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DIESEL PCM, DLC, I/P


Object Number: 52748  Size: FS
Engine Controls Components
DIESEL PCM, GLOW PLUGS, FUSE-RELAY
OBD II Symbol Description Notice
Engine Controls Schematic References
Engine Controls Schematic References
Engine Controls Schematic References
Engine Controls Schematic References
Engine Controls Schematic References
Engine Controls Schematic References
Handling Electrostatic Discharge Sensitive Parts Notice
Handling Electrostatic Discharge Sensitive Parts Notice
Handling Electrostatic Discharge Sensitive Parts Notice
Engine Controls Schematic References
Engine Controls Schematic References
Engine Controls Schematic References
Engine Controls Schematic References
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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.

  1. 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.

  2. 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?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Ignition OFF for 30 seconds.
  2. Ignition ON, Engine OFF.

Is the MIL ON?

--

Go to Step 3

Go to Malfunction Indicator Lamp (MIL) Inoperative

3

Can the Scan Tool communicate with the PCM?

--

Go to Step 4

Go to Step 7

4

With the Scan Tool, command the MIL ON and OFF.

Does the MIL change states when commanded?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Step 5

5

  1. Ignition OFF.
  2. Disconnect the PCM connectors.
  3. Ignition ON.

Is the MIL OFF?

--

Go to Step 6

Go to Step 17

6

With the Scan Tool, check Engine CAL ID.

Is the proper CAL ID present?

--

Go to Step 26

Go to Step 18

7

With a test light to ground, probe the DLC connector (pin 16.)

Is the test light ON?

--

Go to Step 8

Go to Step 19

8

With a test light to B+, probe the DLC connector (pins 4 and 5.)

Is the test light ON for both circuits?

--

Go to Step 9

Go to Step 20

9

Check for proper operation of the cigar lighter.

Does the cigar lighter operate properly?

--

Go to Step 10

Go to Step 21

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?

--

Go to Step 11

Go to Step 22

11

  1. Disconnect the Scan Tool.
  2. With the J 39200 connected to ground, check the PCM serial data line at the DLC connector (pin 2).

Is voltage on the serial data line less than the specified value?

7 V

Go to Step 12

Go to Step 15

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

Go to Step 13

Go to Step 16

13

  1. Ignition OFF.
  2. With the J 39200 connected to ground, check resistance of the serial data line at the DLC connector (pin 2).

Is resistance less than the specified value?

10 Ohms

Go to Step 14

Go to Step 25

14

  1. Disconnect the PCM connectors.
  2. With the J 39200 connected to ground, check resistance of the serial data line at the DLC connector (pin 2).

Is resistance less than the specified value?

10 Ohms

Go to Step 23

Go to Step 26

15

  1. Ignition OFF.
  2. Disconnect the PCM connectors.
  3. Ignition ON
  4. Check voltage on the DLC connector (pin 2).

Is voltage at the specified value?

0 V

Go to Step 26

Go to Step 24

16

Reprogram the EEPROM and retest. Refer to Powertrain Control Module Replacement/Programming

Is serial data present?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

Go to Step 26

17

Repair short to ground in the MIL control circuit.

Is action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

18

Reprogram the EEPROM and retest. Refer to Powertrain Control Module Replacement/Programming

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

19

  1. Check fuse number 7.
  2. If fuse is blown, repair short to ground in the battery feed circuit to the DLC connector (pin 16.)
  3. If the fuse is OK, repair open in the battery feed circuit to the DLC connector (pin 16.)

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

20

Repair open in circuit that did not light the test light.

Refer to Electrical Diagnosis for ground distribution.

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

21

Repair the cigar lighter.

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

22

Repair or replace the malfunctioning Scan Tool and/or cable.

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

23

Repair short to ground in the serial data line.

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

24

Repair short to voltage in the serial data line.

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

25

  1. Check serial data line for an open.
  2. If OK, check PCM and DLC connections.
  3. If OK, replace the PCM.

The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--

26

Replace the PCM. The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming

Is the action complete?

--

Go to Powertrain On Board Diagnostic (OBD) System Check

--