Cherokee 2WD L6-4.0L VIN S (1998)
Idle Speed/Throttle Actuator - Electronic: Testing and Inspection
Extended Idle Switch
OPTIONAL POLICE PACKAGE ONLY
The extended idle switch is used to raise engine idle speed to approximately 1000 rpm when the shifter is in either Park or Neutral position. A
rocker-type switch (extended idle switch) is mounted to instrument panel. This switch is available only with 4.OL engine when supplied with optional
police package.
The extended idle switch will control a ground circuit going to the poweftrain control module (PCM). When a ground signal (through the switch) has
been received at pin/cavity A-12 (circuit K78) of the PCM, engine idle speed will increase.
1. Bring engine to normal operating temperature and turn extended idle switch to ON position. Engine idle speed should now increase to
approximately 1000 rpm when shifter is in either Park or Neutral position.
2. If idle speed does not increase, uriplug 4-way electrical connector from switch.
3. Check circuit Z1L for ground. Ground should be present at all times. If not, repair open circuit to ground.
4. If ground is present at Z1L, check continuity of switch between circuits ZiL and K78. If continuity is not present, replace switch. If switch is OK
proceed to next step.
5. With 4-way electrical connector still unplugged from switch, apply a good ground to circuit K78. Engine idle speed should increase. If not,
proceed to next step.
6. Ground pin/cavity A-12 directly at PCM using a small paper clip. Be careful not to damage wiring with paper clip. If engine idle speed increases,
it can be assumed that PCM is functioning correctly Repair open circuit in circuit K78. If engine idle speed will not increase after applying a
ground to pin/cavity A-12 (circuit K78) directly at PCM, replace PCM.
