DDEC III/IV Single ECM Troubleshooting – Section 10.7 Cruise Control Inoperative

Section 10.7
Cruise Control Inoperative

Before using this procedure, all basic mechanical checks and physical inspections should have been performed with no problem found. Also the diagnosis of the DDEC system in Section 9 referred you to this section.‪

Section 10.7.1
Determine Type of Cruise Control System

Perform the following to determine the type of cruise control system:‪

1. Check that this is a DDEC cruise control system.
2. Turn ignition ON.
3. Plug DDR into DDL connector.
4. Select calibration configuration (cruise control).
5. Is cruise control enabled?
   1. If cruise control is enabled, refer to "10.7.3 Check Pin Assignments" .
   2. If cruise is not enabled, refer to DDEC III Installation and Application manual, 7SA800, for requirements of installing cruise control.

Section 10.7.2
Check ECM Connectors

Perform the following to check the ECM connectors:‪

1. Disconnect the vehicle harness connector at the ECM.
2. Check the terminals at the ECM vehicle harness connector (both ECM and harness side) for damaged, corroded, or unseated pin or sockets.
   1. If terminals and connectors are not damaged, reprogram the ECM. Refer to "10.7.16 Verify Repairs" .
   2. If the terminals or connectors are damaged, repair them. Refer to "10.7.16 Verify Repairs" .

Section 10.7.3
Check Pin Assignments

Perform the following to check pin assignments:‪

1. Turn ignition ON.
2. Plug in the DDR.
3. Select calibration configuration (ECM Ins/Outs).
4. Write/print pin assignments.
   1. An example listed in Table "Pin Assignments" shows pins, wires and functions. Refer to "10.7.4 Checking Out of Cruise Control Switch and Wiring" .

   Pin ‪	Wire ‪	Function ‪
   J1‪	#541‪	set/coast on‪
   F2‪	#544‪	cruise enable‪
   G2‪	#543‪	svc brk rel‪
   J2‪	#531‪	clutch rel‪
   G3‪	#545‪	res/accel on‪

   Table 1. Pin Assignments
   2. If the functions are not assigned, reprogram the ECM. Refer to "10.7.16 Verify Repairs" .

Section 10.7.4
Checking Out of Cruise Control Switch and Wiring

To speed up the checking out of cruise control switches, quick check tables have been developed. These tests are to be run with the ignition ON, and the engine not running. A DDR must be plugged into the connector. All three quick check tables must be gone through to completely check out the cruise control wiring and switches.‪

For Example: Listed in Table "Cruise Control Quick Check Table I, Check Out Cruise Enable Switch and Wiring (Ignition ON Not Running)" , step 2, you would do the following:‪

1. Ignition ON; engine not running; DDR plugged in.
2. Turn the cruise enable switch to ON.
3. Select switch/light status on the DDR.
4. Note the DDR display; if ON, check out brake and clutch switch as listed in Table "Cruise Control Quick Check Table II, Check Out Brake and Clutch Switch and Wiring (Ignition ON Not Running)" .

   Step ‪	Cruise Enable Switch ‪	Set / Coast Switch ‪	Res / Accel Switch ‪	DDR Readout Being Looked At ‪	DDR Display ‪	Okay ‪	Go To ‪
   1.‪	Off‪	Off‪	Off‪	Cruise Enable‪	Off‪ On‪	Yes‪ No‪	Refer to step 2;‪ Refer to "10.7.5 Check for Short at the Cruise Enable Circuit" ‪
   2.‪	On‪	Off‪	Off‪	Cruise Enable‪	Off‪ On‪	No‪ Yes‪	Refer to "10.7.6 Check for Open at the Cruise Enable Circuit" ;‪ Listed in Table "Cruise Control Quick Check Table II, Check Out Brake and Clutch Switch and Wiring (Ignition ON Not Running)" , step 1‪

   Table 2. Cruise Control Quick Check Table I, Check Out Cruise Enable Switch and Wiring (Ignition ON Not Running)

   Step ‪	Cruise Enable Switch ‪	Brake Pedal ‪	Clutch Pedal ‪	DDR Readout Being Looked At ‪	DDR Display ‪	Okay ‪	Go To ‪
   1.‪	On‪	Released‪	Released‪	Service Brake Release‪	On‪ Off‪	Yes‪ No‪	Refer to step 2‪ Refer to "10.7.7 Check for Open or Miswired Brake Switch" ‪
   2.‪	On‪	Depressed‪	Released‪	Service Brake Release‪	On‪ Off‪	No‪ Yes‪	Refer to "10.7.8 Check for Short at the Brake Switch or Circuit" ‪ Refer to step 3‪
   3.‪	On‪	Released‪	Released‪	Clutch Release‪	On‪ Off‪	Yes‪ No‪	Refer to step 4‪ Refer to "10.7.9 Check for Open or Miswired Clutch Switch" ‪
   4.‪	On‪	Released‪	Depressed‪	Clutch Release‪	On‪ Off‪	No‪ Yes‪	Refer to "10.7.10 Check for Short at the Clutch Service/Circuit" ;‪ Listed in Table "Cruise Control Quick Check Table III, Check Out Set/Coast and Resume/Accel Switches and Wiring (Ignition ON Not Running)" , step 1‪

