6E–72
ENGINE DRIVEABILITY AND EMISSIONS
Te c h 2
ParameterRefer To Typical Data
Va l u e s
(2500 RPM) Typical Data
Values (IDLE) Units
Displayed Data List
HO2S Bank 2
Sen.1 (millivolts)O2 Sensor
DataMillivolts50-950 changing
quickly50-950 changing
quicklyGeneral Description and
Operation, Fuel Control
HO2S
HO2S Bank 1
Sen.1
(ready/not
ready)O2 Sensor
DataReady
Ye s / N oReady
Ye sReady
Ye sGeneral Description and
Operation, Fuel Control
HO2S; DTC: P0135
HO2S Bank 2
Sen.1
(ready/not
ready)O2 Sensor
DataReady
Ye s / N oReady
Ye sReady
Ye sGeneral Description and
Operation, Fuel Control
HO2S
HO2S Warm-Up
Time Bank 1
Sen.1O2 Sensor
DataSeconds25-4525-45General Description and
Operation, Fuel Control
HO2S
HO2S Warm-Up
Time Bank 2
Sen.1O2 Sensor
DataSeconds25-4525-45General Description and
Operation, Fuel Control
HO2S
IAT (Intake Air
Te m p )EngineDegrees C,
Degrees F0-100C,
depends on
underhood0-80C, depends
on underhoodGeneral Description and
Operation, Intake Air
Temperature (IAT) Sensor
Ignition VoltageEngineVo l t s12.8-14.112.8-14.1General Description and
Operation, Electronic
Ignition System
Inj. Pulse Bank
1EngineMillisecond
s2.0-4.02.5-4.0General Description, Fuel
Metering, Fuel Injector
Inj. Pulse Bank
2EngineMillisecond
s2.0-4.02.5-4.0General Description, Fuel
Metering, Fuel Injector
KS Noise
Channel (Knock
Sensor)EngineVo l t s0.10-0.400.50-1.75General Description and
Operation, Knock Sensor
Purpose and Operation;
DTCs: P0352, P0327
Loop StatusEngineOpen/Clos
edClosedClosedGeneral Description and
Operation, Fuel Metering
System; DTCs:
P0125-P0155
MAF (Mass Air
Flow)EngineGrams per
second2.85-6.659.5-16.5General Description and
Operation, MAF; DTCs:
P101, P0102, P0103
MAP kPa
(Manifold
Absolute
Pressure)EngineKilopascals
——
General Description and
Operation, Manifold
Absolute Pressure (MAP)
Sensor; DTCs: P0106,
P0107, P0108
MILEngineOn/OffOffOffOn-Board Diagnostic
System Check
Power
EnrichmentEngineInactive/Ac
tiveInactiveInactiveGeneral Description and
Operation, Acceleration
Mode
Spark
(Advance)EngineDegrees
Before Top
Dead
Center15-2234-44General Description and
Operation, Electronic
Ignition System
6E–73 ENGINE DRIVEABILITY AND EMISSIONS
Te c h 2
ParameterRefer To Typical Data
Va l u e s
(2500 RPM) Typical Data
Values (IDLE) Units
Displayed Data List
Start-Up ECT
(Engine Coolant
Te m p )EngineDegrees C,
Degrees FDepends on
engine coolant
temperature at
time of start-upDepends on
engine coolant
temperature at
time of start-upGeneral Description and
Operation, Engine Coolant
Temperature (ECT) Sensor
Start-Up IAT
(Intake Air
Te m p )EngineDegrees C,
Degrees FDepends on
intake air
temperature at
time of start-upDepends on
intake air
temperature at
time of start-upGeneral Description and
Operation, Intake Air
Temperature (IAT) Sensor
TP
(Throttle
Position)EnginePercent0
—
General Description and
Operation, Throttle
Position (TP) Sensor;
DTCs: P0121,
P0122,P0123
TP Sensor
(Throttle
Position)EngineVo l t s0.50-0.820.60-1.00General Description and
Operation, Throttle
Position (TP) Sensor;
DTCs: P0121,
P0122,P0123
Catalyst
Protection ModeEngineNo/YesNoNoGeneral Description, Fuel
Metering, catalytic
Converter Protection Mode
Vehicle SpeedEngineMPH /
km/h004L30-E Automatic
Transmission Diagnosis
EVAP Purge
SolenoidEnginePercent6599General Description
VIM SolenoidEngineOn/OffOnOnGeneral Description
Security Wait
TimeEngineActive/Inac
tiveInactiveInactive—
6E–80
ENGINE DRIVEABILITY AND EMISSIONS
Circuit Description
The electronic Ignition system uses a coil-at-plug method
of spark distribution. In this type of ignition system, the
powertrain control module (PCM) triggers the correct
driver inside the ignition coil, which then triggers the
correct ignition coil based on the 58X signal received from
the crankshaft position sensor (CKP). The spark plug
connected to the coil fires when the ICM opens the ground
circuit for the coil’s primary circuit.
