Part 1

Faulty signal

EFI-355 Mass air flow (MAF) sensor, faulty signal

Checking throttle position (TP) sensor

- Ignition on.

- Select Volvo Scan Tool (ST) to read off the value of the throttle position (TP) sensor signal while the throttle slowly opens from closed to wide open.

The signal should follow throttle position and should not have any interference.

OK - Checking for air leakage in the intake system

Not OK - Replacing component

-------------------------------------------------

Replacing component
- Try a new throttle position (TP) sensor.

Continue - Verification

-------------------------------------------------

Checking connector

- Ignition off.
- Check throttle position (TP) sensor and/or engine control module (ECM) connectors for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Connect throttle position (TP) sensor and/or the engine control module (ECM).
- Ignition on.

- Select Volvo Scan Tool (ST) to read off the value of the throttle position (TP) sensor.

At closed throttle position (CTP) voltage should be between 0.2 - 0.6 V. At wide open throttle (WOT) voltage should be between 3.8 - 4.6 V.

OK - Checking for contact resistance and oxidation

Not OK - Checking ground lead

-------------------------------------------------

Checking for contact resistance and oxidation
The cause of the diagnostic trouble code (DTC) has been loose connections in the throttle position (TP) sensor and/or the engine control module (ECM) connectors.

Continue - Verification

-------------------------------------------------

Checking ground lead

- Ignition off.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
- Disconnect throttle position (TP) sensor.

Note! If the engine cooling fan runs on, it must be allowed to stop before taking resistance readings.

Connect an ohmmeter between throttle position (TP) sensor connector terminal 1 and ground.

The ohmmeter should read approximately 0 ohms.

OK - Checking the signal cable

Not OK - Checking for a short-circuit

-------------------------------------------------

Checking for a short-circuit
Check cable between throttle position (TP) sensor terminal 1 and engine control module (ECM) #A18 for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Continue - Verification

-------------------------------------------------

Checking the signal cable

- Ignition on.
- Throttle position (TP) sensor disconnected.
Connect a voltmeter between throttle position (TP) sensor connector terminal 3 and ground.

The voltmeter should read approximately 5 V.

OK - Checking power cable

Not OK - Checking for a short-circuit

-------------------------------------------------

Checking for a short-circuit
Check cable between throttle position (TP) sensor terminal 3 and engine control module (ECM) #A16 for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Continue - Verification

-------------------------------------------------

Checking power cable

The ohmmeter should read approximately 0.4 - 0.8 kohms.

OK - Replacing component

Not OK - Checking for a short-circuit

-------------------------------------------------

Replacing component
- Try a new throttle position (TP) sensor.

Continue - Verification

-------------------------------------------------

Checking for a short-circuit
Check cable between throttle position (TP) sensor terminal 2 and engine control module (ECM) #A15 for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Continue - Verification

-------------------------------------------------

Checking for air leakage in the intake system
Check for air leakage in the intake system according to Check for air leaks in the intake system Air Leaks In the Intake System, Checking.

Is there a leak?

Yes - Fault-tracing information

No - Checking power ground

-------------------------------------------------

Fault-tracing information
Remedy as necessary.

Continue - Verification

-------------------------------------------------

Checking power ground

- Ignition off.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
- Disconnect mass air flow (MAF) sensor.
Connect an ohmmeter between mass air flow (MAF) sensor connector terminal 1 and ground.

The ohmmeter should read approximately 0 ohms.

OK - Checking signal ground

Not OK - Checking control module connector

-------------------------------------------------

Checking control module connector

- Ignition off.
- Mass air flow (MAF) sensor disconnected.
- Check control module connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Control module connected.

- Connect an ohmmeter between mass air flow (MAF) sensor connector terminal 1 and ground.

The ohmmeter should read approximately 0 ohms.

OK - Checking signal ground

Not OK - Checking for contact resistance and oxidation

-------------------------------------------------

Checking for contact resistance and oxidation

- Check cable between mass air flow (MAF) sensor terminal 1 and engine control module (ECM) #A3 for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Continue - Verification

-------------------------------------------------