Electronic: Diagnosis Ford Expedition I

DIAGNOSIS & TESTING

Note. For air suspension diagnostic and testing information not covered in this article, see 1998-99 ELECTRONIC -- EXPEDITION & NAVIGATOR 2000-01 ELECTRONIC -- EXPEDITION & NAVIGATOR in SUSPENSION.

VISUAL INSPECTION

Check the following mechanical items before proceeding with testing

1. Tire pressure, loose wheels.
2. Loose tie rod ends, inner ball joints.
3. Loose suspension struts or ball joints.
4. Loose universal joints.
5. Loose connecting bolts on column intermediate shaft.
6. Loose steering gear assembly.
7. Drive belt.
8. Binding or misaligned steering column.
9. Power steering pump, fluid level, hose leak or line restrictions.

Check the following electrical items before proceeding with testing

1. Open fuses: No. 109 (50-amp) located in battery junction box. No. 4 (15-amp) located in Central Junction Box (CJB). No. 6 (5-amp) located in CJB. No. 15 (5-amp) located in CJB. No. 20 (5-amp) located in CJB.
2. Open or short in circuitry or connections.
3. Electronic steering sensor.
4. Power steering pump actuator valve.
5. Output Shaft Speed Sensor (OSS).
6. EVO control module/air suspension module.
7. Diagnostic connector/data link connector.

If visual inspection reveals obvious problem(s) that can be readily identified, repair as necessary. If problem(s) remain after inspection, use Super STAR II tester (for EVO control module) or New Generation STAR (NGS) tester (for air suspension control module) to retrieve Diagnostic Trouble Codes (DTC). See MANUAL TEST (WITH EVO CONTROL MODULE) or PID TEST (WITH AIR SUSPENSION CONTROL MODULE) . If no DTCs are retrieved, go to SYMPTOM DIAGNOSIS .

PID TEST (WITH AIR SUSPENSION)

Note. PID test requires use of New Generation Star (NGS) Tester (418-F052). Follow manufacturer's instructions for proper operation.

1. Using NGS tester, monitor PIDs STEER_A, STEER_B, and VSS_AS (or VSS_ARC). Rotate the steering wheel 90 degrees left and right. If either STEER_A or STEER_B PID do not toggle between HIGH and LOW, go to «TEST F»(ref-96306-S29827780422001040700000) .
2. Take vehicle for short test drive. Drive at 35 MPH. While driving, compare the speedometer to the VSS_AS (or VSS_ARC) output on NGS tester. If the VSS_AS PID reads within 5 MPH of the speedometer, end PID Test. Go to «SYMPTOM DIAGNOSIS»(ref-96306-S17140994262001040700000) .
3. Repeat test drive while monitoring the Generic Electronic Module (GEM) PID VSS_GEM. If the VSS_GEM PID reads within 5 MPH of speedometer, repair circuit No. 679 (Gray/Black wire) between EVO module and air suspension module (both located behind center of instrument panel). If VSS_GEM PID reading is out of the above range, diagnose transfer case. See appropriate TRANSFER CASE article in TRANSFER CASES.

MANUAL TEST (WITHOUT AIR SUSPENSION)

Note. While the Super STAR II tester is in TEST mode, tester will cycle through the function test repeatedly.

1. Configure Super STAR II tester to FAST mode and EEC-IV/MCU. Turn tester on and place into HOLD mode. Connect Super STAR II tester to EVO diagnostic connector located below steering column. Turn ignition on. Place Super STAR II tester in TEST mode.
2. Run Function Test 21. Wait for the number 21 to be displayed; then place the tester in HOLD mode for 2 seconds and then back to TEST mode. If any diagnostic test codes are reported, record them for later use. Clear DTCs using Function Test 23. NOTE: Review the description of the function tests for test requirements to avoid misdiagnosis of the systems. See «FUNCTION TESTS (EVO CONTROL MODULE)»(ref-96306-S03201744062001040700000) .
3. Run each function test by placing tester in HOLD mode for 2 seconds and then back to TEST mode. Retrieve, record and clear all DTCs. Function Test 25, perform Actuator Test. Function Test 32, perform Electronic Steering Sensor Test. Function Test 34, perform Vehicle Speed Sensor Test.

Function Test 21

This function test will display all recorded DTCs. The last DTC shown is DTC 22, signifying that there are no more DTCs.

