Idle Air Controller plunger not retracting
Thread Starter
Newbie
Joined: Nov 2011
Posts: 1
Likes: 0
Model: Cherokee
Idle Air Controller plunger not retracting
The jeep is a 1991 XJ with 4.0L and the automatic transmission. The Issue: will not idle until the engine warms up a bit, then runs fine. This morning I replaced the Idle Air Controller in the parking lot of the auto parts store. The engine was still cold and it was about 15 degrees outside. It started just fine, however I just went start it and the issue has returned. So I pulled off the IAC and the plunger was still fully extended, it didn't retract. I pushed the plunger back and it started and idled again, and I let the engine warm up and cool down again. Once again the plunger is fully extended. I just checked my MAP sensor and it seems to be working. The TPS is brand new. The fuel system except the injectors is new as well (different issue). I've also checked for cracked or broken vacuum lines, replaced two. I want to do an electrical test for the IAC to see if my signals are correct but I'm having a hard time finding the proper values. Any advice? Thanks in advance.
CF Veteran
Joined: Oct 2018
Posts: 1,096
Likes: 166
From: Hunt County Texas
Year: 1995
Model: Cherokee (XJ)
Engine: 4.0L
What brand IAC is that? Some of the big box parts store's electrical parts for the XJ are known to sometimes be DOA out of the box.
FWIW the FSM (for a 95) requires an "exerciser tool". I'm sure you could build one but I'm not sure if you can buy one anywhere. It doesn't mention anything about proper values. The only way I can think to test it is to remove it switch the key to on and see if the pintle retracts. After that it's ruling out any chafed or damaged wires and making sure your grounds are good to go. If all that checks out you may have just got a bad one out of the box.
FWIW the FSM (for a 95) requires an "exerciser tool". I'm sure you could build one but I'm not sure if you can buy one anywhere. It doesn't mention anything about proper values. The only way I can think to test it is to remove it switch the key to on and see if the pintle retracts. After that it's ruling out any chafed or damaged wires and making sure your grounds are good to go. If all that checks out you may have just got a bad one out of the box.
IDLE AIR CONTROL MOTOR TEST
Idle air control (IAC) motor operation can be tested
using special exerciser tool number 7558 (Fig. 41).
CAUTION: Proper safety precautions must be taken
when testing the idle air control motor:
² Set the parking brake and block the drive wheels
² Route all tester cables away from the cooling fans,
drive belt, pulleys and exhaust components
² Provide proper ventilation while operating the engine
² Always return the engine idle speed to normal before
disconnecting the exerciser tool
(1) With the ignition OFF, disconnect the IAC motor
wire connector at throttle body (Fig. 41).
(2) Plug the exerciser tool number 7558 harness
connector into the IAC motor.
(3) Connect the red clip of exerciser tool 7558 to
battery positive terminal. Connect the black clip to
negative battery terminal. The red light on the exerciser
tool will flash when the tool is properly connected.
(4) Start engine.
When the switch on the tool is in the HIGH or
LOW position, the light on the tool will flash. This
indicates that voltage pulses are being sent to the
IAC stepper motor.
(5) Move the switch to the HIGH position. The engine
speed should increase. Move the switch to the
LOW position. The engine speed should decrease.
(a) If the engine speed changes while using the
exerciser tool, the IAC motor is functioning properly.
Disconnect the exerciser tool and connect the
IAC motor wire connector to the stepper motor.
(b) If the engine speed does not change, turn the
ignition OFF and proceed to step (6). Do not disconnect
exerciser tool from the IAC motor.
(6) Remove the IAC motor from the throttle body.
Do not remove IAC motor housing from throttle body.
CAUTION: When checking IAC motor operation with
the motor removed from the throttle body, do not
extend the pintle (Fig. 42) more than 6.35 mm (.250
in). If the pintle is extended more than this amount,
it may separate from the IAC motor. The IAC motor
must be replaced if the pintle separates from the
motor.
