6E–4
ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor 6E–337. . . . . . . . . . . . . . . . . . . . . . . . .
Linear Exhaust Gas Recirculation (EGR)
Control 6E–337. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mass Air Flow (MAF) Sensor 6E–337. . . . . . . . . . . .
Manifold Absolute Pressure (MAP) Sensor 6E–338
Powertrain Control Module (PCM) 6E–338. . . . . . .
PCM Function 6E–338. . . . . . . . . . . . . . . . . . . . . . . . .
PCM Components 6E–339. . . . . . . . . . . . . . . . . . . . .
PCM Voltage Description 6E–339. . . . . . . . . . . . . . .
PCM Input/Outputs 6E–339. . . . . . . . . . . . . . . . . . . .
PCM Service Precautions 6E–339. . . . . . . . . . . . . .
Reprogramming The PCM 6E–339. . . . . . . . . . . . . .
Throttle Position (TP) Sensor 6E–339. . . . . . . . . . .
Transmission Fluid Temperature (TFT)
Sensor 6E–340. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmission Range Switch 6E–340. . . . . . . . . . . . .
Vehicle Speed Sensor (VSS) 6E–340. . . . . . . . . . . .
Use of Circuit Testing Tools 6E–340. . . . . . . . . . . . .
Aftermarket Electrical and Vacuum
Equipment 6E–340. . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrostatic Discharge Damage 6E–341. . . . . . . . .
Upshift Lamp 6E–341. . . . . . . . . . . . . . . . . . . . . . . . .
General Description (Air Induction) 6E–341. . . . . . . .
Air Induction System 6E–341. . . . . . . . . . . . . . . . . . .
General Description (Fuel Metering) 6E–341. . . . . . .
Acceleration Mode 6E–341. . . . . . . . . . . . . . . . . . . . .
Accelerator Controls 6E–341. . . . . . . . . . . . . . . . . . .
Battery Voltage Correction Mode 6E–341. . . . . . . .
CMP Signal 6E–341. . . . . . . . . . . . . . . . . . . . . . . . . . .
Clear Flood Mode 6E–342. . . . . . . . . . . . . . . . . . . . .
Deceleration Mode 6E–342. . . . . . . . . . . . . . . . . . . .
Engine Speed/Vehicle Speed/Fuel
Disable Mode 6E–342. . . . . . . . . . . . . . . . . . . . . . . .
Fuel Cutoff Mode 6E–342. . . . . . . . . . . . . . . . . . . . . .
Fuel Injector 6E–342. . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Metering System Components 6E–342. . . . . . Fuel Metering System Purpose 6E–342. . . . . . . . . .
Fuel Pressure Regulator 6E–343. . . . . . . . . . . . . . . .
Fuel Pump Electrical Circuit 6E–343. . . . . . . . . . . . .
Fuel Rail 6E–343. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Idle Air Control (IAC) Valve 6E–343. . . . . . . . . . . . .
Run Mode 6E–344. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Mode 6E–344. . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Body Unit 6E–344. . . . . . . . . . . . . . . . . . . . .
General Description (Electronic Ignition
System) 6E–344. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft Position (CMP) Sensor 6E–344. . . . . . . .
Crankshaft Position (CKP) Sensor 6E–345. . . . . . .
Electronic Ignition 6E–345. . . . . . . . . . . . . . . . . . . . .
Ignition Coils 6E–345. . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control 6E–345. . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control PCM Output 6E–347. . . . . . . . . . . .
Knock Sensor (KS) PCM Input 6E–347
. . . . . . . . . .
Powertrain Control Module (PCM) 6E–347. . . . . . .
Spark Plug 6E–347. . . . . . . . . . . . . . . . . . . . . . . . . . . .
A/C Clutch Diagnosis 6E–349. . . . . . . . . . . . . . . . . . . .
A/C Clutch Circuit Operation 6E–349. . . . . . . . . . . .
A/C Clutch Circuit Purpose 6E–349. . . . . . . . . . . . .
