P1923
Read the instructions below then
start the fault diagnostic procedure.
Symptom: Some of the following symptoms may be observed:
Engine will not start.
CHECK ENGINE.
Automatic transmission does not change gear.
CHECK GEARBOX.
Further diagnostic trouble codes in Trionic (P1624 or P1908).
Diagnostic trouble code P1921 or P1902 in TCM (if TCM can be contacted).
No Bus Data From TCM. See Fault Tracing 3:5 Bus and Diagnostic Communication.
Fault symptoms
Some of the following symptoms may be observed:
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Automatic transmission does not change gear.
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Further diagnostic trouble codes in Trionic (P1624 or P1908).
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Diagnostic trouble code P1921 or P1902 in TCM (if TCM can be contacted).
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On-Board Diagnostics
Type of diagnosis:
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Continuous. However, it is interrupted once the fault criteria have been fulfilled and does not restart until the next driving cycle.
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Enable criteria:
(Conditions that must be fulfilled for diagnostics to be performed.)
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Engine running. TCM has previously been on the bus on some occasion.
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Fault criteria:
(When enable criteria have been fulfilled, diagnostics will check if the fault criteria have been fulfilled.)
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No communication for more than 3s.
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Dependents:
(Once fault criteria have been fulfilled, a number of other diagnostics must report OK before the diagnostic trouble code can finally be generated.)
System reaction to a fault:
(Once the fault criteria have been fulfilled, certain measures will sometimes be taken.)
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Max. engine torque (Bus from TCM) is set to 310 Nm.
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OK report:
(This diagnosis may be included as a dependent to another diagnosis and must therefore report OK even if it is continuous. The OK report is also used in fault handling to count down the fault counter.)
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Enable criteria fulfilled and fault criteria not fulfilled within 60s.
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Fault handling:
(Refer to section “Fault diagnosis, general” for more information.)
Diagnostic help
Fault diagnosis concerns an intermittent electrical fault in the power supply to the sending control module or on one of the bus leads.
Check the wiring
Jiggle the wiring harness at several points and in different directions to check if there are intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic instrument during the test.
