LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1985 >> Forward Control 5.7 M, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Diesel CEC Tests W/Codes >> Code 22 - TPS Grounded Or MISADJUSTED
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Code 22 - TPS Grounded Or MISADJUSTED

The Throttle Position Sensor (TPS) is a variable resistor that supplies the ECM with throttle opening information. The sensor is supplied with a 5-volt reference signal. Sensor resistance is highest (low signal to ECM) at closed throttle.

Code 22 means that the ECM has seen low voltage at terminal "A2" for more than 2 minutes with engine speed over 1250 RPM.

NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s).
  1. Confirms that code is still present.
  2. Checks for reference voltage at TPS harness connector to determine whether problem is electrical circuit or faulty TPS. If circuit is OK, normal voltage reading will be about 5 volts.
Fig 1: Flow Chart, Code 22, TPS Grounded Or Misadjusted
G10289
Fig 2: Flow Chart, Code 22, TPS Grounded Or Misadjusted
GB0046431