SHIELD AS-TURBO RH 1W9724 - Caterpillar

Illustration 1 g03710730
(1) Common
(2) Relay coil
(3) N.C. contact
(4) N.O. contact
(5) Relay coil
Illustration 2 g03710732
(1) Common
(2) Relay coil
(3) N.C. contact
(4) N.O. contact
(5) Relay coil
Table 1
Switch Position Resistance
OFF Pins 1 and 2: less than 5.0 Ohms
RUN Pins 1 and 2: less than 5.0 Ohms
START (Momentary) Pins 1, 3 and 4: less than 5.0 Ohms
Table 2
Engine Functions Do Not Respond to Operator Console
Troubleshooting Test Steps Values Results
Test Step 1. Visually Inspect the Engine Start Relay
A. Inspect the Engine Start Relay.
Check the housing for cracks or other damage.
Check the relay for damaged, burnt, or bent terminals.
The relay shows no signs of damage. OK – The relay shows no signs of damage.
Proceed to Test Step 2.
Not OK – The relay appears damaged.
Repair: Replace the relay and check machine operation.
STOP.
Test Step 2. Test the Relay in the Deenergized State
A. Remove the electrical power from the ECM.
B. Disconnect the relay from the circuit.
C. Verify the operation of the relay in the deenergized state.
D. Measure continuity across the following terminals of the relay:
Terminal 1 to terminal 3
Terminal 5 to terminal 2
Terminal 1 to terminal 4
Refer to Illustrations 1 and 2.
The following results were obtained:
Terminal 1 to terminal 3 indicated a short circuit.
Terminal 5 to terminal 2 indicated some measured resistance.
Terminal 1 to terminal 4 indicated an open circuit.
Refer to Illustrations 1 and 2. OK – Each measurement was correct.
Proceed to Test Step 3.
Not OK – A measurement was incorrect.
Repair: Replace the relay and retest the circuit.
STOP.
Test Step 3. Test the Relay in the Energized State.
A. Apply the appropriate voltage across the coil of the relay.
Refer to Illustrations 1 and 2.
The following results were obtained:
Terminal 1 to terminal 3 indicated an open circuit.
Terminal 1 to terminal 4 indicated a short circuit.
Refer to Illustrations 1 and 2. OK – Each measurement was correct.
Proceed to Test Step 4.
Not OK – A measurement was incorrect.
Repair: Replace the relay and retest the circuit.
STOP.
Test Step 4. Check the Engine Keyswitch
A. Remove the connector from the switch.
B. measure the resistance between switch contacts, with the switch in the ON position and then in the OFF position.
Record the results.
The resistance measurements meet the specifications in Table 1 OK – The resistance measurements meet the specifications in Table 1.
Proceed to Test Step 5.
Not OK – The resistance measurements do not meet the specifications in Table 1.
Repair: Replace the Engine Keyswitch and check the machine operation.
STOP.
Test Step 5. The Harness Between the Engine Keyswitch and the ECM has Failed.
Using the system electrical schematic, check the harness and connectors between the Engine Keyswitch and the ECM for:
Wire to wire shorts
Shorts to ground
Shorts to power
Open circuits
There are no defects in the harness or connectors between the Engine Keyswitch and the ECM. OK – There are no defects in the harness or connectors between the Engine Keyswitch and the ECM.
Proceed to Test Step 6.
Not OK – Defects are found in the harness and or connectors.
Repair: Repair or replace the harness and or connectors and check the machine operation.
STOP.
Test Step 6. Toggle the Throttle to High Idle A.
With the engine running at