NTC-4: Speed Control On/Off Switch

Possible Causes:

• Ground circuit open.
• Speed control SET/RESUME switch voltage more than 4 volts.
• Speed control switch signal circuit shorted to voltage or ground.
• Speed control ON/OFF switch voltage less than one volt or more than 4 volts.
• Defective PCM.
• Defective clockspring.

1. Turn ignition off. Disconnect PCM connectors. Disconnect clockspring 5-pin connector located behind steering wheel. Inspect connectors. Clean or repair connectors as necessary. Using DVOM, check resistance of speed control switch signal circuit between PCM connector C2, terminal No. 41 and clockspring 5-pin connector, terminal No. 4 (Red/Light Green wire). If resistance is 5 ohms or more, repair open circuit. Perform TEST VER-4A  under VERIFICATION TESTS. If resistance is less than 5 ohms, go to next step.
2. Reconnect clockspring. Disconnect speed control ON/OFF switch connector. Inspect connector. Clean or repair connector as necessary. Using DVOM, check resistance of speed control switch ground circuit at speed control ON/OFF switch connector Black wire. If resistance is 5 ohms or more, repair open ground circuit. Perform TEST VER-4A  under VERIFICATION TESTS. If resistance is less than 5 ohms, go to next step.
3. Reconnect PCM. Connect a jumper wire across speed control ON/OFF switch terminals. Turn ignition on. Using scan tool, read speed control switch voltage. If scan tool displays zero volts or OFF, replace speed control ON/OFF switch. Perform TEST VER-4A  under VERIFICATION TESTS. If scan tool does not display zero volts or OFF, go to next step.
4. Disconnect PCM connectors. Using DVOM, check resistance of speed control switch signal circuit between speed control ON/OFF switch White wire and PCM connector C2, terminal No. 41 (Red/Light Green wire). If resistance is less than 5 ohms, replace PCM. Perform TEST VER-4A  under VERIFICATION TESTS. If resistance is 5 ohms or more, go to next step.
5. Using DVOM, check resistance between ground and speed control switch signal circuit at speed control ON/OFF switch White wire. If resistance is less than 5 ohms, repair short to ground. Perform TEST VER-4A  under VERIFICATION TESTS. If resistance is 5 ohms or more, go to next step.
6. Inspect speed control ON/OFF switch connector. If any terminal is damaged, pushed out or miswired, repair connector as necessary. If terminals are okay, replace clockspring. See AIR BAG RESTRAINT SYSTEMS - TRUCKS article. Perform TEST VER-4A  under VERIFICATION TESTS.