During crank, the PCM monitors the CKP 58X signal. The
CKP signal is used to determine which cylinder will fire
first. After the CKP 58X signal has been processed by the
PCM, it will command all six injectors to allow a priming
shot of fuel for all the cylinders. After the priming, the
injectors are left “OFF” during the next six 58X reference
pulses from the CKP. This allows each cylinder a chance
to use the fuel from the priming shot. During this waiting
period, a camshaft position (CMP) signal pulse will have
been received by the PCM. The CMP signal allows the
PCM to operate the injectors sequentially based on
camshaft position. If the camshaft position signal is not
present at start-up, the PCM will begin sequential fuel
delivery with a 1-in-6 chance that fuel delivery is correct.
The engine will run without a CMP signal, but will set a
DTC code.
Diagnostic Aids
An intermittent problem may be caused by a poor
connection, rubbed-through wire insulation or a wire
broken inside the insulation. Check for the following
items:
Poor connection or damaged harness – Inspect the
PCM harness and connectors for improper mating,
broken locks, improperly formed or damaged
terminals, poor terminal-to-wire connection, and
damaged harness.
Faulty engine coolant temperature sensor – Using
Tech 2, compare engine coolant temperature with
intake air temperature on a completely cool engine.
Engine coolant temperature should be within 10
C of
intake air temperature. If not, replace the ECT sensor.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
5. An obvious cause of low fuel pressure would be an
empty fuel tank.
6. The engine will easily start and run if a few injectors
are disabled. It is not necessary to test all injectors
at this time since this step is only a test to verify that
all of the injectors have not been disabled by fuel
contamination.
7. A blinking test light verifies that the PCM is
monitoring the 58X crankshaft reference signal and
is capable of activating the injectors. If there is an
open or shorted driver circuit, DTCs 201-206 should
be set.
19.By using a spark tester, each ignition coil’s ability to
produce 25,000 volts is verified.
25.If there is an open or shorted driver circuit, DTCs
201-206 should be set. All six injector driver circuits
can be checked at one time without removing the
intake manifold if a 5-8840-2636-0 test light is
available. This is the alternative procedure:
With the ignition “OFF,” disconnect the gray
connector located at the rear of the air filter, attached
to a bracket on the purge canister.
Connect test light 5-8840-2636-0 to the connector.
Do any of the light constantly illuminate or fail to blink
when the engine is cranked? If so, repair the short or
open circuit, or replace the PCM if indicated.
This procedure only tests the driver circuit as far as the
test connection, so step 31 is added to test the circuit all
the way to the injector.
6E–81 ENGINE DRIVEABILITY AND EMISSIONS
Engine Cranks But Will Not Run
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
2Check the 15 A ignition coil fuse, the 15 A engine fuse,
and the 30 A PCM fuse.
Was a fuse blown?
—Go to Step 3Go to Step 4
3Check for a short to ground and replace the fuse.
Is the action complete?
—Verify repair—
41. Ignition “OFF,” install a fuel pressure gauge at the
test fitting on the fuel supply line in the engine
compartment. (Use a shop cloth to absorb any fuel
leakage while making the connection.)
2. Ignition “ON,” observe the fuel pressure.
Is the fuel pressure within the specified values, and
does it hold steady?
285-376 kPa
(43-55 psi)
Go to Step 6Go to Step 5
5Is any fuel pressure indicated?
—
Go to Fuel
System
Electrical TestGo to Fuel
System
Diagnosis
6Install an injector switch box to the injector test
connector, and attempt to operate the injector.
Did the fuel pressure drop when the injector is
operated?
