Volvo Symptom D12D US02 Service Manual page 78

Group 20
•
"Step 3: VCADS Pro Tests" page 83
•
"Step 4: Component and Function Checks" page 85
Engine Speed Surges in Power Take-off or Cruise Control
The following checks should be carried out in order until
the fault is found. These checks also can help eliminate
components with no faults or malfunctions. The number of
tests and the order depends on the following: results from
Related Symptoms
In some cases, other symptoms may be noticed. In these
cases, instructions in other Service information may be
helpful for fault tracing:
•
Group 20: Low Power Output
•
Group 20: Starting and Stopping Problems
•
"Step 1: Fault Code Readings" page 86
•
"Step 2: Visual Inspection (System Checks)" page 87
Step 1: Fault Code Readings
Active and inactive registered fault codes can point to
faults but also be a fault finding aid for the symptom.
Action:
Check for active or inactive fault codes related to symptoms.
Check inactive codes with high number of occurrences.
"Step 2: Visual Inspection (System Checks)" page 75
74
C2002639
D
"Uneven Operation, Fault Tracing" page 71
tests and fault codes, vehicle conditions, vehicle service
and repair history, other symptoms, and information from
the driver.
•
"Step 3: VCADS Pro Tests" page 87
•
"Step 4: Component and Function Checks" page 88
"Uneven Operation, Fault Tracing" page 71
Freeze frames of information for specific fault codes may
also be helpful for finding causes for the symptom.
Fault tracing using relevant service information
should always be carried out for relevant fault codes.
Components/functions of special interest:
•
MID 128, Engine ECU
PID 94 Fuel supply pressure
PPID 122 VCB compression brake status
PPID 124 Exhaust pressure governor, EPG 1
SID 1–6 Unit injectors
SID 21 Engine position, cam
SID 22 Engine speed, flywheel
SID 146 EGR valve 1
SID 266 EGR valve 2 (D12D)
Refer to:
Instrument cluster or VCADS Pro
VCADS Pro: "Fault Codes, Test Mode"
"Engine Runs Unevenly at Idle Speed" page 73