Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSVOLVO2004V70 L5-2.4L VIN 64 B5244S6REPAIR AND DIAGNOSISA L L DIAGNOSTIC TROUBLE CODES ( DTC )TESTING AND INSPECTIONMANUFACTURER CODE CHARTSECM CODES (ENGINE CONTROL MODULE)ECM-8400SIGNAL TOO HIGH
2004 Volvo V70 L5-2.4L VIN 64 B5244S6
Signal Too High
2004 Volvo V70 L5-2.4L VIN 64 B5244S6SECTION Signal Too High
Signal too high
Diagnostic trouble code (DTC) status ECM-8400 Power supply 5volt. Signal too high
Reading off diagnostic trouble code (DTC) status ECM-8400
Note! When reading off the diagnostic trouble code (DTC) status, other stored diagnostic trouble codes (DTCs) and their status will be listed.
- Read off the diagnostic trouble code (DTC) status. Check the status of the relevant diagnostic trouble code (DTC).
Was the status of the relevant diagnostic trouble code (DTC) permanent?
Yes - Checking the charge voltage
No - Intermittent fault
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Intermittent fault
Signal too high. Intermittent fault
Checking wiring
Check the cables between
- control module terminal #A57 and camshaft position (CMP) sensor terminal #1
- control module terminal #A58 and manifold absolute pressure (MAP) sensor terminal #3
- control module terminal #A58 and air conditioning (A/C) pressure sensor terminal #3
- control module terminal #B10 and fuel tank pressure sensor terminal #3.
Check for an intermittent short-circuit to supply voltage.
Other information
- To connect the breakout box and access the control module, see Connecting the breakout box Connecting the Breakout Box
- To access and replace the control module see Engine control module (ECM), replacing Service and Repair
- To access or replace the manifold absolute pressure (MAP) sensor, see Mass air flow (MAF) sensor, replacing Service and Repair
- To access or replace air conditioning (A/C) pressure sensor, see
- To access or replace the fuel tank pressure sensor, see Fuel tank pressure sensor, replacing Service and Repair
- For information about signals, see Signal specification Signal Description / Specification
- Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
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 wiring
FAULT FOUND - DONE
DONE - DONE
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DONE - DONE
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Checking the charge voltage
Note! The 5 volt supply for the various components is common internally in the control module. Therefore the control module cannot identify which of the outputs are short-circuited to supply voltage. Consequently all the affected outputs must be checked for a short-circuit to supply voltage.
Check the cables between
- control module terminal #A57 and camshaft position (CMP) sensor terminal #1
- control module terminal #A58 and manifold absolute pressure (MAP) sensor terminal #3
- control module terminal #A58 and air conditioning (A/C) pressure sensor terminal #3
- control module terminal #B10 and fuel tank pressure sensor terminal #3.
Check for a short-circuit to supply voltage.
Remedy as necessary.
Other information
- To connect the breakout box and access the control module, see Connecting the breakout box Connecting the Breakout Box
- To access or replace the control module, see Engine control module (ECM), replacing Service and Repair
- To access or replace the manifold absolute pressure (MAP) sensor, see Mass air flow (MAF) sensor, replacing Service and Repair
- To access or replace air conditioning (A/C) pressure sensor, see
- To access or replace the fuel tank pressure sensor, see Fuel tank pressure sensor, replacing Service and Repair
- For information about signals, see Signal specification Signal Description / Specification
- Checking wiring and terminals Checking Wiring And Terminals.
Continue - Verification
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Verification
Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off.
- Reinstall connectors, components etc.
- Ignition on.
Read off the 5 volt power supply to the sensors.
Is the voltage 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: Troubleshooting is complete for this DTC
NO: Repeat Procedure.
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RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.