ECM - Ability to Auto-Zero TPS Voltage
87chevy20Number: 87-233
Section: 6E
Date: Oct., 1987
Subject: ECM ABILITY TO AUTO-ZERO
THROTTLE POSITION SENSOR VOLTAGE
Model and Year: 1987 CAPRICE, MONTE CARLO, CAMARO, EL CAMINO, WITH 5.0L, 5.7L (VIN G, H, 6) ENGINE
TO: ALL CHEVROLET DEALERS
The ECM has the ability to auto-zero the TPS voltage if it is below .84 volts (VINS G and H) and 1.1 volts (VIN 6). This means that any voltage less than the voltages above will be determined by the ECM to be 0% (closed) throttle. "Scan" tools that have the ability to read the throttle blade angle should read 0% when the throttle is closed. A failure in the TPS circuit should set a code 21.
If the voltage is within the specified range of below .84 volts (VINS G and H) and below 1.1 volts (VIN 6) no adjustment is necessary.
If the voltage is greater than the preceding specification or a new TPS is installed, follow the adjustment procedure in the service manual and adjust to .5V +/- .05.
This information supercedes the information printed in the 1987 service manuals, Section 6E1.