A/C Request Signal 6E–349. . . . . . . . . . . . . . . . . . . .
General Description (Exhaust Gas
Recirculation (EGR) System) 6E–349. . . . . . . . . . . . .
EGR Purpose 6E–349. . . . . . . . . . . . . . . . . . . . . . . . .
Linear EGR Valve 6E–349. . . . . . . . . . . . . . . . . . . . .
Linear EGR Control 6E–349. . . . . . . . . . . . . . . . . . . .
Linear EGR Valve Operation and Results
of Incorrect Operation 6E–349. . . . . . . . . . . . . . . . .
EGR Pintle Position Sensor 6E–350. . . . . . . . . . . . .
General Description (Positive Crankcase
Ventilation (PCV) System) 6E–350. . . . . . . . . . . . . . .
Crankcase Ventilation System Purpose 6E–350. . .
Crankcase Ventilation System Operation 6E–350.
6E–17 ENGINE DRIVEABILITY AND EMISSIONS
PCM Pinouts
PCM Pinout Table, 32-Way Red Connector – Row “A”
TS23344
PINPIN FunctionWire ColorIGN ONENG RUNRefer To
A15 Volt Reference “A”RED5.0 V5.0 VAppropriate Sensor
A2Knock SensorYEL0.0 V DC
2mV AC0.0 V DC
18mV AC
(at idle)General Description and
Operation, Knock Sensor
A3Not Used————
A4Battery FeedWHTB+B+Chassis Electrical
A5Idle Air Control (IAC) “A”
HighBLUB+/0.8 VB+/0.8 VGeneral Description and
Operation, IAC
A6IAC “A” LowBLU/WHTB+/0.8 VB+/0.8 VGeneral Description and
Operation, IAC
A7IAC “B” LowBLU/BLKB+/0.8 VB+/0.8 VGeneral Description and
Operation, IAC
A8IAC “B” HighBLU/REDB+/0.8 VB+/0.8 VGeneral Description and
Operation, IAC
A9Automatic Transmission
Fluid (ATF) LampORN/BLUB+B+Automatic Transmission
(4L30E)
A10Winter LampPNK/GRNB+B+Automatic Transmission
(4L30E)
A11Power LampGRY/WHTB+B+Automatic Transmission
(4L30E)
A12Antilock Brake System
(ABS)GRYB+B+Antilock Brake System
A13Malfunction Indicator
(Check Engine or MIL)
LampBLU0.0 VB+Chassis Electrical
A14“Check Transmission”
Lamp Driver (AT)ORN/BLKB+B+Chassis Electrical
Up Shift Lamp Driver (MT)ORN/BLU
6E–42
ENGINE DRIVEABILITY AND EMISSIONS
Intermittent Malfunction Indicator Lamp
In the case of an “intermittent” fault, the MIL (“Check
Engine” lamp) may illuminate and then (after three trips)
go “OFF”. However, the corresponding diagnostic trouble
code will be stored in the memory. When unexpected
diagnostic trouble codes appear, check for an intermittent
malfunction.
A diagnostic trouble code may reset. Consult the
“Diagnostic Aids” associated with the diagnostic trouble
code. A physical inspection of the applicable sub-system
most often will resolve the problem.
Data Link Connector (DLC)
The provision for communication with the control module
is the Data Link Connector (DLC). The DLC is used to
connect to Tech 2. Some common uses of Tech 2 are
listed below:
Identifying stored Diagnostic Trouble Codes (DTCs).
Clearing DTCs.
Performing output control tests.
Reading serial data.
TS24064
Verifying Vehicle Repair
Verification of vehicle repair will be more comprehensive
for vehicles with OBD system diagnostic. Following a
repair, the technician should perform the following steps:
1. Review and record the Fail Records and/or Freeze
Frame data for the DTC which has been diagnosed
(Freeze Frame data will only be stored for an A or B
type diagnostic and only if the MIL has been
requested).
