Fault Code Guide

PTO and Fire Pump Controls
Electrical Troubleshooting
Use Table 1 or Table 2 to begin troubleshooting. For
power takeoff (PTO) function electrical diagnosis, see
Table 1. For fire pump controls function diagnosis,
see Table 2.
Additional tables included in this subject are:
• Table 3: PTO and Fire Pump Control Switch
and Interlocks Test
• Table 4: PTO Interlocks by Reference Param-
eter
• Table 5: Fire Pump Control Interlocks by Ref-
erence Parameter
• Table 6: PTO and Fire Pump Control J1587
Fault Codes
• Table 7: PTO and Fire Pump Control J1939
Fault Codes
PTO Function Electrical Diagnosis
Test
No.
Test Procedure Test Result Action
1 In ServiceLink
®
, use the Chassis Module (CHM) Configuration
screen to determine which CHM solenoid output number
controls the solenoid for the PTO.
Then open the "AMU Solenoids Circuits" or "AAVA Solenoids
Circuits" in the appropriate Datalink Monitor template.
Make sure the vehicle has full air pressure. Turn the ignition
on.
Attempt to engage the PTO using the smart switch in the
dash while observing the status of the solenoid output under
the "Outputs from BHM" heading for the solenoid number
determined above. See Fig. 1 and Fig. 3.
Does the output status turn on at all? It may turn on, then
drop out.
Yes
Go to test no. 2.
No
Perform the PTO and Fire Pump
Control Switch and Interlocks Test in
Table 3.
2 Using the appropriate solenoids Datalink Monitor template,
enter Test Mode.
Attempt to turn the PTO solenoid on using the ON button on
the template.
NOTE: When done, exit Test Mode.
When you attempt to turn on the PTO solenoid, can you hear
it click?
Yes
Go to test no. 3.
No
Go to test no. 5.
3 Make sure the vehicle has full air pressure. Turn the ignition
on.
Using the appropriate solenoids Datalink Monitor template,
attempt to engage the PTO using the smart switch in the dash
while observing the status of the pressure switch under the
"Inputs to BHM" heading for the solenoid number that controls
the PTO. See Fig. 2 and Fig. 3.
Does the status of the pressure switch say AIR ON at all,
even if it comes on, then goes off?
Yes Go to test no. 4.
No
Check PTO solenoid pressure switch
feedback circuit.
Check the solenoid pressure switch.
See Section 42.19.
Check if air line is connected to
solenoid.
If the above items are OK, replace
CHM.
PTO and Pump Electrical Controls 54.38
Troubleshooting
Business Class M2 Workshop Manual, Supplement 22, September 2012 300/1