   Table 3. Cruise Control Quick Check Table II, Check Out Brake and Clutch Switch and Wiring (Ignition ON Not Running)

   Step ‪	Cruise Enable Switch ‪	Set / Coast Switch ‪	Res / Accel Switch ‪	DDR Readout Being Looked At ‪	DDR Display ‪	Okay ‪	Go To ‪
   1.‪	On‪	Off‪	Off‪	Set/Coast‪ On‪	Off‪ On‪	Yes‪ No‪	Refer to step 2‪ Refer to "10.7.11 Check for Short at the Set/Coast Circuit" ‪
   2.‪	On‪	On‪	Off‪	Set/Coast‪ On‪	Off‪ On‪	No‪ Yes‪	Refer to "10.7.12 Check for Open at the Set/Coast Circuit" ‪ Refer to step 3‪
   3.‪	On‪	Off‪	Off‪	Res/Accel‪ On‪	Off‪ On‪	Yes‪ No‪	Refer to step 4‪ Refer to "10.7.13 Check for Short at the Res/Accel Circuit" ‪
   4.‪	On‪	Off‪	On‪	Res/Accel‪ On‪	Off‪ On‪	No‪ Yes‪	Refer to "10.7.14 Check for Open at the Res/Accel Circuit" ‪ Refer to "10.7.15 Verify Problem Still Exists" ‪

   Table 4. Cruise Control Quick Check Table III, Check Out Set/Coast and Resume/Accel Switches and Wiring (Ignition ON Not Running)

Section 10.7.5
Check for Short at the Cruise Enable Circuit

Perform the following steps to check for a short at the cruise enable circuit:‪

1. Turn ignition ON.
2. Turn cruise engage switch to off.
3. Disconnect the vehicle harness connector at the ECM.
4. Measure resistance between the cruise enable cavity (i.e. F2) on the vehicle harness connector and a good ground.
   1. If the resistance measurement is less than or equal to 10,000 Ω, reconnect the vehicle harness. Turn the ignition on. Then run steps listed in Table "Cruise Control Quick Check Table II, Check Out Brake and Clutch Switch and Wiring (Ignition ON Not Running)" ; and listed in Table "Cruise Control Quick Check Table III, Check Out Set/Coast and Resume/Accel Switches and Wiring (Ignition ON Not Running)" . If any DDR display received is not okay, refer to the indicated step. If all steps listed in Table "Cruise Control Quick Check Table II, Check Out Brake and Clutch Switch and Wiring (Ignition ON Not Running)" and listed in Table "Cruise Control Quick Check Table III, Check Out Set/Coast and Resume/Accel Switches and Wiring (Ignition ON Not Running)" , pass, then the cruise engage wire is shorted to the ground. Repair the short, or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is greater than 10,000 Ω, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.6
Check for Open at the Cruise Enable Circuit

Perform the following steps to check for an open circuit at the cruise enable circuit:‪

1. Turn ignition ON.
2. Disconnect the vehicle harness connector at the ECM.
3. Turn cruise enable switch to ON.
4. Measure resistance between the cruise enable cavity (i.e. F2) on the vehicle harness connector and a good ground.
   1. If the resistance measurement is greater than 5 Ω or open, the cruise engage switch is bad, circuit #953 is open or the cruise enable wire is open. Repair the open circuit or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is less than or equal to 5 Ω, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.7
Check for Open or Miswired Brake Switch

Perform the following steps to check for an open circuit or miswired brake switch:‪

1. Turn ignition OFF.
2. Disconnect the vehicle harness connector at the ECM.
3. Ensure the service brake is not engaged.
4. Measure resistance between the service brake cavity (i.e. G2) on the vehicle harness connector and a good ground.
   1. If the resistance measurement is greater than 5 Ω or open, the brake switch is miswired or faulty, circuit #953 is open or the ground is bad. Repair the open circuit, rewire or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is less than or equal to 5 Ω, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.8
Check for Short at the Brake Switch or Circuit

