Wait To Start Lamp Circuit

417

TM 9-2320-312-24-2

Troubleshooting Section

F. Compare the Vehicle speed reading on the ET

Refer to Illustration 188.

status screen to the vehicle speedometer and

the actual vehicle speed.

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

D. Connect ET to the cab data link connector.

Expected Result:

The "Vehicle Speed" on the ET status screen is

E. Access the "55 mph VSP/Speedometer Test" by

within 8 km/h (5 mph) of the speedometer and the

Accessing the following display screens in order:

actual vehicle speed readings.

"Diagnostics"

Results:

"Diagnostic Tests"

Yes The ECM is receiving J1939 data from the

"Special Test menu"

transmission ECM. Send the vehicle to the OEM

dealer for repair of the wiring for the speedometer

or for the repair of the transmission vehicle speed

F. Activate the test and observe the vehicle speed

sensor. STOP.

on the vehicle speed status screen.

No Perform the following repair:

Expected Result:

ET indicates a constant vehicle speed between

Repair: Connect a test ECM. Program all of the

80 to 96 km/h (50 to 60 mph) when the jumper wires

parameters that are related to vehicle speed to

from the speedometer circuit are connected.

the same setting as the original ECM. Repeat

the previous test step. If the test ECM functions

properly and the original ECM does not function

Results:

properly, replace the ECM. If the test ECM does

not correct the problem, send the vehicle to the

OEM dealer for repair of one of the following

components:

Repair: Perform the following repair:

speedometer

Reconnect the suspect ECM. If the problem

returns with the suspect ECM, replace the ECM.

wiring

STOP.

Transmission ECU

Not OK Recheck the connectors. Continue

transmission speed sensor

troubleshooting until original condition is resolved.

STOP.

wiring for the J1939 data link

Test Step 9. Verify Correct Programming

for the "J1939 Vehicle Speed Calibration"

STOP.

Parameter

i01611459

A. Connect ET to the cab data link connector.

Wait To Start Lamp Circuit -

B. Access the list of "Configuration Parameters"

Test

on the service tool and verify that the "Vehicle

Speed Input" parameter is programmed to the

SMCS Code: 7431-081

"J1939 Trans" option.

System Operation Description:

C. Verify that the "Powertrain Datalink" parameter is

programmed to "J1939".

Use this procedure under the following situation:

D. Verify that the correct value is used for the

Use the following information in order to determine

"Vehicle Speed Cal (J1939-Trans)" parameter.

if the Wait to Start Lamp is operating incorrectly.

Refer to Troubleshooting, "Vehicle Speed Circuit

- Calibrate" for details.

Terminal 31 (Output 9)

E. Verify that the J1939 data link is connected to

the ECM and that the data link is functioning

properly. Refer to Troubleshooting, "Powertrain

Datalink Circuit - Test".