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DIESEL PCM, DLC, I/P
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Circuit Description
There should always be a steady Malfunction Indicator Lamp (MIL) when the ignition is ON and engine OFF. Battery ignition voltage is supplied to the lamp. The PCM will turn the lamp ON by grounding the ignition feed circuit.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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Check that the Scan Tool is functioning properly on another vehicle. If the scan is functioning properly, and CKT the serial data circuit is OK, the PCM may be at fault for the NO DLC symptom.
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If the light goes OFF when the PCM connector is disconnected, then the control circuit is not shorted to ground.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing DTC(s) use the Scan Tool Capture Info to record freeze frame and failure records for reference, as data will be lost when Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Is the MIL ON? | -- | ||
Can the Scan Tool communicate with the PCM? | -- | |||
4 | With the Scan Tool, command the MIL ON and OFF. Does the MIL change states when commanded? | -- | ||
Is the MIL OFF? | -- | |||
6 | With the Scan Tool, check Engine CAL ID. Is the proper CAL ID present? | -- | ||
7 | With a test light to ground, probe the DLC connector (pin 16.) Is the test light ON? | -- | ||
8 | With a test light to B+, probe the DLC connector (pins 4 and 5.) Is the test light ON for both circuits? | -- | ||
9 | Check for proper operation of the cigar lighter. Does the cigar lighter operate properly? | -- | ||
10 | Verify proper operation of the Scan Tool with a known good vehicle with the same equipment/controller. Does the Scan Tool communicate with known good vehicle? | -- | ||
11 |
Is voltage on the serial data line less than the specified value? | 7 V | ||
12 | With the J 39200 connected to ground, again check the PCM serial data line at the DLC connector (pin 2). Is voltage on the serial data line less than the specified value? | 1 V | ||
13 |
Is resistance less than the specified value? | 10 Ohms | ||
14 |
Is resistance less than the specified value? | 10 Ohms | ||
15 |
Is voltage at the specified value? | 0 V | ||
16 | Reprogram the EEPROM and retest. Refer to Powertrain Control Module Replacement/Programming Is serial data present? | -- | ||
17 | Repair short to ground in the MIL control circuit. Is action complete? | -- | -- | |
18 | Reprogram the EEPROM and retest. Refer to Powertrain Control Module Replacement/Programming Is the action complete? | -- | -- | |
19 |
Is the action complete? | -- | -- | |
20 | Repair open in circuit that did not light the test light. Refer to Electrical Diagnosis for ground distribution. Is the action complete? | -- | -- | |
21 | Repair the cigar lighter. Is the action complete? | -- | -- | |
22 | Repair or replace the malfunctioning Scan Tool and/or cable. Is the action complete? | -- | -- | |
23 | Repair short to ground in the serial data line. Is the action complete? | -- | -- | |
24 | Repair short to voltage in the serial data line. Is the action complete? | -- | -- | |
25 |
The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming Is the action complete? | -- | -- | |
26 | Replace the PCM. The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming Is the action complete? | -- | -- |
