Cruise Control, Idle, or PTO Can Not Be Set

TM 9-2320-312-24-2

Troubleshooting Section

Service Engine Soon Lamp (GM)

a. If the warning lamp does not operate correctly

remove the warning lamp (terminal 29) from

the ECM connector (seventy terminal).

Check the ALDL Connector in order to ensure

that there is not a short circuit between electrical

b. Connect the warning lamp (terminal 29) to the

terminal 4 and electrical terminal 6 or between

ground stud. Turn the ignition key switch to

electrical terminal 5 and electrical terminal 6.

the ON position.

c. Observe the warning lamp.

If the warning lamp comes on, check the

power connection and the ground connection

of the ECM. Refer to Troubleshooting,

"Warning Lamp Circuit - Test" for additional

information.

If the lamp does not come on, check the lamp

in order to ensure that the lamp is not burned

out. Also, check the wiring in order to ensure

that there is not an open circuit.

g00849286

Illustration 17

Cruise Control Set/Resume Switch

GM ALDL cab connector.

(4) BAT Negative

Connect ET to the cab data link connector. Observe

(5) BAT Negative

the status screen for the cruise control set/resume

(6) Diagnostic Enable

switch.

(7) J1587 Data Link Positive

(15) J1587 Data Link Negative

(16) BAT Positive

If the status screen indicates that the switch is on

and the switch is not in the ON position, the switch

is shorted out. Refer to Troubleshooting, "Cruise

i01641517

Control Switch Circuit - Test".

Cruise Control, Idle, or PTO

Short in Vehicle Harness

Can Not Be Set

Check Engine Lamp

SMCS Code: 1408; 1901

Monitor the check engine lamp while the check

Probable Causes

engine lamp (terminal 28) is removed from the ECM

connector (seventy terminal). Also, the technician

The probable root causes are listed in order below:

could monitor the check engine lamp while the ECM

connector (P1) is disconnected.

Customer Specified Parameters (normal

operation)

If the lamp remains on and the pin has been

removed from the ECM, there is a short circuit to

On/Off switch for cruise control and idle control

ground in the vehicle harness.

ET status screen

Warning Lamp

Recommended Actions

Monitor the warning lamp while the warning lamp

(terminal 29) is removed from the ECM connector

Perform the following diagnostic procedures in

(seventy terminal). Also, the technician could

order:

monitor the warning lamp while the ECM connector

(P1) is disconnected.

Customer Specified Parameters

If the lamp remains on and the pin has been

removed from the ECM, there is a short circuit to

When cruise control or idle control is set by using

ground in the vehicle harness.

the cruise control on/off switch, use ET to check

customer specified parameters. Check the following

parameters:

"Low Cruise Control Set Speed Limit"