—Go to Step 7Go to Step 12
7Install an injector test light at the #2 cylinder injector
harness connector.
Does the light blink when the engine is cranked?
—Go to Step 8Go to Step 18
81. Ignition “ON.”
2. While the coil connectors are disconnected, touch
each coil connector’s ignition feed terminal with a
grounded test light (the ignition feed wire is black
with orange tracer).
Did the test light illuminate?
—Go to Step 10Go to Step 9
9Repair the open ignition feed circuit.
Is the action complete?
—Verify repair—
10While the coil connectors are disconnected, touch
each connector’s secondary ground terminal with a
test light to B+. (The ground wires are black.)
Did the test light illuminate at each coil connector?
—Go to Step 12Go to Step 11
11Repair the open secondary ground circuit.
Is the action complete?
—Verify repair—
121. Test the fuel for contamination.
2. If a problem is found, clean the fuel system and
correct the contaminated fuel condition as
necessary. Replace the fuel filter and replace any
injectors that are not delivering fuel (see Injector
Balance Test).
Was a problem found?
—Verify repairGo to Step 13
6E–85 ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Electrical Test
D06RW101
Circuit Description
When the ignition switch is first turned “ON,” the
powertrain control module (PCM) energizes the fuel
pump relay which applies power to the in-tank fuel pump.
The fuel pump relay will remain “ON” as long as the
engine is running or cranking and the PCM is receiving
58X crankshaft position pulses. If no 58X crankshaft
position pulses are present, the PCM de-energizes the
fuel pump relay within 2 seconds after the ignition is
turned “ON” or the engine is stopped.
The fuel pump delivers fuel to the fuel rail and injectors,
then to the fuel pressure regulator. The fuel pressure
regulator controls fuel pressure by allowing excess fuel to
be returned to the fuel tank. With the engine stopped and
ignition “ON,” the fuel pump can be turned “ON” by using a
command by Tech 2.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed-through wire insulation, or a wire broken inside
the insulation. Check for the following items:
Poor connection or damaged harness – Inspect the
PCM harness and connectors for improper mating,
broken locks, improperly formed or damaged
terminals, poor terminal-to-wire connection, and
damaged harness.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. If the fuel pump is operating but incorrect pressure is
noted, the fuel pump wiring is OK and the “Fuel
System Pressure Test” chart should be used for
diagnosis.
6E–86
ENGINE DRIVEABILITY AND EMISSIONS
CAUTION: To reduce the risk of fire and personal
injury:
It is necessary to relieve fuel system pressure
before connecting a fuel pressure gauge. Refer to
Fuel Pressure Relief Procedure, below.
A small amount of fuel may be released when
disconnecting the fuel lines. Cover fuel line
fittings with a shop towel before disconnecting, to
catch any fuel that may leak out. Place the towel in
an approved container when the disconnect is
completed.
Fuel Pressure Relief Procedure
1. Remove the fuel cap.
2. Remove the fuel pump relay from the underhood
relay center.
3. Start the engine and allow it to stall.
4. Crank the engine for an additional 3 seconds.
Fuel Gauge Installation
1. Remove the shoulder fitting cap.
2. Install fuel gauge 5-8840-0378-0 to the fuel feed line
located in front of and above the right side valve train
cover .
3. Reinstall the fuel pump relay.
Fuel System Electrical Test
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Read the “Caution” above.
2. Relieve the fuel system pressure and install the fuel
pump pressure gauge to the test fitting.
3. Use Tech 2 to command the fuel pump “ON.”
Is there an immediate pressure build-up which
indicates the pump is running?
—Go to Step 3Go to Step 4
31. Verify that the pump is not running by removing the
fuel filler cap and listening.
2. Command the pump “ON” with Tech 2.
Did the pump turn “OFF” after 2 seconds?
—
Te s t
completed
Go to Step 12
41. Ignition “OFF.”
2. Remove the fuel pump relay.
3. Using a test light connected to ground, probe the
battery feed to the relay.
Did the light illuminate?
—Go to Step 6Go to Step 5
5Repair short or open battery feed to fuel pump relay.
Is the action complete?
—Verify repair—
61. Connect a test light between the two wires that
connect to the fuel pump relay pull-in coil.
2. Ignition “ON.”
Did the test light illuminate for 2 seconds and then turn
off?
