Circuit Description
The Door Control Module (DCM) Diagnostic Check is an organized approach to identify problems associated with the DCM. This check must be the starting point for any DCM complaint, and will direct you to the next logical step in diagnosing the complaint. The DCM is a very reliable component and is not likely the cause of the malfunction. Most system complaints are linked to faulty wiring and connectors, and occasionally to components. Understanding the computer system and using the tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.
Diagnostic Aids
| • | The following conditions may result in an intermittent operation of the DCM with no DTC stored: |
| - | Any condition which results in the interruption of power to the DCM |
| - | Out of range battery or ignition voltage |
Specification
Normal DCM operating voltage: 9.0-16.0 V
| - | A loose or damaged ground(s) |
| - | An open or shorted serial data line |
| • | An intermittent failure in the electronic system may be very difficult to detect and to accurately diagnose. The DCM test for different malfunctions under different vehicle conditions. For this reason, a thorough test drive is often needed in order to repeat a malfunction. If the system malfunction is not repeated during the test drive, a good description of the complaint may be very useful in locating an intermittent malfunction. Faulty electrical connections or wiring causes most intermitting problems. When an intermitting condition is suspected, check the suspected circuits for the following conditions: |
| - | Poor mating of connector halves or backed out terminals |
| - | Improperly formed or damaged terminals |
| - | Wire chafing |
| - | Poor wire to terminal connections |
| - | Dirty or corroded terminals |
| - | Damage to connector bodies |
| • | The DCM has the ability to store DTCs as history codes only. Therefore, when a DTC is stored , the DCMs will display all DTCs as history even thought the malfunction is current. Always diagnose history DTCs the same way as current DTCs by performing the applicable DTC table. |
| • | If the problem is intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Perform a thorough inspection of all related wiring and connectors pertaining to the history DTC stored. Refer to Intermittents and Poor Connections . |
| • | Exit all scan tool tests before cycling the ignition OFF to ON unless the scan tool instructions direct otherwise. Follow the operating instructions in the scan tool operator's manual. Failure to follow these instruction may set DTCs, cause vehicle system malfunctions, set false DTCs, or cause scan tool malfunctions. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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Tests if the LH and RH DCMs are able to communicate. Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
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The presence of any DTC stored in the LH and RH DCM.
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The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
Step | Action | Yes | No |
|---|---|---|---|
1 | Install a scan tool. Does the scan tool power up? | Go to Step 2 | |
Does the scan tool communicate with both DCMs? | Go to Step 3 | ||
Select the LH DCM and RH DCM display DTCs function on the scan tool. Does the scan tool display any DTCs in the LH DCM or RH DCM? | Go to Step 4 | Go to the Applicable Symptom Table | |
Does the scan tool display any DTCs which begin with a "U"? |
