Fault Diagnosis; Activating Fault Diagnosis - Volvo DH10A 245 Service Manual

Pin Signals to/from control unit 9058
32 Speed signal from relay box 3060
2/1 Voltage feed
18/12/30/5 Signals from "cruise control" (1125). In series
between pin 5 and the cruise control stalk there
is also a pressure breaker (2008) that breaks the
current during braking.
9 C3-signal from speedometer/tachograph.
16 Voltage from activated exhaust brake (breaks
cruise control function) and accelerator pedal
function.
7 PWM (Pulse Wide Modulated) voltage signal to
automatic transmission and ASR-system (Anti-
Slip Regulation) passes on information on the
throttle position.
25 Signal from ASR-system concerning dethrot-
tling with skidding.
15 Input and output for diagnostic lamp.
21/3 Outsignal to adjuster device on governor (6064)
for regulating throttle.
6/29/10 Control rod position from sensor in governor
(6064).
31 Speed from sensor in governor (6064).
26 Intercooler temp. from sensor (7067) in inlet
pipe.
23 Coolant temp. from sensor (756B) in thermostat
housing cover on B10B and in discharge pipe af-
ter engine (to retarder) pn B12.

Fault diagnosis

The EDC-system monitors sensors, functions and the
governor adjuster device. With fault, the diagnostic
lamp lights, either continuously or with blinks. Fault
coding is based on diagnostic lamp blinks. To get this,
depress the diagnostic switch (button). Several faults
can be stored simultaneously in the control unit mem-
ory.

Activating fault diagnosis

Turn the start key to the drive position, depress the
diagnostic switch. Release it after a few seconds and
count the number of blinks. Note the number. It corre-
sponds to a specific fault code. If two or more faults are
stored, the lamp will show them after each other. The
diagnostic switch must be depressed to start the next
blink sequence. The lamp shows all the blink codes
when it returns to the first one.
How to erase stored fault codes:
Turn the start key to the "0" position. Keep the dia-
gnostic switch depressed and at the same time turn the
start key (feed selector switch) to the drive position. Do
not release the diagnostic switch. Keep it depressed for
150
35 Sensor earth.
17/13 Accelerator pedal position from position sensor,
accelerator pedal (7065). In the EDC-system,
the kick-down breaker for automatic transmis-
sion is housed in the position sensor.
33/34 Intercooler pressure sensor (7066). A 5 V refer-
ence voltage (outsignal) comes in from 33 and a
voltage of 1.3–2.5V is sent to 34, depending on
the charge pressure.
11 Voltage from activated brake lights (breaks
cruise control function).
28 Control rod position signal from control unit.
14 Not used.
20/19 Earth connection.
4 Doubled engine shut-off (apart from switching
off power to adjuster device on governor) is ef-
fected by a "+" to the solenoid valve (603)
which, via a compressed-air cylinder (emergen-
cy stop) activates the injection pump stop lever.
Breaking "+" to the solenoid valve 603 opens
the valve.
27 Position breaker (2007) on the clutch pedal
earths when the clutch pedal is released. (Ap-
plies only to manual gearbox – for automatic
transmission, see pin 6 relay box.)
about 3 seconds. Release the diagnostic switch. This
should erase all stored fault codes.
With failure in the normal voltage feed to the control
unit, the indicator lamp EDC+ for voltage feed comes
on and gives a steady light. If there is nothing wrong
with the voltage feed, the control unit is doubly protect-
ed against voltage failure and the lamp goes out.
Should the lamp light when driving, the bus can be
driven as usual but. to avoid risk of total voltage break-
down, which would mean that the engine would stop, it
is recommended that the fault be put right without de-
lay.