S10/T10 P/U 4WD V6-173 2.8L (1986)
Throttle Position Sensor: Customer Interest
Engine Controls - MIL On or Erratic Idle
Number:
86-145
Section:
6D
Date:
AUG., 1986
Subject:
ERRATIC IDLE AND SERVICE MANUAL REVISION
Model and Year:
1986 S/T TRUCKS WITH 2.8L (VIN CODE R) TBI ENGINES
TO:
ALL CHEVROLET DEALERS
Some 1986 S/T trucks equipped with the 2.8L TBI engine may experience an erratic idle condition or a "Service Engine Soon" Light that stays on. This
condition may be caused by the Throttle Position Sensor (TPS) supplying incorrect voltages to the Electronic Control Module (ECM). A voltage test of
the TPS switch must be made prior to replacement of the TPS using the Service manual revision included in this bulletin.
If this condition is encountered and the testing indicates TPS replacement is necessary, a new TPS, P/N 17111725, has been released and should be used
to correct this condition. The replacement procedures for this operation can be found in Section 6E2-C2-15 of the S10 Service Manual. When
performing the TPS voltage check, a revision must be made to the adjustment procedure on page 6E2-C2-15.
The revision should read as follows:
With ignition "ON", voltage between terminals "A" and "B" should be between 0.420 and 0.450 volts.