Fast Idle Enable Circuit

273

TM 9-2320-312-24-2

Troubleshooting Section

F. Alternately remove the jumper wire and then

D. Insert the jumper wire into terminal 7 of the

insert the jumper wire at the terminals on the

breakout T. Connect the other end of the jumper

diagnostic module. At the same time, watch the

wire to terminal 18 in the breakout T. Terminal 18

status screen on Cat ET.

is input sensor common 1.

E. Connect Caterpillar Electronic Technician (Cat

Expected Result:

ET) to the cab data link connector.

The input status changes to "ON" with the jumper

wire in place. The input status changes to "OFF"

F. Turn the ignition key switch to the ON position.

when the jumper wire is removed.

G. Alternately remove the jumper wire and then

insert the jumper wire from terminal 18. At the

Results:

same time, monitor the status screen on Cat ET.

OK The vehicle wiring is OK.

Expected Result:

Repair: Refer to System Operation, Testing and

The input status changes to "ON" with the jumper

Adjusting, RENR1271 and Special Instruction,

wire in place. The input status changes to "OFF"

REHS1314, "Johnson Mathey CRTdm Interface

when the jumper wire is removed.

Software Guide" for troubleshooting the diagnostic

module.

Results:

STOP.

OK The ECM is functioning properly at this

Not OK The problem is in the vehicle wiring

time. Proceed to Test Step 3.

between the ECM and the diagnostic module.

Not OK The ECM is not functioning properly.

Repair: Inspect the vehicle wiring and then repair

the vehicle wiring. Otherwise, send the vehicle to

Repair: Perform the following repair:

the OEM dealer for repair. Verify that the original

condition is resolved.

1. Temporarily connect a test ECM.

2. Remove all jumpers and replace all connectors.

STOP.

3. Recheck the system for active diagnostic

i01479400

codes.

Fast Idle Enable Circuit - Test

4. Repeat the Test Step.

SMCS Code: 1900-081

5. If the problem is resolved with the test ECM,

reconnect the suspect ECM.

System Operation Description:

6. If the problem returns with the suspect ECM,

Use this procedure under the following situation:

replace the ECM.

Use this procedure to determine if the fast idle

7. Verify that the repair eliminates the problem.

switch is operating correctly.

STOP.

The following background information is related

to this procedure:

Test Step 3. Insert a Jumper Wire at the

Diagnostic Module

A fast idle switch (momentary switch) and a fast

idle lamp can be installed. The operator can use

A. Turn the ignition key switch to the OFF position.

the fast idle switch in either of the following ways:

B. Reconnect the ECM vehicle harness connector

Press and release the fast idle switch in order to

J1/P1.

use the engine speed that is programmed into

the "Fast Idle RPM #1" parameter.

C. Fabricate a jumper wire 100 mm (4 inch) long.

Crimp a Deutsch pin to both ends of the wire.

Use the accelerator pedal to accelerate the

engine to the desired engine speed. Press and

D. Insert the jumper wire between the two terminals

release the fast idle switch in order to maintain

at the diagnostic module.

the engine speed at the desired engine speed.

E. Turn the ignition key switch to the ON position.