Idle Load Compensator - Service Manual Revision
87pontiac15 Number 87-6(Gasoline)-79 Date 12/87SERVICE MANUAL REVISION - CHART C-2C, Subject: "IDLE LOAD COMPENSATOR (ILC) CHECK"
1986 PARISIENNE WAGON AND 1987 SAFARI WAGON
The attached replaces the published information in the 1986 and 1987 Service Manuals.
The C-2C facing page artwork has been changed to show all the components between the ILC/RVB/EGR solenoid assembly and idle load compensator. The C-2C diagnostic chart has been reworked to more thoroughly diagnose any failure of components within the ILC vacuum and electrical system.
Please replace the original charts with those attached.
CHART C-2CIDLE LOAD COMPENSATOR (ILC) CHECK 5.0L (VIN Y) (CARB):
CHART C-2C
IDLE LOAD COMPENSATOR (ILC) CHECK 5.0L (VIN Y) (CARB)
Circuit Description:
The idle load compensator (ILC) is mounted on the carburetor and is used to control various low engine rpm conditions. The ILC uses a spring loaded vacuum sensitive diaphragm whose plunger extends when vacuum is not present. Vacuum to the ILC is controlled by the ECM through the ILC/RVB/EGR solenoid assembly. When the ECM turns "ON" the ILC solenoid assembly, vacuum is cut "OFF" to the ILC. Vacuum is regulated through the VRV and delayed under high load conditions (checked) by the DVDV and through the Anti-diesel solenoid (ADS). The ADS is energized when the IGN is turned "ON", allowing vacuum to the ILC, and turned "OFF" when the IGN is "OFF". This supplies vacuum to the ILC, keeping the plunger retracted so the engine can shut down without dieseling.
CHART C-2CIDLE LOAD COMPENSATOR (ILC) CHECK 5.0L (VIN Y) (CARB):
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. ILC plunger should be extended as no vacuum is being applied.
2. LC plunger should retract if vacuum is applied.
3. Depressing the TPS should make the ECM turn the ILC quad-driver "ON", blocking vacuum to the ILC, and simulating a W.O.T. condition. Clear long term memory after this procedure, as the ECM must relearn correct TPS voltage.
4. With test terminal grounded, ECM should be turning "ON" ILC solenoid assembly. Test light should be "ON".
5. Anti-diesel solenoid is energized any time ignition is "ON", so test light should be "ON".
6. Test light should be "OFF", as ILC quad-driver should be turned "OFF".
7. If the test light goes out, the ECM has to be replaced, as the quad-driver inside the ECM has failed.