TPS - Auto Zeroing Update
Number 87-6(Gasoline)-73 Date 10/87Subject: AUTO-ZEROING TPS - SECTION 6E1
1987 GRAND PRIX AND FIREBIRD MODELS EQUIPPED WITH 5.0L ENGINE (VIN CODE H)
The ECM has the ability to auto-zero the TPS voltage if it is below .84 volts. 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 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 supersedes the information printed in the 1987 Service Manuals.