|
No.
|
TECH
1-DISPLAY
|
Conditions
for Checking
|
Nominal
Value
|
Trouble
Codes
|
Terminal
|
|
|
27
|
IDLE SPEED OFFS.
|
Engine running at idle speed, operating temperature
|
0 rpm
|
-
|
-
|
|
|
|
|
|
|
|
|
|
|
|
|
Note:
The value for idle speed compensation depends on the
programmed value. It can vary by 114 rpm in either the negative or
positive direction.
Carry out corresponding TECH 1 adjustment (section
5.9.1)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Trouble-shooting
|
Nominal Value
|
Cause of
Fault:
(If nominal
value is not attained)
|
|
|
· Ignition OFF
· Disconnect wiring harness plug from DDE
control unit K70
· Ignition ON
· Using multimeter, measure voltage
from: wiring
harness plug for DDE control unit K70 Ter. 47
to: ground
|
lower than 0.1 V
|
· Short circuit to voltage
from: wiring
harness plug for DDE control unit K70 Ter. 47
to: wiring
harness plug for engine speed sensor P51 Ter. 1
· Short circuit to voltage
from: wiring
harness plug for engine speed sensor P51 Ter. 2
to: wiring
harness plug for DDE control unit K70 Ter. 13
· Engine speed sensor P51 defective
|
|
|
· Ignition OFF
· Using multimeter, measure resistance
from: wiring
harness plug for DDE control unit K70 Ter. 47
to: ground
|
greater than 100 kW (¥)
|
· Short circuit to ground
from: wiring
harness plug for DDE control unit K70 Ter. 47
to: wiring
harness plug for engine speed sensor P51 Ter. 1
· Short circuit to ground
from: wiring
harness plug for DDE control unit K70 Ter. 13
to: wiring
harness plug for engine speed sensor P51 Ter. 2
· Engine speed sensor P51 defective
|
|
|
· Using multimeter, measure resistance
from: wiring
harness plug for DDE control unit K70 Ter. 47
to: wiring
harness plug for DDE control unit K70 Ter. 13
|
1250 to 1350 W
|
lower than 1250 W:
· Engine speed sensor P51 defective
· Short circuit in wiring harness
from: wiring
harness plug for control unit K70 Ter. 13
to: wiring
harness plug for control unit K70 Ter. 47
|
|
|
|
|
greater than 1350 W:
· Circuit interruption
from: wiring
harness plug for DDE control unit K70 Ter. 47
to: wiring
harness plug for engine speed sensor P51 Ter. 1
|
|
|
|
|
· Circuit interruption
from: wiring
harness plug for DDE control unit K70 Ter. 13
to: wiring
harness plug for engine speed sensor P51 Ter. 2
· Engine speed sensor P51 defective
|
|
|
|
If nominal values are attained
|
· DDE control unit K70 defective
or
· Engine speed sensor P51 defective
|
|
|
Note:
The tests described above are static checks and not real
function checks. For this reason, it is possible that the measurements are
okay, but that the engine speed sensor still does not function properly. The
cause of this may be mechanical faults or faults in the circuit of the start
of injection sensor. Therefore, before replacing the control unit, first
perform a mechanical function check (see Service Instructions). If there is
no mechanical fault and no fault in the circuit, check the shielding of the
leads before replacing the control unit; i.e. check whether interference is
induced in the wiring harness. Interference can be caused by, among other
things, strong radio transmissions. If this is the case, check the cable
shielding and reinforce or replace it as necessary; it may also be possible
to disrupt the source of interference.
|
|
|
|
|
|
|
|
If, after completion of all checks, the engine speed still
deviates from the nominal value, check the following components:
Coolant
temperature sensor P30 OK?
Pedal
position sensor P67 OK?
Fuel
temperature sensor P68 OK?
Start
of injection sensor P66 OK?
Charge
pressure sensor P65 OK?
Vehicle
speed sensor
(in
rear differential) OK? (see Checking Procedures for
Anti-lock Brake System ABS-2SH)
If all of the above components are okay and the engine
operates correctly, the engine speed regulation deviation can be left
unattended.
Adjustments see section 5.9 "Table 6, Digital Diesel
Electronics DDE 2.1 F6:ADJUSTMENT" test step no. 01 IDLE SPEED
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
