Control Module Communication
Control module communication
Checking the status of the diagnostic trouble code (DTC)
- Start the engine and let it idle for approximately 60 seconds.
Read off diagnostic trouble codes (DTCs).
Is the status of diagnostic trouble codes (DTCs) AT-521, -522, -523, -524, -525, -526 or -527 intermittent?
Yes - Intermittent fault
No - Checking signal cables and terminals
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Checking signal cables and terminals
Check the cable between transmission control module (TCM) terminal #14 and engine control module (ECM) terminal #57. Check the cable between transmission control module (TCM) terminal #27 and engine control module (ECM) terminal #27 for:
- an open-circuit according to
Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
- a short-circuit to ground according to
Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
- and a short-circuit to supply voltage according to
Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
- a short-circuit to each other.
Remedy as necessary.
Were any faults found in the cables?
Yes - Verification
No - Checking the control module communication
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Checking the control module communication
- Start the engine and let it idle for approximately 60 seconds.
Read off diagnostic trouble codes (DTCs) again.
Is the status of diagnostic trouble codes (DTCs) AT-521, -522, -523, -524, -525, -526 or -527 now intermittent?
Yes - Contact resistance
No - Checking the Transmission Control Module (TCM)
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Contact resistance
The cause of the diagnostic trouble code (DTC) was loose connections in the control module connectors.
Check the connectors for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
Continue - Verification
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Checking the Transmission Control Module (TCM)
- Ignition off.
- Try a new transmission control module (TCM) according to Replacing the transmission control module (TCM) .
Note! Mark the old control module so that it cannot be mistaken for the new one.
- Ignition on.
Erase any diagnostic trouble codes (DTCs) stored in the new control module.
Continue - Read off the status of the diagnostic trouble code (DTC)
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Read off the status of the diagnostic trouble code (DTC)
- Start the engine and let it idle for approximately 60 seconds.
Read off diagnostic trouble codes (DTCs) again.
Is the status of diagnostic trouble codes (DTCs) AT-521, -522, -523, -524, -525, -526 or -527 now intermittent?
Yes - FAULT FOUND
No - Checking the engine control module (ECM)
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Checking the engine control module (ECM)
- Ignition off.
- Reinstall the old transmission control module (TCM).
- Try a new engine control module (ECM) according to Replacing the engine control module (ECM) Service and Repair. For model year 2000- according to Engine control module (ECM), replacing Service and Repair
Note! Mark the old control module so that it cannot be mistaken for the new one.
- Ignition on.
Erase any diagnostic trouble codes (DTCs) stored in the new engine control module (ECM).
Continue - Read off the status of the diagnostic trouble code (DTC) in the automatic transmission
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Read off the status of the diagnostic trouble code (DTC) in the automatic transmission
- Start the engine and let it idle for approximately 60 seconds.
Read off diagnostic trouble codes (DTCs).
Is the status of diagnostic trouble codes (DTCs) AT-521, -522, -523, -524, -525, -526 or -527 now intermittent?
Yes - FAULT FOUND
No - Replacing the transmission control module (TCM)
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Replacing the transmission control module (TCM)
Replace the old transmission control module (TCM) according to Replacing the transmission control module (TCM) .
Continue - Verification
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Verification
Verification
Hint: After carrying out the repair check that the fault has been remedied.
- Ignition off.
- Restore components and connectors.
- Start the engine. Allow the engine to idle for approximately 1 minute.
Read off diagnostic trouble codes (DTCs).
Any of the trouble codes AT-521, -522, -523, -524, -525, -526, or -527 intermittent status now?
Yes - VERIFIED
No - VERIFICATION FAILED
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VERIFIED - FAULT FOUND
VERIFICATION FAILED - Fault-tracing information
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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 - Exit fault-tracing
No - Attempt New Test
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Attempt New Test - Checking signal cables and terminals
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Intermittent fault
Control module communication. Intermittent fault
Checking wiring and terminals
Check the control modules connectors for:
- loose connections according to
Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.
- contact resistance and oxidation according to
Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.
Check the cable between transmission control module (TCM) terminal #14 and engine control module (ECM) terminal #57 and cable between transmission control module (TCM) terminal #27 and engine control module (ECM) terminal #27 for:
- intermittent open-circuit according to
Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.
- an intermittent short-circuit to ground according to
Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.
- an intermittent short-circuit to supply voltage according to
Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.
- intermittent short-circuit to each other.
Continue - Fault-tracing information
DONE
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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 the status of the diagnostic trouble code (DTC)
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