5031481 JOHNSON *SWITCH, EMERGENCY

Table 1
Diagnostic Trouble Codes    
CDL Code    Code Description    Comments    
338-5     Engine Pre-Lube Pump Relay : Current Below Normal     The code is logged.
The engine Electronic Control Module (ECM) detects current that is out of range.
The ECM can only detect this condition when the prelube pump relay is not energized.    
338-6     Engine Pre-Lube Pump Relay : Current Above Normal     The code is logged.
The engine ECM detects current that is out of range.
The ECM can only detect this condition when the prelube pump relay is not energized.    The ECM can automatically lubricate the engine before cranking. The life of certain engine parts is increased by lubricating the parts before the starting motor is engaged.The prelubrication system is activated when the keyswitch is turned to the START position. The system prevents the starting motor from engaging while the pump builds engine oil pressure. After a short period, the starting motor is allowed to engage. The keyswitch must be left in the START position for the duration of the prelube cycle. Proper lubrication of the engine will then be assured before start-up.A test on Caterpillar Electronic Technician (ET) allows the technician to activate the prelube system. The test is functional when the engine speed is 0 rpm. The test is accessed by selecting the following menus on Cat ET:
"Diagnostics"
"Diagnostic Tests"
"Override Parameters"
Illustration 1 g02169293
Typical schematic
Illustration 2 g01149844
Terminal locations of the prelube relay
Table 2
Troubleshooting Test Steps     Values     Results    
1. Check the Power Supply to the Prelubrication Relay
A. Measure the voltage between terminal 30 (+Battery) of the prelubrication relay and chassis ground.
   
24.0 8.0 VDC
   
Results: The supply voltage is 24.0 8.0 VDC. - Proceed to Test Step 2.
Results: The supply voltage is not 24.0 8.0 VDC. - There is a problem in the wiring between the prelubrication relay and the +Battery.
Repair: Repair the circuit. Verify that the repair eliminates the problem.
STOP
   
2. Check the Output Voltage of the Prelubrication Relay
A. Proceed to the "Diagnostic Override Screen" in Cat® Electronic Technician (ET).
B. Activate the prelubrication system.
C. Measure the voltage between terminal 85 (+Battery) of the prelubrication relay and chassis ground.
   
24.0 8.0 VDC
   
Results: The output voltage is 24.0 8.0 VDC. - Proceed to Test Step 8.
Results: The output voltage is not 24.0 8.0 VDC. - Proceed to Test Step 3.
   
3. Check the Resistance of the Prelubrication Relay
A. Turn the keyswitch to the OFF position.
B. Measure the resistance across terminal 86 (signal input) and terminal 85 (ground terminal) of the prelubrication relay.
   
Resistance between 250 Ohms and 500 Ohms
   
Results: The resistance is between 250 Ohms and 500 Ohms. - Proceed to Test Step 4.
Results: The resistance is not between 250 Ohms and 500 Ohms. - The relay is faulty.
Repair: Replace the relay. Verify that the repair eliminates the problem.
STOP
   
4. Check the Signal Voltage to the Prelubrication Relay
A. Turn the keyswitch to the ON position. Do not start the engine.
B. Proceed to the "Diagnostic Override Screen" in Cat ET.
C. Activate the prelubrication system.
D. Measure the voltage between terminal 86 (signal voltage) of the prelubrication relay and chassis ground.
   
24.0 8.0 VDC
   
Results: The signal voltage is 24.0 8.0 VDC. - Proceed to Test Step 8.
Results: The signal voltage is not 24.0 8.0 VDC. - Proceed to Test Step 5.
   
5. Check the Ground Circuit for the Prelubrication Relay
A. Turn the keyswitch to the OFF position.
B. Measure the resistance between terminal 85 of the prelubrication relay and chassis ground.
   
Open Circuit
   
Results: The resistance does not indicate an open circuit. - Proceed to Test Step 6.
Results: The resistance indicates an open circuit. - The ground for the relay for the prelubrication pump is faulty.
Repair: Repair the circuit. Verify that the repair eliminates the problem.
STOP
   
Illustration 3 g02169233
P1 ECM connector (P1-13) Prelube relay
Table 3
Troubleshooting Test Steps     Values     Results    
6. Check the Harness to the ECM
A. Turn the keyswitch to the OFF position.
B. Disconnect the J1/P1 ECM connector.
C. Remove the wire from terminal P1-13 (prelubrication relay signal).
D. Reconnect the J1/P1 ECM connector.
E. Disconnect the connector for the prelubrication relay.
F. Use a suitable piece of wire to short terminal 86 (signal voltage ) and terminal 85 (return) on the connector for the prelubrication relay.
G. Measure the resistance between the end of the wire from terminal P1-13 (prelubrication relay signal) and chassis ground.
   
Open Circuit
   
Results: The resistance does not indicate an open circuit. - Proceed to Test Step 7.
Results: There is an open circuit in the wiring harness between the prelubrication relay and the ECM.
Repair: Repair the circuit. Verify that the repair eliminates the problem.
STOP
   
7. Check the ECM
A. Turn the keyswitch to the OFF position.
B. Disconnect the J1/P1 ECM connector.
C. Install a jumper wire into terminal P1-13 (prelubrication relay signal).
D. Reconnect the J1/P1 ECM connector.
E. Return the wiring at the prelubrication relay to the original configuration.
F. Turn the keyswitch to the ON position. Do not start the engine.
G. Proceed to the "Diagnostic Override Screen" in Cat ET.
H. Activate the prelubrication system.
I. Measure the voltage between the jumper wire from terminal P1-13 (prelubrication relay signal) and chassis ground.
J. Turn the keyswitch to the OFF position.
K. Restore the wiring to the original configuration.
   
24.0 8.0 VDC
   
Results: The supply voltage is 24.0 8.0 VDC. - Proceed to Test Step 8.
Results: The supply voltage is not 24.0 8.0 VDC. - There is a problem with the ECM.