To Set Speed Control
Press ON/OFF button to turn speed control system on. Accelerate to desired speed (minimum of 35 MPH) and press SET/COAST button. Vehicle speed will be maintained.
Note. Speed control system will automatically disengage when vehicle speed decreases to less than 35 MPH or increases to more than 85 MPH.
To Disengage Speed Control
Press brake pedal. Press clutch pedal (M/T). Press CANCEL button. Press ON/OFF button. If ON/OFF button is used, set speed will be erased from memory.
To Resume Previous Speed
If set speed has not been erased from memory and vehicle speed is more than 35 MPH, press RES/ACCEL button.
To Increase Speed
With speed control system on, increase set speed by rapidly pressing and releasing RES/ACCEL button. Each pressing of button will cause speed increase of 2 MPH. For example, pressing button 3 times will increase speed by 6 MPH. To increase speed gradually, hold RES/ACCEL button down until desired speed is reached. When button is released, new set speed will be maintained.
To Decrease Speed
With speed control system on, decrease set speed by pressing SET/COAST button. Vehicle speed will gradually decrease. Releasing button will set a new speed as long as vehicle speed is still more than 35 MPH.
OVERSHOOT/UNDERSHOOT FOLLOWING SPEED CONTROL SET
If operator repeatedly presses and releases set button with their foot off accelerator (lift foot set) to begin speed control operation, vehicle may accelerate and exceed desired set speed by 5 MPH and then decelerate to less than desired set speed before achieving desired set speed.
Speed Control (S/C) has as adaptive strategy that compensates for variations in S/C cable lengths. When S/C is set with vehicle operator's foot off accelerator pedal, S/C compensates for excessive S/C cable slack. If lift foot sets are continually used, speed control overshoot/undershoot condition will develop.
To "unlearn" overshoot/undershoot condition, operator must press and release set button while maintaining desired speed with accelerator pedal, then turn S/C switch to OFF position after waiting 10 seconds. This procedure must be repeated 10-15 times to completely unlearn overshoot/undershoot condition.
SERVICE PRECAUTIONS
Before proceeding with diagnosis, the following precautions must be followed
- When using Diagnostic Trouble Code (DTC) tests for diagnosis, DO NOT skip any steps, or incorrect diagnosis may result. Always perform indicated verification procedure after repairs are made.
- When using a jumper wire, ensure either jumper wire or circuit is fuse-protected.
- Before disconnecting connector from any control module, ensure ignition is off before removing connector.
- When checking voltage or continuity at any control module, probe connector for control module from pin side. DO NOT backprobe connector or probe wires through insulation.
- DO NOT cause short circuits when performing electrical tests. This will set additional Diagnostic Trouble Codes (DTCs), making diagnosis of original problem more difficult.
- Use specified test equipment when performing electrical tests.
SYSTEM TESTS
Note. For component locations, See COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS .
NTC-1: BRAKE SWITCH SENSE
Possible Causes
- Ground circuit open.
- Defective brake switch.
- Brake switch sense circuit open or shorted.
- Defective PCM.
- Turn ignition off. Disconnect brake switch connector. Inspect connector. Clean or repair connections as necessary. Turn ignition on. Using a voltmeter, measure voltage of brake switch sense circuit at brake switch White/Pink wire. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, go to step 3 .
- Connect a jumper wire between ground and brake switch connector White/Pink wire. Using scan tool, read brake switch input status. If scan tool displays brake switch released, replace brake switch. If scan tool does not display brake switch released, repair open ground circuit. After repair, perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
- Disconnect PCM connectors. Inspect connectors. Clean or repair connections as necessary. Using an ohmmeter, measure resistance between ground and brake switch sense circuit at PCM connector C3, terminal No. 24 (White/Pink wire). If resistance is 5 ohms or more, go to next step. If resistance less than 5 ohms, repair short to ground. Perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
- Using an ohmmeter, measure resistance of brake switch sense circuit between PCM connector C3, terminal No. 24 and brake switch (White/Pink wire). If resistance is 5 ohms or more, repair open brake switch sense circuit. If resistance is less than 5 ohms, replace PCM. After repair, perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
NTC-2: CHECKING FOR SPEED CONTROL DENIED MESSAGE
At this time, speed control switch and servo functions appear to operate properly. Using scan tool, monitor speed control output status. Road test vehicle at speeds more than 35 MPH. Attempt to set speed control. See SCAN TOOL DENIED STATUS table. Items listed in table will not allow speed control to set. The last or most recent cause for speed control not to set is indicated by denied status. Correct fault and recheck system operation.
