Engine Controls - High Idle Speed
87chevy21Number: REISSUE 86-252-6E
Section: 6E
Date: OCT., 1987
Subject: HIGH IDLE SPEED
Model and Year: 1986 CELEBRITY WITH 2.8L (VIN X) ENGINE
TO: ALL CHEVROLET DEALERS
Dealer service bulletin 86-252 (Section 6E) dated Sept. 1987 is being reissued to provide additional charts. All copies of 86-252, dated Sept. 87, should be destroyed.
The ECM will turn "on" the vacuum throttle kicker solenoid if TPS or idle speed are adjusted above specification; which will result in a high idle speed.
If a high idle speed is noted, follow TPS and/or idle speed adjustment procedures in the service manual. TPS should be .30 volts with kicker solenoid plunger retracted.
The new charts included with this bulletin supersedes the 1986 service manual charts.
CHART C-2E-1
VACUUM THROTTLE KICKER 2.8L (CARB)
Circuit Description: (1 OF 2) "Throttle Kicker" is vacuum operated and extends under the following conditions:
^ Coolant temperature below 85~C (185~F).
^ For 30 seconds after start if coolant temperature above 85~C (185~F).
^ A/C "ON" and pressure cycling switch closed (clutch "ON").
^ Full turn (power steering switch open.)
CHART C-2 E-1VACUUM THROTTLE KICKER 2.8L (CARB) (1 OF 2):
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. Checks ECM control of kicker solenoid and for an open in kicker relay coil circuit. TPS should be .30 volts with kicker solenoid plunger retracted and idle speed set to specifications. If TPS and idle speed are above specification, the ECM will energize the kicker solenoid.
2. Checks for open kicker relay coil circuit to ECM.
3. Checks for open ignition circuit to kicker solenoid.
4. Checks for open in CKT 900 from relay to kicker. This includes poor connections.
5. Checks vacuum source to solenoid, then checks for faulty kicker.
6. Checks to see that power steering switch opens, and the kicker relay contact circuit is not open.
7. Checks for grounded WOT relay coil circuit or sticking relay points.
8. Checks for grounded WOT relay coil circuit.
CHART C-2E-2
VACUUM THROTTLE KICKER 2.8L (CARB) (2 OF 2)
CHART C-2 E-2"VACUUM THROTTLE KICKER"2.8L (CARB) (2 OF 2):
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
9. Checks for faulty throttle kicker actuator.
10. If kicker retracts, kicker relay or circuit is cause of problem.
11. "No light" indicates an open kicker relay coil circuit.
12. Checks for a faulty kicker solenoid, grounded CKT 900 to solenoid or faulty ECM.