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