Volvo Engine Brake VE D12, D12A, D12B. Manual — part 8
Group 25
Troubleshooting
2531-06-02-03
Exhaust Brake, Mechanical
Checking
Before working on a vehicle, set the parking brakes,
place the transmission in neutral, and block the
wheels. Failure to do so can result in unexpected ve-
hicle movement and can cause serious personal
injury or death.
WARNING
HOT ENGINE! Keep yourself and your test equipment
clear of all moving or hot engine parts. A hot engine
can cause serious burns or can permanently damage
test equipment.
WARNING
Always wear appropriate eye protection to prevent the
risk of eye injury due to contact with engine debris or
fluids.
Note: Before carrying out the following procedure, read
the troubleshooting general information in “Engine Brake,
Fault Tracing” page 15.
Special tools: 9996465, 9998333
Test 1
1
W2002234
1 EPG solenoid (cold mode)
2 Exhaust brake solenoid
Verify proper wiring to solenoids. Wire
628 to the exhaust brake solenoid and
wire 636k to the exhaust pressure
governor (EPG) solenoid.
2
Verify correct air regulator valve is
used with the proper system. The ex-
haust brake requires the 7.5 bar
regulator, while the EPG utilizes a 2.3
bar regulator.
3
W2002198
VN solenoid location — other vehicles have
solenoids located on bulkhead
Connect the J–42472 2-pin breakout
harness to the exhaust brake solenoid
valve, using 2 jumper wires with
“alligator” type ends, supply the sole-
noid with an alternate ground and B+
and listen to hear if the exhaust pres-
sure governor shutter moves.
Note: Make sure that pin 1 of the J–
42472 is connected to B+ and pin 2 is
connected to B-.
4
T2007700
If the exhaust pressure governor shut-
ter moves, carry out test 3.
32
Group 25
Troubleshooting
5
T2007701
If the exhaust pressure governor shut-
ter does not move, remove the air
hose from the exhaust pressure gover-
nor and activate the exhaust brake
solenoid valve again.
6
If no air comes out of the hose, carry
out Test 2.
If air comes out of the hose, carry out
Test 3.
Test 2
1
Check that the air hoses are not
twisted or blocked.
Replace damaged hoses.
2
T2007953
Remove the air hose from the quick
release valve and activate the exhaust
brake solenoid valve.
If air comes from the hose, the quick
release valve is faulty and should be
replaced.
3
If no air comes out of the hose, check
that air reaches the exhaust brake so-
lenoid valve.
If air reaches the exhaust brake sole-
noid valve, the valve is faulty and
should be replaced.
4
If no air reaches the exhaust brake so-
lenoid valve, check that air reaches the
regulator valve for the exhaust brake
solenoid. If no air reaches the air reg-
ulator valve, check or replace the air
supply hose. If air reaches the air reg-
ulator valve, then the air regulator
valve is faulty and should be replaced.
33
Group 25
Troubleshooting
Test 3
1
T2007707
Connect the pressure gauge to the ex-
haust pressure governor hose and
activate the exhaust brake solenoid
valve.
Note: The pressure in the hose should
be 7.5 ± 0.3 bars (109 ± 4.4 psi).
999 6465
999 8333
2
If the pressure is too high or too low,
carry out Test 4.
If the pressure is within the tolerances,
carry out Test 5.
Test 4
1
Check that the hoses are not twisted
or blocked.
Replace damaged hoses.
999 6465
999 8333
2
W2002211
1 EPG solenoid (cold mode)
2 Exhaust brake solenoid
Solenoids are located on the bulkhead; VN vehicles
have solenoids mounted on the engine
Remove the hose from the exhaust
brake solenoid valve and measure the
output pressure. The pressure should
be 7.5 ± 0.3 bars (109 ± 4.4 psi).
Never disconnect an air system component unless all
system pressure has been depleted. Failure to deplete
system pressure before disconnecting hoses or com-
ponents may result in their violent separation and can
cause serious bodily injury.
3
If the pressure is within the tolerances,
the quick release valve is faulty and
should be replaced.
34
Group 25
Troubleshooting
4
W2002212
If the pressure is too high, go to step 4.
If the pressure is too low, go to step 5.
Note: Trucks with a higher system
pressure than 7.5 bar (109 psi) are
equipped with an adjustable reduction
valve to reduce the pressure to the ex-
haust pressure governor.
5
Adjust the valve setting to specified
pressure. If pressure will not respond
to adjustment, replace regulator. After
adjustment, the knob on the valve
should be sealed or made tamper
proof.
6
Check the outlet pressure of the regu-
lator going to the exhaust brake
solenoid.
Intended value: 752 ± 30 kPa (109 ±
4.4 psi)
7
Pressure OK:
•
Restriction in line from regulator
valve to exhaust brake solenoid.
(VN series)
•
Faulty solenoid.
8
Pressure not OK:
•
Regulator valve out of adjustment
or faulty.
•
Insufficient supply pressure.
Test 5
1
Remove the exhaust pipe from the
shutter housing.
2
W2002189
Measure the opening between the
shutter disk and shutter housing (A),
to check that the EPG shutter has not
jammed in the closed or half-closed
position.
The value (measurement A) should
be 30 ± 2 mm (1.18 ± .08 in).
3
If the value is correct, replace or over-
haul the EPG in accordance with the
procedures found in:
Service
Manual
V776–250–600SM
Intake and Exhaust
Systems, VE D12
4
Activate the exhaust brake solenoid
valve.
35
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