—Go to Step 12Go to Step 7
71. With a test light connected to battery (–), probe the
fuel pump relay connector at the wire which runs
from the relay pull-in coil to the PCM.
2. Ignition “ON.”
Did the test light illuminate for 2 seconds and then turn
off?
—Go to Step 8Go to Step 9
8Locate and repair open in the fuel pump relay ground
circuit.
Is the action complete?
—Verify repair—
6E–87 ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Electrical Test
StepNo Ye s Va l u e ( s ) Action
9Check for short or open between the PCM and the fuel
pump relay.
Was a problem found?
—Verify repairGo to Step 10
101. Check the fuel pump relay circuit for a poor terminal
connection at the PCM.
2. If a problem is found, replace terminal as necessary.
Was a problem found?
—Verify repairGo to Step 11
11Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
121. Reconnect the fuel pump relay.
2. Disconnect the fuel pump electrical connector at the
fuel tank.
3. Using a test light connected to ground, probe the
fuel pump feed wire (harness side).
4. Command the fuel pump “ON” with Tech 2.
Did the light illuminate for 2 seconds?
—Go to Step 15Go to Step 13
131. Honk the horn to verify that the horn relay is
functioning.
2. Substitute the horn relay for the fuel pump relay.
3. Leave the test light connected as in step 12.
4. Command the fuel pump “ON” with Tech 2.
Did the test light illuminate for 2 seconds when the fuel
pump was commanded “ON?”
—Go to Step 17Go to Step 14
141. Re-connect the horn relay in its proper location.
2. Check for a short circuit, blown fuse or open circuit
between the relay and the fuel tank.
Is the action complete?
—Verify repair—
151. With the fuel pump electrical connector at the fuel
tank disconnected, connect a test light between the
feed wire and the ground wire (harness side).
2. Command the fuel pump “ON” with Tech 2.
Did the test light illuminate for 2 seconds?
—Go to Step 18Go to Step 16
16Repair the open circuit in the fuel pump ground wire.
Is the action complete?
—Verify repair—
171. Re-connect the horn relay in its proper location.
2. Replace the fuel pump relay.
Is the action complete?
—Verify repair—
18Replace the fuel pump.
Is the action complete?
—Verify repair—
6E–88
ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis
140RW020
Legend
(1) Fuel Filler Cap
(2) Fuel Tank
(3) Rollover Valve
(4) Fuel Pump and Sender Assembly
(5) Fuel Filter
(6) Fuel Rail Right
(7) Right Bank(8) Fuel Rail Left
(9) Left Bank
(10) Fuel Pressure Control Valve
(11) Common Chamber
(12) Duty Solenoid Valve
(13) Throttle Valve
(14) Canister
(15) Evapo Shut Off Valve
Circuit Description
When the ignition switch is turned “ON,” the powertrain
control module (PCM) will turn “ON” the in-tank fuel
pump. The in-tank fuel pump will remain “ON” as long as
the engine is cranking or running and the PCM is receiving
58X crankshaft position pulses. If there are no 58X
crankshaft position pulses, the PCM will turn the in-tank
fuel pump “OFF” 2 seconds after the ignition switch is
turned “ON” or 2 seconds after the engine stops running.
The in-tank fuel pump is an electric pump within an
integral reservoir. The in-tank fuel pump supplies fuel
through an in-line fuel filter to the fuel rail assembly. The
fuel pump is designed to provide fuel at a pressure above
the pressure needed by the fuel injectors. A fuel pressure
regulator, attached to the fuel rail, keeps the fuel available
to the fuel injectors at a regulated pressure. Unused fuel
is returned to the fuel tank by a separate fuel return line.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Connect the fuel pressure gauge to the fuel feed line
as shown in the fuel system illustration. Wrap a
shop towel around the fuel pressure connection in
order to absorb any fuel leakage that may occur
when installing the fuel pressure gauge. With the
ignition switch “ON” and the fuel pump running, the
fuel pressure indicated by the fuel pressure gauge
should be 333-376 kPa (48-55 psi). This pressure
is controlled by the amount of pressure the spring
inside the fuel pressure regulator can provide.
3. A fuel system that cannot maintain a constant fuel
pressure has a leak in one or more of the following
areas:
The fuel pump check valve.
The fuel pump flex line.