Page 1353 of 6000

6E–236
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0502 – VSS Circuit Low Input
StepNo Ye s Va l u e ( s ) Action
101. Ignition “OFF.”
2. Disconnect the MAF sensor and remove the air
cleaner assembly and filter element to gain access
to the 16-way black connector located immediately
to the rear of the left front headlamp. The connector
attaches the VSS wires from the transmission
harness to the left-side engine harness.
3. Disconnect the black 16-way connector.
4. Select a terminal adapter from kit J 35616 that can
be used with a jumper to supply B+ to the blue wire
with a yellow tracer (transmission side of the
connector).
5. Use another terminal adapter to attach a voltmeter
to the light-green wire with a w h i l e t r a c e r ( n e x t t o t h e
wire in the previous step.)
6. Disconnect the blue connector next to the black
16-way connector, and locate the black/red tracer
wire at one corner of the blue connector. The
black/red wire is the VSS ground. Use a terminal
adapter to attach a jumper to ground to the
black/red VSS ground wire at the transmission side
of the blue connector.
7. Raise the rear wheels off the ground with
transmission in neutral.
Does the DVM toggle back and forth between 0.6 V and
10 V as the wheels (and driveshaft) are rotated?
—Go to Step 11Go to Step 12
11Replace the VSS.
Is the action complete?
—Verify repair—
12Check for an open or short between the PCM and the
speedometer.
Was a problem found?
—Verify repairGo to Step 13
13Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
Page 1354 of 6000

6E–237 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0562 System Voltage Low
D06RW020
Circuit Description
The powertrain control module (PCM) monitors the
system voltage on the ignition feed terminal to the PCM.
A system voltage DTC will set whenever the voltage is
below a calibrated value.
Conditions for Setting the DTC
Ignition “ON.”
System voltage is below 11.5 volts for 15 minutes.
Action Taken When the DTC Sets
The PCM will not illuminate the malfunction indicator
lamp (MIL).
The PCM will store as Failure Records conditions
which were present when the DTC was set. This
information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC
A history DTC P0562 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
DTC P0562 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
If the DTC sets when an accessory is operated, check for
a poor connection or excessive current draw.
Page 1355 of 6000

6E–238
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0562 – System Voltage Low
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
2Using a Tech 2, measure the battery voltage at the
battery.
Is the battery voltage greater than the specified value?
11.5 VGo to Step 3
Charge
battery, then
go to
Step 3
31. Using a Tech 2.
2. Select “Ignition Volts” on the Tech 2.
3. Start the engine and raise the engine speed to the
specified value.
4. Load the electrical system by turning on the
headlights, high blower, etc.
Is the ignition voltage approximately equal to the
specified value?
2000 RPM
12.8-14.1 V
Go to Step 4
Go to
Starting/Char
ging
41. Ignition “OFF.”
2. Disconnect the PCM connector at the PCM.
3. Using a DVM, measure the battery voltage at the
PCM connector A-4.
Is it approximately equal to battery voltage?
—
Check for
excessive
current draw
with ignition
“OFF,” engine
“OFF.”
Go to Step 5
51. Check for faulty connections at the PCM harness
terminals.
2. Repair as necessary.
Was a repair necessary?
—Verify repairGo to Step 6
6Check for an open battery feed circuit to the PCM.
Is the action complete?
—Verify repairGo to Step 7
7Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
Page 1356 of 6000