2. Clear DTC(s).
3. Operate the vehicle within conditions noted in the Fail
Records and/or Freeze Frame data.
4. Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.
Following these steps are very important in verifying
repairs on OBD systems. Failure to follow these steps
could result in unnecessary repairs.
Reading Diagnostic Trouble Codes Using
A Tech 2
The procedure for reading diagnostic trouble code(s) is to
used a diagnostic Tech 2. When reading DTC(s), follow
instructions supplied by Tech 2 manufacturer.
Clearing Diagnostic Trouble Codes
IMPORTANT:Do not clear DTCs unless directed to do
so by the service information provided for each diagnostic
procedure. When DTCs are cleared, the Freeze Frame
and Failure Record data which may help diagnose an
intermittent fault will also be erased from memory.
If the fault that caused the DTC to be stored into memory
has been corrected, the Diagnostic Executive will begin to
count the “warm-up” cycles with no further faults
detected, the DTC will automatically be cleared from the
PCM memory.
To clear Diagnostic Trouble Codes (DTCs), use the
diagnostic Tech 2 “clear DTCs”. When clearing DTCs
follow instructions supplied by the tool manufacturer.
When Tech 2 is not available, DTCs can also be cleared
by disconnecting
one of the following sources for at least
thirty (30) seconds.
NOTE: To prevent system damage, the ignition key must
be “OFF” when disconnecting or reconnecting battery
power.
The power source to the control module. Examples:
fuse, pigtail at battery PCM connectors etc.
The negative battery cable. (Disconnecting the
negative battery cable will result in the loss of other
on-board memory data, such as preset radio tuning).
6E–58
ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
StepNo Ye s Va l u e ( s ) Action
341. Remove the A/C compressor relay.
2. Ignition “ON.”
3. Use a DVM to check voltage at both of the BRN
wires at the A/C compressor relay socket.
Is the voltage equal to the specified value?
+BGo to Step 36Go to Step 35
35Repair the faulty BRN wire between the A/C fuse and
the A/C compressor relay .
Is the action complete?
—Verify repair—
361. A/C compressor relay removed.
2. Engine idling.
3. A/C “ON.”
4. Blower “ON.”
5. Use a DVM to measure voltage between the
GRN/BLK wire at the A/C compressor relay socket
and battery
.
Did the DVM indicate the specified value?
+BGo to Step 40Go to Step 37
37Check for an open GRN/BLK wire between PCM
terminal B-14 and the A/C compressor relay.
Was the wire open?
—Go to Step 38Go to Step 39
38Repair the open GRN/BLK wire between the PCM and
the A/C compressor relay.
Is the action complete?
—Verify repair—
39Check for a damaged pin or terminal at B-14 of the
PCM.
Was a damaged pin or a terminal found?
—Go to Step 32Go to Step 33
401. A/C compressor relay removed.
2. Connect a fused jumper at the A/C compressor
relay socket between either BRN wire and the
BRN/YEL wire.
3. Engine idling.
4. A/C “ON.”
5. Blower “ON.”
Did the compressor magnetic clutch engage?
—Go to Step 41Go to Step 42
41Repair the A/C compressor relay.
Is the action complete?
—Verify repair—
42Check for an open circuit between the A/C compressor
relay and the A/C clutch.
Was an open circuit found?
—Go to Step 43Go to Step 44
43Repair the open circuit between the compressor Clutch
and the A/C compressor relay.
Is the action complete?
—Verify repair—
44Service the compressor clutch or replace the
compressor due to a faulty internal overheat switch.
Is the action complete?
—Verify repair—
6E–65 ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor Diagnosis
The Tech 2 has two data displays available for diagnosing
the knock sensor (KS) system. The two displays are
described as follows:
“Knock Retard” indicates the number of degrees that
the spark timing is being retarded due to a knock
condition.
“KS Noise Channel” indicates the current voltage level
being monitored on the noise channel.
