STAR ONLINE PUBLICATION
Case Number: S1508000480
Release Date:

03/27/2020

Symptom/Vehicle Issue: Speed Control Operates Intermittently
Discussion: Cruise/Speed control operation is intermittent. The customer may complain about the
cruise control that does not operate at times. A new switch replacement may not correct the concern.
Check for one of, or more of the following DTC’s: P0579, P0591, P0579-00, P0591-00 and/or P0585.
DS (2011 to 2019), JC (2011 to 2016), JK (2011 to 2016), LC (2011 to 2014, LD, (2011 to 2014), LX
(2011 to 2014), and PF (2013 to 2016) vehicles will display the DTC’s in the SCCM). JK, MK, and RT
(2011 to 2016) vehicles will display the DTC’s in the PCM. DTC’s will be stored always upon initial
investigation. DTC’s will go active only if the cruise does not turn on when the On/OFF button is
pushed and will remain active only during the duration of the button press. If the cruise is turning on
at the time of the investigation the DTC’ will remain stored even if the ON/OFF button is pressed.

Fig 1

For D-Family, JC, JK, LC, LD, LX, MK, and RT vehicles:
1. Using Wi-tech measure the S/C input voltages for S/C voltage inputs 1 and 2 signals while
pushing and holding the on button (see Fig 1 and Fig 2, Fig 3 for voltage monitoring).

This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online does
not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear to be
similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the appropriate
course of action.

Contact STAR Center, or your Technical Assistance Center Via TechCONNECT or eCONTACT ticket if no
solution is found
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Fig 2
This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online does
not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear to be
similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the appropriate
course of action.

Contact STAR Center, or your Technical Assistance Center Via TechCONNECT or eCONTACT ticket if no
solution is found
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If the cruise control icon does not display in the cluster, one or both of the signal voltages may
be over the Vmax value; 0.353 (Signal 1) or 0.980 (Signal 2); see Fig 3. Once one of these
voltages exceeds the Vmax value the system will disable the cruise control and prevent it from
turning on since a voltage is out of the parameters that the system recognizes in order to
determine a legitimate button press. The voltage that is exceeding the value, i.e., Signal 1 or
Signal 2, will determine the DTC that is set. If Signal 1 voltage is over Vmax, P0579 will be
set. If Signal 2 voltage is over Vmax, P0591 will be set. Again the DTC’s only remain active
during the time the on button is being pressed. Once the button is released the voltages will
increase to approximately 4.54 volts. Since this value is within the range of voltages when no
button is being pressed, the system is seeing a correct voltage and therefore does not show an
active DTC (see Fig 3).
Signal 1 Cruise Control voltage Values
Function
Vmin
Vnom
Vmax
Circuit Low 0.000
-0.216
ON/OFF
0.235
0.300
0.353
Cancel
0.784
0.890
0.980
Distance
1.373
1.500
1.627
Mode
1.941
2.100
2.235
SET2.549
2.700
2.843
RES+
3.137
3.300
3.451
None
4.373
4.540
4.686
Circuit High 4.706
5.000

Signal 2 Cruise Control voltage Values
Function
Vmin
Vnom
Vmax
Circuit Low 0.000
-0.784
ON/OFF
0.804
0.900
0.980
Cancel
1.353
1.500
1.608
Distance
1.941
2.100
2.235
Mode
2.529
2.700
2.843
SET3.137
3.300
3.451
RES+
3.725
3.900
4.059
None
4.373
4.540
4.686
Circuit High 4.706
5.000

Fig 3
2. If, one or more of these voltages is over Vmax, follow the procedures in DealerConnect for
removing the airbag/horn switch assembly in the steering wheel. Once the airbag/horn switch
assembly has been removed, disconnect the 6 pin steering wheel harness connector to the
SCCM/clock spring assembly and reconnect it. Re-measure the S/C Signal voltages while
pushing and holding the ON/OFF button. If the voltages drop to the nominal values,
0.290/0.300 (Signal 1) and 0.890/0.90 (Signal 2) the intermittent cruise problem has been
corrected. Any contamination/oxidation that was present on the connector terminals that was
causing an increase in resistance, which resulted in the increased voltage or voltages, was
brushed aside or removed during the re-installation of the connector. Re-install the

This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online does
not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear to be
similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the appropriate
course of action.

Contact STAR Center, or your Technical Assistance Center Via TechCONNECT or eCONTACT ticket if no
solution is found
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airbag/horn switch assembly and return the vehicle to the customer. No other repairs are
necessary.
3. If, the cruise control ready icon does display in the cluster, and the signal input voltages are
not at Vnom, i.e., 0.290/0.300 (Signal 1), or 0.890/0.900 (Signal 2), but are slightly higher, ie.,
0.320 to 0.350 (Signal 1) or 0.920 to 0.979 (Signal 2), follow the procedures in DealerConnect
for removing the airbag/horn switch assembly from the steering wheel. Once the airbag/horn
switch assembly has been removed, disconnect the 6-pin steering wheel harness connector
(Uplink Connector) to the SCCM/clock spring assembly and reconnect it. Re-measure the S/C
Signal voltages while pushing and holding the on button. If the voltages drop to the nominal
values, 0.290/0.300 volts the intermittent cruise problem has been corrected. Note: If the
voltages do not drop to the nominal values, perform the same disconnect and reconnect
procedure to the 6-pin connector (Downlink Connector) on the opposite side of the SCCM.
4. If the cruise control Signal voltages are at Vnom, graph the speed control input voltages on
the same screen while pushing and releasing the on button. If the switch is performing
correctly, the input voltages will be almost a mirror image of each other as shown below in Fig
4.

Fig 4
This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online does
not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear to be
similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the appropriate
course of action.

Contact STAR Center, or your Technical Assistance Center Via TechCONNECT or eCONTACT ticket if no
solution is found
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If the switch is not performing correctly, the switch voltages may not be a mirror image of each
other as shown below in Fig 5.

Signal 1 voltage should have
dropped here. Contact 1 did
not close. Replace switch.

Fig. 5

Signal 1 switch contact did not close when signal 2 closed. This can cause a P0579 and the
cruise will not turn on. In this case, the S/C switch should be replaced.

Verification:
Test the operation to complete.

This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online does
not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear to be
similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the appropriate
course of action.

Contact STAR Center, or your Technical Assistance Center Via TechCONNECT or eCONTACT ticket if no
solution is found
FCA US LLC

Version 4.2 02/06/2017