Perform the following steps to check for a short at the brake switch or circuit:‪

1. Turn ignition OFF.
2. Disconnect the vehicle harness connector at the ECM.
3. Engage the service brake.
4. Measure resistance between the service brake cavity (i.e. G2) on the vehicle harness connector and a good ground.
   1. If the resistance measurement is less than or equal to 10,000 Ω, the brake switch is miswired or the service brake circuit is shorted to ground. Rewire, repair the short or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is greater than 10,000 Ω or open, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.9
Check for Open or Miswired Clutch Switch

Perform the following steps to check for an open circuit or miswired clutch switch:‪

1. Turn ignition OFF.
2. Disconnect the vehicle harness connector at the ECM.
3. Ensure the clutch is not engaged.
4. Measure resistance between the clutch cavity (i.e. J2) on the vehicle harness connector and a good ground.
   1. If the resistance measurement is greater than 5 Ω or open, the clutch switch is miswired or faulty, circuit #953 is open, or there is a bad battery ground. Rewire, repair the short or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is less than or equal to 5 Ω, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.10
Check for Short at the Clutch Service/Circuit

Perform the following steps to check for a short:‪

1. Turn ignition OFF.
2. Disconnect the vehicle harness connector at the ECM.
3. Engage the clutch.
4. Measure resistance between the clutch cavity (i.e. J2) on the vehicle harness connector and a good ground.
   1. If the resistance measurement is less than or equal to 100 Ω, the clutch switch is miswired or faulty, or the clutch circuit is shorted to ground. Rewire, repair the short or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is greater than 100 Ω or open, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.11
Check for Short at the Set/Coast Circuit

Perform the following steps to check for a short:‪

1. Turn ignition OFF.
2. Disconnect the vehicle harness connector at the ECM.
3. Measure resistance between the set/coast cavity (i.e. J1) and a good ground.
   1. If the resistance measurement is less than or equal to 100 Ω, the set/coast switch is shorted, or a short to ground exists in the set/coast circuit (i.e. #541). Repair the short or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is greater than 100 Ω, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.12
Check for Open at the Set/Coast Circuit

Perform the following steps to check for an open circuit:‪

1. Turn ignition OFF.
2. Disconnect the vehicle harness connector at the ECM.
3. Find a means to press and hold the set/coast switch.
4. Measure resistance between the set/coast cavity (i.e. J1) and a good ground.
   1. If the resistance measurement is greater than 5 Ω or open, the set/coast switch is open or miswired, circuit #953 is open, or there is a bad battery ground. Rewire, repair the short or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is less than or equal to 5 Ω, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.13
Check for Short at the Res/Accel Circuit

Perform the following steps to check for a short:‪

1. Turn ignition OFF.
2. Disconnect the vehicle harness connector at the ECM.
3. Measure resistance between the Res/Accel cavity (i.e. G3) and a good ground.
   1. If the resistance measurement is less than or equal to 100 Ω, the Res/Accel switch is shorted, or a short to ground exists in the Res/Accel circuit (i.e. #541). Repair the short or replace the switch. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is greater than 100 Ω, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.14
Check for Open at the Res/Accel Circuit

Perform the following steps to check for an open circuit:‪

1. Turn ignition OFF.
2. Disconnect the vehicle harness connector at the ECM.
3. Find a means to press and hold the Res/Accel switch.
4. Measure resistance between the Res/Accel cavity (i.e. G3) and a good ground.
   1. If the resistance measurement is greater than 5 Ω or open, the Res/Accel switch is open or miswired, circuit #953 is open or the battery ground is bad. Repair the short, replace the switch, or rewire. Refer to "10.7.16 Verify Repairs" .
   2. If the resistance measurement is less than or equal to 5 Ω, refer to "10.7.2 Check ECM Connectors" .

Section 10.7.15
Verify Problem Still Exists

Perform the following steps to verify the problem still exists:‪

1. If you were referred to this step, you have completed the switch checkout process without detecting a fault.
2. Take the vehicle for a road test and check the cruise control operation.
   1. If the cruise control operates correctly, the problem no longer exists. If any other problems exist, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .
   2. If the cruise control does not operate correctly, check the vehicle speed sensor. Refer to "54.1 Description of Flash Code 54" .

Section 10.7.16
Verify Repairs

Perform the following steps to verify repairs:‪

1. Turn ignition OFF.
2. Reconnect all connectors.
3. Road test the vehicle.
   1. If the cruise control operates correctly, troubleshooting is complete.
   2. If the cruise control does not operate correctly, all system diagnostics are complete. Review this section from the start to find the error. Refer to "10.7.1 Determine Type of Cruise Control System" .