Function Test 23

This function test will clear all recorded DTCs. DTC 24 will be displayed to signify that all DTCs have been deleted.

Function Test 25 (Actuator Test)

This function test will test the electrical circuits for controlling the EVO actuator. DTC 26 signifies that the test passed without errors. DTCs 27-31 report what type of fault was found.

This function test will look for input from the electronic steering sensor. While the test is running, before it times out after 30 seconds, the steering wheel must be rotated 90 degrees. DTC 33 is reported if no input from the electronic steering sensor is seen.

Function Test 34 (Vehicle Speed Sensor Test)

This function test will look for input from the vehicle speed sensor (VSS). While the test is running, before it times out after 30 seconds, the module must see a speed greater than 15 MPH. DTC 35 is reported if no speed higher than 15 MPH is seen.

DIAGNOSTIC TROUBLE CODE INDEX (SUPER STAR II TESTER)

PUMP FLOW & PRESSURE TEST

Note. Ensure connection point will not interfere with any of the engine accessory drive components or drive belts.

1. Install power steering analyzer at high pressure port of power steering pump. Ensure power steering analyzer gate valve is fully open. Place dial thermometer in power steering pump reservoir. Check power steering fluid level. If necessary, add power steering fluid.
2. Install 88 Digital Multimeter. DO NOT hold steering wheel against stops for more than 3 to 5 seconds at a time. Damage to power steering pump will occur. Start engine. Place transmission in Neutral. Set parking brake. Raise power fluid steering temperature to 165-175°F (74-79°C). by rotating steering wheel fully to left and right several times.
3. Set engine speed to idle. Record flow rate and pressure readings. If flow rate is below idle flow rate specification, repair power steering pump. Continue with test procedure. If pressure reading is above idle pressure specification, check power steering hoses for kinks and restrictions.
4. Partially close gate valve to obtain 740 psi. Record flow rate. If flow rate is less than specification, install new power steering pump. DO NOT allow gate valve to remain closed for more than 5 seconds. Completely close and partially open gate valve 3 times. Record pressure relief valve actuation pressure reading. If pressure does not meet relief pressure specification, install new power steering pump.
5. Adjust engine speed to 1500 RPM. Record flow rate. If flow rate varies more than 1 gal. (3.785 L) per minute between initial flow rate reading, then install a new power steering pump.
6. Adjust engine speed at idle. Turn steering wheel to left and right stops. Record flow rate and pressure readings at stops. Flow rate should drop below 1/2 gal. (1.9 L) per minute. If pressure does not reach maximum pump relief pressure or flow rate does not drop below specified value, excessive internal leakage is occurring. Install new steering gear.
7. Turn steering wheel slightly in both directions and release quickly while watching pressure gauge. Pressure reading should move between normal back pressure reading and snap back as steering wheel is released. If pressure returns slowly or sticks, rotary valve in steering gear is sticking or steering column is binding. Check steering columns and linkages before repairing steering gear.

Unable To Enter Self-Test With Air Suspension

Possible source could be air suspension control module. Go to TEST C .

Unable To Enter Self-Test Without Air Suspension

Possible source could be EVO control module. Go to TEST D .

DIAGNOSTIC TESTS

Note. To identify terminals referenced in testing, see CONNECTOR IDENTIFICATION . To identify circuits and wire colors referenced in testing, see WIRING DIAGRAMS .