| Denied Message | Reason |
|---|---|
| ON/OFF | No ON Signal From Switch At PCM Terminal No. 41 |
| SPEED | Vehicle Speed Is Not Greater Than 36 MPH At PCM Terminal No. 66 |
| RPM | Engine RPM Is Excessively High |
| BRAKE | Brake Switch Sense Circuit Is Open Indicating That Brakes Are Applied |
| P/N | Park/Neutral Switch Sense Circuit Is Grounded Indicating That Transmission Is In Park Or Neutral |
| RPM/SPD | PCM Senses Excessive Engine RPM For A Given Vehicle Speed |
| SOL FLT | PCM Senses A Servo Solenoid Circuit Trouble Code That Is Maturing Or Set In Memory |
SCAN TOOL DENIED STATUS
NTC-3: SPEED CONTROL ON/OFF SWITCH
Possible Causes
- Signal circuit open or shorted.
- S/C ON/OFF switch defective.
- S/C RESUME/ACCEL switch defective.
- Defective PCM.
- Defective clockspring.
- Turn ignition on. Using scan tool, read S/C switch voltage. If voltage is more than 4 volts, go to next step. If voltage is 4 volts or less, go to step 4 .
- Turn ignition off. Disconnect S/C ON/OFF switch. Inspect connector. Clean or repair connections as necessary. Connect a jumper wire between ground and S/C switch signal circuit at S/C ON/OFF switch connector (Dark Green/Red wire on all models except Ram Van and Ram Wagon; wire color is not available for Ram Van and Ram Wagon). Start engine. Turn speed control on. Using scan tool, read S/C switch voltage. If voltage is one volt or more, go to next step. If voltage is less than one volt, replace S/C ON/OFF switch. Perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
- Using a voltmeter, measure voltage on S/C switch signal circuit (Dark Green/Red wire on all models except Ram Van and Ram Wagon; wire color is not available for Ram Van and Ram Wagon). If voltage is less than 4 volts, repair high resistance in S/C switch signal circuit. If voltage is more than 6 volts, repair short to voltage. If voltage is 4-6 volts, replace PCM. After repair, perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
- Turn ignition off. Disconnect clockspring connector at steering column. Start engine. Turn speed control on. Using scan tool, read S/C switch voltage. If voltage is 4 volts or less, go to next step. If voltage is more than 4 volts, replace clockspring. Perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
- Turn ignition off. Disconnect RESUME/ACCEL switch. Start engine. Turn speed control on. Using scan tool, read S/C switch voltage. If voltage is 4 volts or less, go to next step. If voltage is more than 4 volts, replace RESUME/ACCEL switch. Perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
- Turn ignition off. Disconnect S/C ON/OFF switch. Start engine. Using scan tool, turn speed control on. Using scan tool, read S/C switch voltage. If voltage is 4 volts or less, go to next step. If voltage is more than 4 volts, replace ON/OFF switch. Perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
- Turn ignition off. Disconnect PCM. Inspect connectors. Clean or repair connections as necessary. Using an ohmmeter, measure resistance between ground and S/C switch signal circuit at PCM connector C3, terminal No. 32 (White/Light Green wire on Ram Van and Ram Wagon; Red/Light Green wire on all other models). If resistance is less than 5 ohms, repair short to ground. If resistance is 5 ohms or more, replace PCM. After repair, perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
NTC-4: SPEED CONTROL RESUME/ACCEL SWITCH
Possible Causes
- Ground circuit open.
- RESUME/ACCEL switch defective.
- Signal circuit open.
