Signal Too Low

Signal too low

DTC status ECM-1400 Manifold absolute pressure (MAP) sensor. Signal too low

Reading of DTC status ECM-1400
Note! When reading off the DTC status, other stored diagnostic trouble codes (DTCs) and their status will be listed.

- Read off the DTC status. Check the status of the relevant Diagnostic Trouble Code (DTC).





Was the status of the relevant Diagnostic Trouble Code (DTC) displayed as permanent?

Yes - Checking connector

No - Intermittent fault

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Intermittent fault





Signal too low. Intermittent fault

Checking cables and connectors
Check reference voltage cable between control module connector #A58 (#A60) and manifold absolute pressure (MAP) sensor connector terminal 3 for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults or an intermittent short-circuit to ground according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.

Hint: With the ignition on and manifold absolute pressure (MAP) sensor connector disconnected the voltage between terminal 3 and ground terminal should be approximately 5V.

Check signal cable between control module connector #A23 (#A23) and manifold absolute pressure (MAP) sensor connector terminal 1 for an intermittent short-circuit to ground according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.

Hint: With the ignition on and manifold absolute pressure (MAP) sensor connector disconnected the voltage between terminal 1 and ground terminal should be approximately 5V.

Other information:
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box
- To access/replace the control module, see
- For information about signals, see Signal specification Signal Description / Specification
- To localize the manifold absolute pressure (MAP) sensor, see Location of components Locations.










Continue - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).

Do you want to view the information again?

Yes - Attempt New Test

No - Fault Found

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Attempt New Test - Checking cables and connectors

FAULT FOUND - DONE

DONE - DONE

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DONE - DONE

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Checking connector




- Ignition off.
- Check manifold absolute pressure (MAP) sensor connector for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.

Other information:
- For information about signals, see Signal specification Signal Description / Specification
- To localize the manifold absolute pressure (MAP) sensor, see Location of components Locations.






Continue - Checking manifold absolute pressure (MAP) sensor signal

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Checking manifold absolute pressure (MAP) sensor signal








- Ignition off.
- Reinstall components, reconnect connectors etc.
- Ignition on.
- Read off the manifold absolute pressure (MAP) sensor signal.
Check that the signal is within its permitted range. The manifold absolute pressure (MAP) sensor voltage is compared to the table value: Air pressure sensor intake manifold (MAP) Specifications.
If signal is now OK this indicates that the fault was caused by poor contact in the connector.

Other information:
- For information about signals, see Signal specification Signal Description / Specification
- To localize the manifold absolute pressure (MAP) sensor, see Location of components Locations.





Is the signal OK?

Yes - Verification

No - Checking wiring and components

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Checking wiring and components
Check reference voltage cable between control module connector #A58 (#A60) and manifold absolute pressure (MAP) sensor connector terminal 3 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault and a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Hint: With the ignition on and manifold absolute pressure (MAP) sensor connector disconnected the voltage between terminal 3 and ground terminal should be approximately 5V.

Check signal cable between control module connector #A23 (#A23) and manifold absolute pressure (MAP) sensor connector terminal 1 for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Hint: With the ignition on and manifold absolute pressure (MAP) sensor connector disconnected the voltage between terminal 1 and ground terminal should be approximately 5V.

If wiring is OK, try a new manifold absolute pressure (MAP) sensor.
Remedy as necessary.

Other information:
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box
- To access/replace the control module, see
- For information about signals, see Signal specification Signal Description / Specification
- To localize the manifold absolute pressure (MAP) sensor, see Location of components Locations.










Continue - Verification

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Verification




Verification

Verification

Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off.
- Reconnect connectors, reinstall components.
- Ignition on.
- Read off the manifold absolute pressure (MAP) sensor signal.
- Start the engine. Check that the signal varies (sinks) during acceleration.
Check that the signal is within its permitted range. The manifold absolute pressure (MAP) sensor voltage is compared to the table value: Air pressure sensor intake manifold (MAP) Specifications
Check that the signal is OK.





Is the signal OK?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFICATION FAILED - Fault-tracing information

VERIFIED - Fault Found

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - FAULT-TRACING FAILED

No - Attempt New Test

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FAULT-TRACING FAILED - FAULT-TRACING FAILED

Attempt New Test - DTC status ECM-1400 Manifold absolute pressure (MAP) sensor. Signal too low

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