TEST A: NO COMMUNICATION WITH AIR SUSPENSION CONTROL MODULE

1. Ensure air suspension switch is in the ON position. If air suspension switch is on, go to next step. If air suspension switch is not on, turn air suspension switch on. Repeat self-test.
2. Turn ignition off. Disconnect air suspension control module connector. Turn ignition on. Measure voltage between air suspension control module connector terminal No. 1 (Dark Green/Yellow wire) and ground at harness side. see scheme 5 Measure voltage between air suspension control module connector terminal No. 21 (Dark Green/Yellow wire) and ground. see scheme 5 If voltages are greater than 10 volts, go to step 5. If only 1 circuit is greater than 10 volts, repair (Dark Green/Yellow wire), and repeat self-test. If both circuits are greater than 10 volts, go to next step.
3. Turn ignition off. Disconnect air suspension switch connectors. Turn ignition on. Measure voltage between air suspension switch connector terminal No. 1 (Violet/Orange wire) and ground. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair Violet/Orange wire. Repeat self-test.
4. Measure resistance between air suspension switch connector terminals No. 1 and No. 2 with air suspension switch ON and then OFF. If resistance is less than 5 ohms with air suspension switch at ON position and greater than 10,000 ohms with air suspension switch at OFF position, repair (Dark Green/Yellow wire), and repeat self-test. If resistance is not within specification, install NEW air suspension switch. Repeat self-test.
5. Turn ignition switch and air suspension switch off. Disconnect air suspension control module. Measure resistance between air suspension control module connector terminal No. 20 (Black/Pink wire) and ground at harness side. Measure resistance between air suspension control module connector terminal No. 32 (Black wire) and ground. see scheme 6 If resistance is less than 5 ohms, see appropriate MODULE COMMUNICATIONS NETWORK article in ACCESSORIES & EQUIPMENT. If resistance is more than 5 ohms, repair Black/Pink, Black/Light Blue and Black wires. Repeat self-test.

Scheme 3

Scheme 4

1. Turn ignition off. Disconnect EVO control module connectors. Turn ignition on. Measure voltage between EVO control module connector terminal No. 5 (Black wire) and ground. (Scheme 3) If voltage is not present, go to next step. If voltage is present, repair Black wire. Install NEW EVO control module. Repeat self-test.
2. Measure resistance between EVO control module connector terminal No. 5 (Black wire) and ground at harness side. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair Black wire, and repeat self-test.
3. Turn ignition on. Measure voltage between EVO control module connector terminal No. 7 (Light Blue/Pink wire) and ground at harness side. (Scheme 3) If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair Light Blue/Pink wire, and repeat self-test.
4. Measure resistance between EVO diagnostic connector terminal No. 2 (Orange/Black wire) and EVO control module connector terminal No. 4 (Orange/Black). Measure resistance between EVO diagnostic connector terminal No. 2 and ground. (Scheme 4). If resistance is less than 5 ohms between EVO diagnostic connector and control module, and greater than 10,000 ohms between EVO diagnostic connector and ground, go to next step. If resistance is not within specification, repair Orange/Black wire and repeat self-test.
5. Measure resistance between EVO diagnostic connector terminal No. 4 (Orange/Light Blue wire) and EVO control module connector terminal No. 3 (Orange/Light Blue wire) at harness side. Measure resistance between EVO diagnostic connector terminal No. 4 (Orange/Black wire) and ground at harness side. (Scheme 4) If resistance is less than 5 ohms between EVO diagnostic connector and EVO control module connector and greater than 10,000 ohms between EVO diagnostic connector and ground, go to next step. If resistance is not within specification, repair Orange/Black wire. Repeat self-test.
6. Measure resistance between EVO diagnostic connector terminal No. 5 (Light Green wire) and EVO control module connector terminal No. 2 (Light Green wire) at harness side. (Scheme 4) Measure resistance between EVO diagnostic connector terminal No. 4 (Light Green wire) and ground at harness side. If resistance is less than 5 ohms between EVO diagnostic connector and EVO control module connector and greater than 10,000 ohms between EVO diagnostic connector and ground, install new EVO control module. If resistance is not within specification, repair Light Green wire. Repeat self-test.

TEST C: UNABLE TO ENTER SELF-TEST (WITH AIR SUSPENSION)

Check communication to air suspension control module. If scan tool communicates with air suspension control module, install new air suspension control module. See appropriate ELECTRONIC article in SUSPENSION. Repeat self-test. If communication is not present, go to TEST A .

TEST D: UNABLE TO ENTER SELF-TEST (WITHOUT AIR SUSPENSION)

Check communication to EVO control module. If scan tool communicates with EVO control module, install new EVO control module. Repeat self-test. If communication is not present, go to TEST B .