DTCs P0325 and P0327 are designed to diagnose the KS
module, the knock sensor, and the related wiring. The
problems encountered with the KS system should set a
DTC. However, if no DTC was set but the KS system is
suspect because of a detonation complaint, refer to
Detonation/Spark Knock in Symptoms.
Powertrain Control Module (PCM)
Diagnosis
To read and clear diagnostic trouble codes, use a Tech 2.
IMPORTANT:Use of a Tech 2 is recommended to clear
diagnostic trouble codes from the PCM memory.
Diagnostic trouble codes can also be cleared by turning
the ignition “OFF” and disconnecting the battery power
from the PCM for 30 seconds. Turning off the ignition and
disconnecting the battery power from the PCM will cause
all diagnostic information in the PCM memory to be
cleared. Therefore, all the diagnostic tests will have to be
re-run.
Since the PCM can have a failure which may affect only
one circuit, following the diagnostic procedures in this
section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the PCM connections
or the PCM is the cause of a problem, and the PCM is
replaced, but this does not correct the problem, one of the
following may be the reason:
There is a problem with the PCM terminal connections.
The terminals may have to be removed from the
connector in order to check them properly.
The problem is intermittent. This means that the
problem is not present at the time the system is being
checked. In this case, refer to the
Symptoms p o r t i o n o f
the manual and make a careful physical inspection of
all component and wiring associated with the affected
system.
There is a shorted solenoid, relay coil, or harness.
S o l e n o i d s a n d r e l a y s a r e t u r n e d “ O N ” a n d “ O F F ” b y t h e
PCM using internal electronic switches called drivers.
A shorted solenoid, relay coil, or harness will not
damage the PCM but will cause the solenoid or relay to
be inoperative.
Multiple PCM Information Sensor
DTCS Set
Circuit Description
The powertrain control module (PCM) monitors various
sensors to determine the engine operating conditions.
The PCM controls fuel delivery, spark advance,
transmission operation, and emission control device
operation based on the sensor inputs.The PCM provides a sensor ground to all of the sensors.
The PCM applies 5 volts through a pull-up resistor, and
determines the status of the following sensors by
monitoring the voltage present between the 5-volt supply
and the resistor:
The engine coolant temperature (ETC) sensor
The intake air temperature (IAT) sensor
The transmission fluid temperature (TFT) sensor
The PCM provides the following sensors with a 5-volt
reference and a sensor ground signal:
The exhaust gas recirculating (EGR) pintle position
sensor
The throttle position (TP) sensor
The manifold absolute pressure (MAP) sensor
The PCM monitors the separate feedback signals from
these sensors in order to determine their operating
status.
Diagnostic Aids
IMPORTANT:Be sure to inspect PCM and engine
grounds for being secure and clean.
A short to voltage in one of the sensor input circuits may
cause one or more of the following DTCs to be set:
P0108
P0113
P0118
P0123
P0560
P0712
P0406
IMPORTANT:If a sensor input circuit has been shorted
to voltage, ensure that the sensor is not damaged. A
damaged sensor will continue to indicate a high or low
voltage after the affected circuit has been repaired. If the
sensor has been damaged, replace it.
An open in the sensor ground circuit between the PCM
and the splice will cause one or more of the following
DTCs to be set:
P0108
P0113
P0118
P0123
P0712
P0406
A short to ground in the 5-volt reference A or B circuit will
cause one or more of the following DTCs to be set:
P0107
P0122
In the 5-volt reference circuit A, between the PCM and the
splice, will cause one or more of the following DTCs to be
set:
P0122
In the 5-volt reference circuit B, between the PCM and the
splice, will cause one or more of the following DTCs to be
set:
P0107
Check for the following conditions:
6E–74
ENGINE DRIVEABILITY AND EMISSIONS
No Malfunction Indicator Lamp (MIL)
D06RW00006
Circuit Description
The “Check Engine” lamp (MIL) should always be
illuminated and steady with the ignition “ON” and the
engine stopped. Ignition feed voltage is supplied to the
MIL bulb through the meter fuse. The powertrain control
module (PCM) turns the MIL “ON” by grounding the MIL
driver circuit.