- Turn ignition off. Disconnect S/C RESUME/ACCEL switch. Inspect connectors. Clean or repair connections as necessary. Connect a jumper wire between ground and S/C switch signal circuit at RESUME/ACCEL switch connector (Dark Green/Red wire on all models except Ram Van and Ram Wagon; wire color is not available for Ram Van and Ram Wagon). Turn ignition on. Using scan tool, read S/C switch voltage. If voltage is one volt or more, go to next step. If voltage is less than one volt, replace RESUME/ACCEL switch. Perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
- Turn ignition off. Using an ohmmeter connected to ground, check resistance of RESUME/ACCEL switch ground circuit at RESUME/ACCEL switch connector. If resistance is 5 ohms or more, repair open ground circuit. If resistance is less than 5 ohms, repair open S/C switch signal circuit. After repair, perform «TEST VER-4A»(ref-3601-S34181773902000051100000) under VERIFICATION TESTS.
COMPONENT TESTS
| WARNING | Vehicle is equipped with an air bag. Air bag must be deactivated before servicing speed control components on or around steering column. See appropriate AIR BAG RESTRAINT SYSTEMS article. |
Note. For component locations, See COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS .
BRAKE SWITCH
Disconnect brake switch 6-pin connector. Using an ohmmeter, check for continuity at brake switch. (Схема №1) If continuity is not as specified in BRAKE SWITCH CONTINUITY table, replace defective brake switch. See BRAKE SWITCH under REMOVAL & INSTALLATION.
| Switch Plunger Position | Continuity Between Terminals No. |
|---|---|
| Depressed | 1 & 2 |
| Released | 3 & 4 |
| Released | 5 & 6 |
BRAKE SWITCH CONTINUITY
SPEED CONTROL SERVO
- Start engine. Disconnect Speed Control (S/C) servo 4-pin connector. Turn S/C on. Using a voltmeter, check voltage at S/C servo connector terminal No. 3 (Dark Blue/Red wire). Battery voltage should exist when brake pedal is not depressed. If battery voltage exists, go to next step. If battery voltage does not exist, check circuit between brake switch and S/C servo. See «WIRING DIAGRAMS»(ref-3601-S02789509972000051100000) .
- Connect a jumper wire between S/C servo pin No. 3 and S/C servo connector terminal No. 3. Check voltage at S/C servo pins No. 1, 2 and 4. If battery voltage does not exist, replace S/C servo. If battery voltage exists, go to next step.
- Turn ignition off. Check for continuity between S/C servo connector terminal No. 4 and ground. If continuity exists, test is complete. If continuity does not exist, repair open ground circuit as necessary.
Gasoline Engines
- Disconnect vacuum hose at speed control servo. Install vacuum gauge to disconnected vacuum hose. Start engine and observe gauge. Vacuum reading should be a minimum of 10 in. Hg. Turn engine off. Vacuum should continue to hold at a minimum of 10 in. Hg.
- If vacuum is not as specified, check for kinked or leaking vacuum lines, defective check valve, defective vacuum reservoir or poor engine performance. If no problems are found, check speed control servo. See «SPEED CONTROL SERVO»(ref-3601-S41906651432000051100000) .
Diesel Engines
- Disconnect vacuum hose at speed control servo. Install vacuum gauge to disconnected vacuum hose. Start engine and observe gauge. Vacuum reading should be a minimum of 25 in. Hg. A vacuum reservoir is not used on diesel vehicles.
- If vacuum is not as specified, disconnect vacuum supply hose from vacuum pump. Install vacuum gauge to vacuum pump. Start engine and observe gauge. If vacuum reading is not 25 in. Hg or more, replace vacuum pump. If vacuum reading 25 in. Hg or more, go to next step.
- Check all vacuum hoses to speed control servo, vacuum pump and heater-A/C system for leaks. Check vacuum check valve for leaks and proper operation. Vacuum check valve is located in vacuum hose between speed control servo and vacuum pump. If no problems are found, check speed control servo. See «SPEED CONTROL SERVO»(ref-3601-S41906651432000051100000) .