1. Turn ignition off. Disconnect 2-pin EVO actuator connector. EVO actuator is located on power steering pump. Measure resistance between EVO actuator terminals. If resistance is 8-16 ohms, go to next step. If resistance is not 8-16 ohms, replace power steering pump. See «POWER STEERING PUMP»(ref-96306-S37109222322001040700000) under REMOVAL & INSTALLATION. Clear DTCs. Repeat self-test.
2. On models without air suspension, disconnect EVO control module harness connector C294. (Scheme 3)On models with air suspension, disconnect air suspension module harness connectors. Both modules are located behind center of instrument panel. Turn ignition on. Measure voltage between EVO actuator terminal No. 1 (Black/Orange wire) and ground at harness side. Measure voltage between EVO actuator connector terminal No. 2 (Red/Yellow wire) and ground at harness side. If voltage is present, repair Black/Orange wire and Red/Yellow wire. Clear DTCs and repeat self-test. If voltage is not present, go to next step.
3. Turn ignition off. Measure resistance between EVO actuator connector terminal No. 1 (Red/Yellow wire) and ground at harness side. Measure resistance between EVO actuator terminal No. 2 (Black/Orange wire) and ground at harness side. If resistances are greater than 10,000 ohms, go to next step. If resistances are less than 10,000 ohms, repair Black/Orange wire and Red/Yellow wire. Clear DTCs and repeat self-test.
4. On models without air suspension, check resistance between EVO actuator connector terminal No. 2 (Black/Orange wire) and EVO control module connector terminal No. 13 (Black/Orange wire). (Scheme 3) Measure resistance of Red/Yellow wire between EVO control module connector terminal No. 14 and EVO actuator harness connector terminal No. 1. On models with air suspension, check resistance between EVO actuator connector terminal No. 2 and air suspension control module connector terminal No. 27 (Black/Orange wire). Check resistance between EVO actuator connector terminal No. 1 (Red/Yellow wire) and air suspension control module connector terminal No. 26 (Red/Yellow wire). If resistance is less than 5 ohms in all tests, go to next step. If resistance is more than 5 ohms in either test, repair appropriate wire as necessary and retest system for normal operation.
5. Measure resistance between EVO actuator connector terminal No. 2 (Black/Orange wire) and terminal No. 1 (Red/Yellow wire) at harness side. If resistance is greater than 10,000 ohms, check connector pins. Clean and repair as necessary. Clear DTCs, and repeat self-test. If DTC35 repeats, replace EVO control module, or air suspension control module. Clear DTCs, and repeat self-test. If resistance is less than 10,000 ohms, repair Black/Orange wire and/or Red/Yellow wire. Clear DTCs and repeat self-test.

TEST F: DTC 33 - STEERING WHEEL ROTATION NOT DETECTED

1. Turn ignition off. If equipped with air suspension, disconnect air suspension control module C295. see scheme 5 If not equipped with air suspension, disconnect EVO control module connector. (Scheme 3) Turn ignition on. Place digital multimeter in diode check position. Ensure multimeter beeps several times while rotating steering wheel. Connect multimeter leads between air suspension control module C295 terminal No. 2 (Red wire) and ground at harness side. Listen for beep while turning steering wheel 1/4 turn in each direction. Connect digital multimeter leads between air suspension control module connector C295 terminal No. 6 (Brown wire) and ground. If multimeter beeps multiple times in both directions, install new EVO control module or air suspension control module. Clear DTCs and repeat self-test.
2. Turn ignition off. Disconnect steering wheel rotation sensor connector. Turn ignition on. Measure voltage between steering wheel rotation sensor connector terminals No. 1 (Gray/Yellow wire) and No. 4 (Black/Light Blue) at harness side. If voltage is greater than 10 volts, go to step 4. If voltage is less than 10 volts, go to next step.
3. Measure voltage between steering wheel rotation sensor connector terminal No. 1 (Gray/Yellow wire) and ground at harness side. If voltage is greater than 10 volts, repair Black/Light Blue wire. Clear DTCs, and repeat self-test. If voltage is less than 10 volts, repair Gray/Yellow wire. Clear DTCs, and repeat self-test.
4. Measure voltage between steering wheel sensor connector terminal No. 2 (Red wire) and ground at harness side. See «WIRING DIAGRAMS»(ref-96306-S04530872552001040700000). Measure voltage between steering wheel rotation sensor connector terminal No. 3 (Brown wire) and ground at harness side. If voltage is greater than 10 volts, repair Red wire and/or Brown wire. Clear DTCs, and repeat self-test. If voltage is less than 10 volts, go to next step.
5. Turn ignition off. Measure resistance between steering wheel rotation sensor terminal No. 2 (Red wire) and ground at harness side. Measure resistance between steering wheel rotation sensor terminal No. 3 (Brown wire) and ground at harness side. If resistances are greater than 10,000 ohms, go to next step. If resistances are less than 10,000 ohms, repair Red or Brown wire. Clear DTCs, and repeat self-test.
6. On vehicles without air suspension, check for resistance between steering wheel rotation sensor terminal No. 2 (Red wire) and EVO control module connector terminal No. 1 (Red wire). On vehicles with air suspension, check for resistance between steering wheel rotation sensor terminal No. 2 (Red wire) and air suspension control module connector terminal No. 2 (Red wire). On vehicles without air suspension, check for resistance between steering wheel rotation sensor terminal No. 3 (Brown wire) and EVO control module connector terminal No. 6 (Brown wire). On vehicles with air suspension, check for resistance between steering wheel rotation sensor terminal No. 3 (Brown wire) and air suspension control module connector terminal No. 22 (Brown wire). If resistances are less than 5 ohms, replace steering wheel rotation sensor. Clear DTCs, and repeat self-test. If resistances are more than 5 ohms, repair Red wire or Brown wire. Clear DTCs, and repeat self-test.

