Mazda MX-6 1998, Workshop Manual

Page: 48 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P0108 EGR boost sensor circuit input signal out of self-test range maximum
D E S C R IP TIO N
• Continuous memory DTC P0108 indicates EGR boost sensor signal circuit input is greater
than self-test maximum
[Possible Cause]
• Damaged EGR boost sensor • Damaged PCM
• Damaged EGR boost solenoid valve • Damaged harness connector
• Damaged EGR boost solenoid valve to EGR boost • Damaged harness
sensor hose
STEP
INSPECTION
ACTION
1 CHECK EGR BOOST SENSOR CONSTANT
VOLTAGE
• Key on, engine off.
• EGR boost sensor disconnected.
• Measure voltage between constant voltage
circuit and ground circuit at EGR boost
sensor vehicle harness connector.
• Is voltage between 4.0 and 6.0 volts?
Yes Go to next step.
No
REPAIR open in constant voltage circuit.
2
CHECK CONTINUITY OF EGR BOOST
SENSOR SIGNAL CIRCUIT
• Key off.
• EGR boost sensor disconnected.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion, loose wires,
etc. Service as necessary.
• Install breakout box. Leave PCM
disconnected.
• Measure resistance between ground circuit
at EGR boost sensor vehicle harness
connector and Test Pin 91 at breakout box.
• Is resistance less than 5 ohms?
Yes Go to next step.
No SERVICE open in EGR boost sensor signal circuit.
RESET PCM to completely clear DTCs.
st
After Repair Procedure
COMPLETE OBD II Drive Mode.
Confirm repair by performing EGR portion of OBD II Drive
Mode to check for DTCs.
3 CHECK EGR BOOST SENSOR SIGNAL
CIRCUIT FOR SHORT TO POWER
• Key off.
• EGR boost sensor disconnected.
• Breakout box installed. PCM disconnected.
• Measure resistance between Test Pin 34
and Test Pins 71, 97 and 90 at breakout
box.
• Is resistance greater than 10,000 ohms?
Yes Go to next step.
No
SERVICE short in EGR boost sensor signal circuit.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
st
After Repair Procedure
COMPLETE OBD II Drive Mode.
Confirm repair by performing EGR portion of OBD II Drive
Mode to check for DTCs.
4 CHECK RESPONSE OF EGR BOOST
SENSOR TO MANUALLY APPLIED SIGNAL
• Key off.
• Disconnect hose from
EGR
boost solenoid
to
EGR
boost sensor. Inspect for damage,
blockage, etc. Service as necessary.
• Breakout box installed. PCM connected.
• Key on.
• Using a hand held pump, slowly apply and
m aintain-7 1 k P a {-5 3 3 m m H g ,-21 inHg},
while measuring EGR boost sensor voltage
response at Test Pin 34 of breakout box.
• Is voltage response between 0.8 and 1.5
volts?
Yes REMOVE the vacuum pump.
RECONNECT all components.
Go to DTC P0106 Troubleshooting step 5.
No REPLACE EGR boost sensor.
REMOVE breakout box.
RECONNECT all components.
RESET PCM to completely clear DTCs.
s t
After Repair Procedure
COMPLETE OBD II Drive Mode.
Confirm repair by performing tG R portion of OBD II Drive
Mode to check for DTCs.
0 1 -0 1 A -2 0