6E–239 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0563 System Voltage High
Circuit Description
The powertrain control module (PCM) monitors the
system voltage on the ignition feed terminals to the PCM.
A system voltage DTC will set whenever the voltage is
above a calibrated value.
Conditions for Setting the DTC
Ignition “ON.”
System voltage is above 16 volts for 15 minutes.
Action Taken When the DTC Sets
The PCM will not illuminate the malfunction indicator
lamp (MIL).
The PCM will store as Failure Records only conditions
which were present when the DTC was set. This
information will not be stored as Freeze Frame data.
Conditions for Clearing the MIL/DTC
A history DTC P0563 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
DTC P0563 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
If the DTC sets when an accessory is operated, check for
a poor connection or excessive current draw.
DTC P0563 – System Voltage High
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
2Using a Tech 2, measure the battery voltage at the
battery.
Is the battery voltage less than the specified value?
11 . 5 VGo to Step 3Go to Step 4
31. Charge the battery and clean the battery terminals.
2. Clean the battery ground cable connection if
corrosion is indicated.
Is the battery voltage less than the specified value?
11 . 5 V
Replace
battery
Go to Step 4
41. Turn “OFF” all the accessories.
2. Install a Tech 2.
3. Select the ignition voltage parameter on the Tech 2.
4. Start the engine and raise the engine RPM to the
specified value.
Is the voltage more than 2.5 volts greater than the
measurement taken in step 2 or 3?
2000 RPM
Go to
Starting/Char
ging
Go to Step 5
5Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98 model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
Page 1357 of 6000

6E–240
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0601 PCM Memory
Circuit Description
The powertrain control module (PCM) used in this vehicle
utilizes an electrically erasable programmable read-only
memory (EEPROM). The EEPROM contains program
information and the calibrations required for engine,
transmission, and powertrain diagnostics operation.
Unlike the PROM used in past applications, the EEPROM
is not replaceable.
Conditions for Setting the DTC
The PCM detects an internal program fault (check sum
error).
Action Taken When the DTC Sets
The PCM will not illuminate the malfunction indicator
lamp (MIL).
The PCM will store conditions which were present
when the DTC was set in the Failure Records data only.
Conditions for Clearing the MIL/DTC
DTC P0601 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
DTC P0601 indicates that the contents of the
EEPROM have changed since the PCM was
programmed. The only possible repair is PCM
replacement.
DTC P0601 – PCM Memory
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
2Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
Page 1358 of 6000

6E–241 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1154 HO2S Circuit Transition Time Ratio
Bank 2 Sensor 1
060RW190
Circuit Description
The powertrain control module (PCM) monitors the
heated oxygen sensor (HO2S) activity for 90 seconds
after “closed loop” and stoichiometric operation have
been enabled. During the monitor period the PCM counts
the number of times that the HO2S responds from
rich-to-lean and from lean-to-rich and adds the amount of
time it took to complete all transitions. With this
information, an average time for all transitions can be
determined. The PCM then divides the rich-to-lean
average by the lean-to-rich average to obtain a ratio. If
the HO2S transition time ratio is not within this range,
DTC P1154 will be set, indicating that the oxygen sensor
is not responding as expected to changes in exhaust
oxygen content.
Conditions for Setting the DTC
No related DTCs.
Engine coolant temperature (ETC) is above 50C
(122F) for automatic transmission; 75C (167F) for
manual transmission.
The engine is operating in “closed loop.”
The engine has been running at least one minute.
Canister purge duty cycle is greater than 2%.
Engine speed is between 1500 RPM and 3000 RPM.
Mass air flow is between 9 g/second and 42 g/second.
Above conditions are present for a 3-second
monitoring period.
90 seconds after “closed loop” and stoichiometric
operation have been enabled, Bank 2 HO2S 1
transition ratio between lean to rich and rich to lean is
less than 0.44 or greater than 3.8.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
”Open loop” fuel control will be in effect.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
DTC P1154 can be cleared by using Tech 2 “Clear Info”
function or by disconnecting the PCM battery feed.
Diagnostic Aids
A multifunction in the HO2S heater ignition feed or ground
circuit may cause a DTC P1154 to set. Check HO2S
heater circuitry for intermittent faults or poor connections.
If connections and wiring are OK and DTC P1154
continues to set, replace the Bank 2 HO2S 1.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
Page 1359 of 6000