Diagnostic Aids
An intermittent MIL may be cased by a poor connection,
rubbed-through wire insulation, or a wire broken inside
the insulation. Check for the following items:
Inspect the PCM harness and connections for
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.
If the engine runs OK, check for a faulty light bulb, an
open in the MIL driver circuit, or an open in the
instrument cluster ignition feed.
If the engine cranks but will not run, check for an open
PCM ignition or battery feed, or a poor PCM to engine
ground.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. A “No MIL” condition accompanied by a no-start
condition suggests a faulty PCM ignition feed or
battery feed circuit.
9. Using a test light connected to B+, probe each of the
PCM ground terminals to ensure that a good ground
is present. Refer to
PCM Terminal End View for
terminal locations of the PCM ground circuits.
12.In this step, temporarily substitute a known good
relay for the PCM relay. The horn relay is nearby,
and it can be verified as “good” simply by honking
the horn. Replace the horn relay after completing
this step.
6E–75 ENGINE DRIVEABILITY AND EMISSIONS
17.This vehicle is equipped with a PCM which utilizes
an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed. Refer to
UBS
98 model year Immobilizer Workshop Manual.
No Malfunction Indicator Lamp (MIL)
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
2Attempt to start the engine.
Does the engine start?
—Go to Step 3Go to Step 6
3Check the meter fuse for the instrument cluster ignition
feed circuit.
Is the fuse OK?
—Go to Step 4Go to Step 16
4Ignition “ON,” probe the ignition feed circuit at the
cluster connector with a test light to ground.
Is the test light “ON?”
—Go to Step 5Go to Step 13
51. Ignition “OFF.”
2. Disconnect the PCM.
3. Jumper the MIL driver circuit at the PCM connector
to ground.
4. Ignition “ON.”
Is the MIL “ON?”
—Go to Step 10Go to Step 11
6Check the PCM ignition feed and battery feed fuses (15
A engine fuse and 15 A PCM fuse).
Are both fuses OK?
—Go to Step 7Go to Step 15
71. Ignition “OFF.”
2. Disconnect the PCM.
3. Ignition “ON.”
4. Probe the ignition feed circuit at the PCM harness
connector with a test light to ground.
Is the test light “ON?”
—Go to Step 8Go to Step 12
8Probe the battery feed circuit at the PCM harness
connector with a test light to ground.
Is the test light “ON?”
—Go to Step 9Go to Step 14
9Check for a faulty PCM ground connection.
Was a problem found?
—Verify repairGo to Step 10
10Check for damaged terminals at the PCM.
Was a problem found?
—Verify repairGo to Step 17
11Check for an open MIL driver circuit between the PCM
and the MIL.
Was a problem found?
—Verify repairGo to Step 18
12Substitute a known “good” relay for the PCM main
relay.
Was the malfunction fixed?
—Verify repairGo to Step 13
13Repair the open in the ignition feed circuit.
Is the action complete?
—Verify repair—
6E–76
ENGINE DRIVEABILITY AND EMISSIONS
No Malfunction Indicator Lamp (MIL)
StepNo Ye s Va l u e ( s ) Action
14Locate and repair the open PCM battery feed circuit.
Is the action complete?
—Verify repair—
15Locate and repair the short to ground in the PCM
ignition feed circuit or PCM battery feed circuit.
Is the action complete?
—Verify repair—
16Locate and repair the short to ground in the ignition
feed circuit to the instrument cluster, and replace the
fuse.
Is the action complete?
—Verify repair—
17Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
PCM in ON-Vehicle Service for
procedures.
Is the action complete?
—Verify repair—
18Check the MIL driver circuit for a poor connection at the
instrument panel connector.
Was a problem found?
—Verify repair
Go to
Instrument
Panel
in
Electrical
Diagnosis