GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1996 🢒 DeVille 🢒 Engine 🢒 Engine Controls - 4.0L and 4.6L 🢒 DTC P1320 IC 4X Reference Circuit Intermittent

Object Number: 13012 Size: LF
Engine Controls Components
Ignition Control (IC) Module
OBD II Symbol Description Notice
ESD Notice

Circuit Description

The Ignition Control Module creates a 4X signal and a 24X signal that is used by the PCM for ignition and fuel control. If the PCM does not receive 4X reference pulses from the Ignition Control Module for more than 0.4 second while the engine is running, DTC P1320 is set.

Conditions for Setting the DTC

Test Conditions

    •  DTCs P0232 and P1376 are not set.
    •  Engine speed greater than 568 RPM.

Failure Condition

No 4X reference pulse has been received by the PCM for 0.4 second.

Action Taken When the DTC Sets

    •  The Malfunction Indicator Lamp (MIL) will not illuminate.
    •  No message will be displayed.

Conditions for Clearing the DTC

    •  A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
    •  A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
    • Use a scan tool to clear DTCs.
    • Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

Diagnostic Aids
    •  This DTC may set due to a false start condition in which cranking engine exceeds 568 RPM but does not start.
    •  If no fault present check for intermittent opens/shorts in CKT's 430, 539 and 450 or EMI interference on CKT 430.
    •  Without 4X reference pulses the vehicle will start although crank time can be extended to as much as 45 seconds. If this DTC is set with a No Start complaint crank the vehicle for 45 seconds before attempting to determine the cause of a No Start condition.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

  1. Check to see if other ignition DTCs are set.

    2.

  2. Checking for power to the ignition control module.

    3.

  3. Checking if fault is in circuit.

    4.

  4. Checking if fault is in circuit.

    5.

  5. Checking if fault is in circuit.

    6.

  6. IC module output should be 4.2 volts or more.

    7.

  7. A diagnostic jumper can be created with the terminals supplied in the J 38125-A Terminal Repair Kit. Assemble the jumpers and terminals and cover the exposed terminals with heat shrink tubing. Do not cover the spade of the male terminals.

    IC module frequency output should be 30 Hz or more.

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to A Powertrain On Board Diagnostic (OBD) System Check

2

Are DTC's P0232, P0322, P1323 or P1375 also set?

--

Go to DTC's that are set

Go to Step 3

3

  1. Disconnect IC module connector C3.
  2. Turn the key ON.
  3. Using DMM J 39200 measure the voltage to ground at C3 terminal C (harness side).

Is the voltage the same or more than the value specified?

10.0 volts

Go to Step 4

Go to Step 10

4

  1. Record the fluid life indexes, turn the key to LOCK and wait 30 seconds.
  2. Reconnect IC module connector C3.
  3. Disconnect IC module connector C4.
  4. Disconnect PCM connector C2.
  5. Using DMM J 39200 measure the resistance to ground at PCM connector C2 terminal 44.

Is the resistance more than the value specified?

10K ohms

Go to Step 5

Go to Step 11

5

Measure the resistance between IC module connector C4 terminal C and PCM connector C2 terminal 44.

Is the resistance the same or less than the value specified?

5 ohms

Go to Step 6

Go to Step 12

6

  1. Turn the key ON.
  2. With IC module connector C4 disconnected measure the voltage to ground at PCM connector C2 terminal 44.

Is the voltage less than the value specified?

0.5 volts

Go to Step 7

Go to Step 13

7

  1. Reconnect IC module connector C4.
  2. Measure the voltage to ground at PCM connector C2 terminal 44.

Is the voltage more than the value specified?

4.2 volts

Go to Step 8

Go to Step 14

8

  1. Turn the key to LOCK.
  2. Reconnect PCM connector C2.
  3. Disconnect IC module connector C4.
  4. Install diagnostic jumper.

    5. OR:

    • Jumper C4 terminal A to module pin A.
    • Jumper C4 terminal B to module pin B.
    • Jumper C4 terminal C to module pin C.
    • Jumper C4 terminal D to module pin D.
    • Jumper C4 terminal E to module pin E.
    • Jumper C4 terminal F to module pin F.
  5. Set the DMM to 400 mV A/C scale and push the Hz button.
  6. Start the engine, refer to Diagnostic Aids.
  7. Connect the DMM between jumper C and ground.

Does the FREQUENCY measure less than the value specified?

30 Hertz

Go to Step 14

Go to Step 9

9
  1. Remove all jumpers.
  2. Reconnect IC module connector C4.
  3. Clear the DTC.
  4. Start and idle engine.
  5. On the scan tool select DTC Info then Fail This Ign.

Has DTC P1320 reset?

--

Go to Step 16

Fault not present. Refer to Diagnostic Aids

10
  1. Repair cause of no voltage to the IC module.
  2. Possible causes are:
    3. • Short in the Ignition Feed circuit to the (IC) module (blown fuse).
    • Open in the Ignition Feed circuit to the (IC) module.
    • Shorted IC module (blown fuse).

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

11

Repair the short to ground in the Fuel Control (4X) circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

12

Repair the open in the Fuel Control (4X) circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

13

Repair the short to voltage in the Fuel Control (4X) circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

14
  1. Check terminal contact at the IC module connector C4 terminal C.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 15

15

Replace the Ignition Control Module. Refer to Ignition Control Module Replacement (Assembly) .

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

16
  1. Check terminal contact at the PCM connector C2 terminal 44.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 17

17

Replace the PCM. Refer to PCM Replacement/Programming .

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--