Copyright © 1998 General Motors Corp. 6–33
WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL
Main code 22 indicates a fault within a speed sensor, the wiring to a speed sensor, incorrect speed sensor gap, or
damaged bumps or teeth which create the speed signal. This fault is determined by the reasonableness of a speed
sensor signal when compared with the other two speed sensors and the commanded range. A speed sensor will not
pass the reasonableness test if there is no signal at all from that sensor when a signal should be present.
NOTE: If the engine speed sensor code (22 14) is active and a range verification test is failed, the range
verification code will not be set but a DO NOT SHIFT response is commanded.
Active Indicator Clearing Procedure:
• Power down
• Manual
• Self-clearing
NOTE: Before troubleshooting, read Pages 6–17 and 6–18 of Section 6–5. Also, check the ECU input voltage.
Troubleshooting:
1. Check to see if the sensor is loose, missing, or disconnected. If not, disconnect the wiring harness
from the sensor and measure the resistance of the sensor (see chart below). Also check the
terminals for dirt, corrosion, or damage. If resistance is not correct, replace the sensor.
2. Remove the connectors from the ECU. Check the sensor circuit (in the external harness) for open
wires, shorts between wires, or shorts-to-ground. Isolate and repair any faults (refer to Appendix E
for repair information).
3. If no opens or shorts are found, the condition must be intermittent. Replace the sensor indicated by
the trouble code. Before replacing a speed sensor, check the sensor for physical damage or
contamination. Refer to the appropriate transmission Service Manual for proper replacement
procedure.
4. If the condition recurs, install new wiring (twisted-pair) for the sensor circuit between the ECU
and the transmission. Use P/N 29522703 Service Harness Twisted Shielded Pair for this purpose.
5. If the condition again recurs, connect the diagnostic tool and select the speed signal indicated by
the trouble code. Drive the vehicle and watch the speed reading on the diagnostic tool. If the signal
is erratic, sensor gap, vehicle vibration, an external AC signal source, or intermittent connector
Main Code Subcode Failed Sensor
22 14 Engine Speed
22 15 Turbine Speed
22 16 Output Speed
Resistance Temp. °C Temp. °F
200 Ω –40 –40
300 Ω 20 68
400 Ω 110 230
CODE 22 XX — SPEED SENSOR/CIRCUITRY FAULT (Figures 6–7, 6–8)
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