on trial. |
1.4 | Fuel metering pump (M16) Circulation pump voltage supply |
14/2 | G |
14/1 | Ignition: ON Heater unit: OFF Carry out measurement directly at 14-pin plug connection G in air recirculation box. | Value 22.5-29.5 V: 1.5 Value < 1 V: 1.6 | |
1.5 | Fuel metering pump (M16) Internal resistance Circulation pump |
12/2 | Heater unit |
12/1 | Ignition: OFF Heater unit: OFF Allow engine and heater unit to cool down. Remove cover in right wheel housing and remove heater unit if necessary. Disconnect 12-pin plug on heater unit. | 90–130 Ω (at 20 °C) | Value in order: By actuating (+ 24V), check whether heater circulation pump is running, replace on trial if necessary. Check cabling / plug connection FF8 under electrical compartment to heater unit. On vehicles where GGVS applies, erase fault code if, from time to time heating is turned off via EMERGENCY OFF switch (without run-on). Value >30 kΩ: Replace circulation pump on heater unit / interference suppression set on trial. |
1.6 | Fuel metering pump (M16) Control unit (Z13) |
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| Z13 A11 | Ignition: ON Heater unit: OFF Connect measuring instrument on 13-pin plug A from control unit (behind radio console) and ground. Heater unit: ON | Value 22.5-29.5 V: Check cabling / plug connections to heater unit for open-circuit / loose contact. Value < 1 V: Replace control unit (Z13) on trial. | |