6E–242
ENGINE DRIVEABILITY AND EMISSIONS
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. A condition that affects other heated oxygen sensors
indicates probable contamination. To avoid
damaging replacement sensors, correct the
condition which caused the contamination before
replacing the affected sensors.5. This step checks for conditions which may cause the
heated oxygen sensor to appear faulty. Correct any
of the described conditions if present.
8. To avoid damaging replacement sensors, correct the
condition which caused the contamination before
replacing the affected sensors.
DTC P1154 – HO2S Transition Time Ratio Bank 2 Sensor 1
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
2IMPORTANT:If any other DTCs are set (except P1133
and/or P1134), refer to those DTCs before proceeding
with this diagnostic chart.
1. Idle the engine at operating temperature.
2. Operate the vehicle within parameters specified
under “Conditions for Setting the DTC” criteria
included in Diagnostic Support.
3. Using a Tech 2, monitor “Specific DTC” info for DTC
P1154 until the DTC P1154 test runs.
Note the test result.
Does Tech 2 indicate DTC failed this ignition?
—Go to Step 3
Refer to
Diagnostic
Aids
3Did Tech 2 also indicate P1133, and/or P1134 test
failed?
—Go to Step 17Go to Step 4
4Check for leaks at the pipe joints.
Are the joints leaking?
—Go to Step 5Go to Step 6
5Tighten the U-bolt nuts at the leaking joints.
Is your action complete?
—Go to Step 2—
6Check for gaskets that are damaged or improperly
installed.
Are there damaged or misaligned gaskets?
—Go to Step 7Go to Step 8
71. Replace the damaged gaskets.
2. Align the connections.
3. Tighten the connections.
Is your action complete?
—Go to Step 2—
8Check for loose exhaust flange connections.
Are the flange connections loose?
—Go to Step 9Go to Step 10
9Tighten the stud nuts or bolts to specifications.
Is your action complete?
—Go to Step 2—
10Check for burned or corroded exhaust pipes.
Are the exhaust pipes burned or corroded?
—Go to Step 11Go to Step 12
11Replace the exhaust pipes, as required.
Is your action complete?
—Go to Step 2—
Page 1360 of 6000

6E–243 ENGINE DRIVEABILITY AND EMISSIONS
DTC P1154 – HO2S Transition Time Ratio Bank 2 Sensor 1
StepNo Ye s Va l u e ( s ) Action
12Check for leaks at the exhaust manifold.
Are there leaks at the exhaust manifold?
—Go to Step 13Go to Step 14
13Tighten the bolts to specifications or replace the
manifold if necessary.
Is your action complete?
—Go to Step 2—
14Visually/physically inspect the following items:
Ensure that the Bank 2 HO2S 1 is securely
installed.
Check for corrosion on terminals.
Check terminal tension (at Bank 2 HO2S 1 and at
the PCM).
Check for damaged wiring.
Was a problem found in any of the above areas?
—Go to Step 18Go to Step 15
151. Disconnect Bank 1 HO2S 1.
2. Ignition “ON.”
3. Using a DVM at the PCM side of the HO2S 1
connector, measure the voltage between the high
signal circuit and ground.
Also measure the voltage between the low signal
circuit and ground.
Are both voltages in the specified range?
3-4 V
Go to Step
16
Go to Step 19
161. With Bank 1 HO2S 1 disconnected, jumper the high
and low (PCM side) signal circuits to ground.
2. Ignition “ON.”
3. Using Tech 2, monitor the Bank 2 HO2S 1 voltage.
Does the scan too indicate less than 10 mV and
immediately return to about 450 mV when the jumper is
removed?
—Go to Step 21Go to Step 22
17Replace affected heated oxygen sensors.
NOTE: Before replacing sensors, the cause of the
contamination must be determined and corrected.
Fuel contamination.
Use of improper RTV sealant.
Engine oil/coolant consumption.
Is the action complete?
—Verify repair—
18Repair condition as necessary.
Is the action complete?
—Verify repair—
19Check for faulty PCM connections or terminal damage.
Is the action complete?
—Verify repairGo to Step 20
20Repair open, short or grounded signal circuit.
Is the action complete?
—Verify repair—