(7) With the ignition OFF, cycle the exerciser tool
switch between the HIGH and LOW positions. Observe
the pintle. The pintle should move in-and-out
of the motor.
(a) If the pintle does not move, replace the idle
air control motor. Start the engine and test the replacement
motor operation as described in step (5).
(b) If the pintle operates properly, check the idle
air control motor bore in the throttle body bore for
blockage and clean as necessary. Reinstall the idle
air control motor and retest. If blockage is not
found, refer to the DRB scan tool and the appropriate
Powertrain Diagnostics Procedures service
manual.
Fig. 40 Oxygen Sensor—Typical
Fig. 41 IAC Motor Testing—Typical
Fig. 42 Idle Air Control (IAC) Motor Pintle
Idle air control (IAC) motor operation can be tested
using special exerciser tool number 7558 (Fig. 41).
CAUTION: Proper safety precautions must be taken
when testing the idle air control motor:
² Set the parking brake and block the drive wheels
² Route all tester cables away from the cooling fans,
drive belt, pulleys and exhaust components
² Provide proper ventilation while operating the engine
² Always return the engine idle speed to normal before
disconnecting the exerciser tool
(1) With the ignition OFF, disconnect the IAC motor
wire connector at throttle body (Fig. 41).
(2) Plug the exerciser tool number 7558 harness
connector into the IAC motor.
(3) Connect the red clip of exerciser tool 7558 to
battery positive terminal. Connect the black clip to
negative battery terminal. The red light on the exerciser
tool will flash when the tool is properly connected.
(4) Start engine.
When the switch on the tool is in the HIGH or
LOW position, the light on the tool will flash. This
indicates that voltage pulses are being sent to the
IAC stepper motor.
(5) Move the switch to the HIGH position. The engine
speed should increase. Move the switch to the
LOW position. The engine speed should decrease.
(a) If the engine speed changes while using the
exerciser tool, the IAC motor is functioning properly.
Disconnect the exerciser tool and connect the
IAC motor wire connector to the stepper motor.
(b) If the engine speed does not change, turn the
ignition OFF and proceed to step (6). Do not disconnect
exerciser tool from the IAC motor.
(6) Remove the IAC motor from the throttle body.
Do not remove IAC motor housing from throttle body.
CAUTION: When checking IAC motor operation with
the motor removed from the throttle body, do not
extend the pintle (Fig. 42) more than 6.35 mm (.250
in). If the pintle is extended more than this amount,
it may separate from the IAC motor. The IAC motor
must be replaced if the pintle separates from the
motor.
(7) With the ignition OFF, cycle the exerciser tool
switch between the HIGH and LOW positions. Observe
the pintle. The pintle should move in-and-out
of the motor.
(a) If the pintle does not move, replace the idle
air control motor. Start the engine and test the replacement
motor operation as described in step (5).
(b) If the pintle operates properly, check the idle
air control motor bore in the throttle body bore for
blockage and clean as necessary. Reinstall the idle
air control motor and retest. If blockage is not
found, refer to the DRB scan tool and the appropriate
Powertrain Diagnostics Procedures service
manual.
Fig. 40 Oxygen Sensor—Typical
Fig. 41 IAC Motor Testing—Typical
Fig. 42 Idle Air Control (IAC) Motor Pintle
CF Veteran
Joined: Oct 2018
Posts: 1,096
Likes: 166
From: Hunt County Texas
Year: 1995
Model: Cherokee (XJ)
Engine: 4.0L
Call your local Jeep dealer with this P/N and see what they can get it for. factorychrylserparts.com has it for 66 bucks (unknown shipping costs though).
04798377 If I'm reading the parts list right this fits 91-96 or 97 XJs.
04798377 If I'm reading the parts list right this fits 91-96 or 97 XJs.
Thread
Thread Starter
Forum
Replies
Last Post
PurringRaccoon
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
3
Jul 2, 2012 03:30 PM
bridge9
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
1
Mar 18, 2011 10:14 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)