U1118 Lost engine message

U1118 code - The transmission control module (TCM) receives information from the engine, antilock brake system, and the electronic gear shift control modules over the Can C bus. The Can C bus is a high speed communication bus that allows real time control capability between various controllers. Most messages are sent 20 msec, this means critical information can be shared between multiple controllers almost instantaneously. The Can C bus is a two wire bus with a CAN (+) and a CAN (-) circuit. To reduce the potential of radio and other electrical noise interference, the Can Bus circuit wiring is manufactured using a twisted pair configuration within the electrical wiring harness.

The DTC will set if a valid Can Id was not received in the required time from the ECM/PCM.

Possible causes U1118 code:

- Transmission Control Module (TCM)

Diagnostic test U1118 code

Step 1. Check the TIPM for TIPM DTCs.

Does the TIPM report the DTC U0001 Can Bus or U0100 Lost Communication with ECM/PCM ?

Yes, perform NAG1 Transmission Verification Test.

No, go to step 2.

Step 2. Check If the DTC is current 

Note : When the transmission control module (TCM) detect and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set. This information is located in the scan tool under environmental data. Before erasing any stored DTCs, record any available data to assist in duplicating the conditions in which the DTC originally set.

Ignition on, engine not running. With the scan tool, erase transmission DTCs. Using the environmental data recorded earlier, try to duplicate the conditions in which the DTC originally set. It may be necessary to test drive the vehicle. With the scan tool, read transmission DTCs.

Did the DTC U1118 Lost engine message reset ?

Yes, using the schematics as a guide, check the transmission conrtrol module (TCM) twrminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM in accordance with the service information. Perform NAG1 Transmission Verification Test.

No, go to step 3.

Step 3. Check the wiring and connectors 

The conditions necessary to set this DTC are not present at this time. Uising the schematics as a guide, inspect the wiring connectors specific to this circuit. Wiggle the wiring and connectors while checking for any possible open or shorted circuits. Check for any service information tune-ups or technical service bulletins that may apply.

Were there any problem found ?

Yes, repair as necessary. Perform the NAG1 transmission verification test. Refer to 28 DTC based diagnostics/module, transmission control (TCM) standard procedure.

No, test complete.

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