TEST G: STEERING DOES NOT VARY WITH VEHICLE SPEED

1. Test drive vehicle and observe speedometer. If speedometer operates properly, go to next step. If speedometer does not operate properly, repair speedometer as necessary.
2. Check power steering hydraulic system for leaks and proper operation. If no problem is found, go to next step. If problem is found, repair as necessary, and recheck hydraulic system for normal operation.
3. Turn ignition off. For vehicles with air suspension, disconnect air suspension control module connectors. see scheme 5and see scheme 6. If not equipped with air suspension, disconnect EVO control module connector. (Scheme 3) Measure resistance between air suspension control module connector terminal No. 20 (Black/Pink wire) or EVO control module connector terminal No. 8 (Pink/Orange wire) and ground at harness side. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair Black/Pink wire or Pink/Orange wire. Retest system for normal operation.
4. Disconnect Powertrain Control Module (PCM) 104-pin harness connector. PCM is located on right side of engine compartment. Connect EEC-V 104-pin breakout box to PCM. Measure resistance between air suspension control module connector terminal No. 3, or EVO control module connector terminal No. 9 (Gray/Black) and EEC-104 pin breakout box connector terminal No. 68 (Gray/Black wire). If resistance is less than 5 ohms, check air suspension control module or EVO control module connector for damage, and repair as necessary. If okay, replace air suspension control module or EVO control module. Retest system for normal operation. If resistance is more than 5 ohms, repair Gray/Black wire, and retest system for normal operation.

TEST H: STEERING VERY DIFFICULT/VERY EASY

1. Start engine and allow to idle. Rotate steering wheel left and right while observing power steering pump for leaks. Perform «PUMP FLOW & PRESSURE TEST»(ref-96306-S27106187122001040700000) . If no leaks exist and power steering flow and pressure are as specified, go to next step. If leaks exist and/or power steering flow and pressure are not as specified, replace/repair power steering pump as necessary. Retest system for normal operation.
2. Visually inspect steering linkage while an assistant rotates steering wheel from stop to stop. If steering linkage moves smoothly from stop to stop, go to next step. If steering linkage does not move smoothly from stop to stop, repair or replace linkage components as necessary. Retest for normal operation.
3. Turn ignition off. Check ball joints (2WD) or spindle pins (4WD) for lack of lubrication or worn surfaces. If steering pivot points are okay, go to next step. If problem is found, repair and/or ball joints or spindle pins as necessary. Retest for normal operation.
4. Visually inspect steering gear while an assistant rotates steering wheel from stop to stop. If steering gear mounting fasteners are loose, tighten or replace fasteners as necessary. Recheck system for normal operation. If steering gear fasteners are okay and condition still exists, go to «SYMPTOM DIAGNOSIS»(ref-96306-S17140994262001040700000) .

TEST I: STEERING DOES NOT VARY WITH INCREASED STEERING WHEEL ROTATION

Start engine and allow to idle. Rotate steering wheel left and right while observing power steering pump for leaks. Check power steering pump pressure and flow. See PUMP FLOW & PRESSURE TEST . If no leaks exist and power steering flow and pressure are as specified, inspect for kinked lines or hoses from power steering pump. Replace pipes or hose as necessary and recheck system for normal operation. If leaks exist and/or power steering flow and pressure are not as specified, replace/repair power steering pump as necessary and go to TEST H .