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Nissan Altima: Trouble codes P1122 and P1128

Updated on February 18, 2018

Nissan Altima Trouble Codes P1122 and P1128

We were presented with a Nissan Altima whose throttle didn't respond. It showed trouble codes P1122 and P1128. If you look them up, trouble code P1122 is an Electric Throttle Control Function code, and the P1128 is a Throttle Control Motor (TCM) code.

We were certain that the codes plus some simple diagnostic procedures would send us to the culprit. But, after being in the automotive industry for more than 25 years, we know that things are not always as they seem. The codes P1122 and P1128 are just a starting point, it will be up to the tech to find out the actual cause of the code being set.

When the customer went to Autozone and had the codes read, they suggested that it was the throttle control actuator, so the customer decided to order the part from the Nissan Dealership and install it himself. Needless to say, this did not fix his vehicle. Read on to learn what we found and how we repaired this Nissan Altima.

Here is a list of the first test procedures that were performed on this Altima.

Nissan Altima Throttle Actuator plug

What We Checked in This Diagnostic Procedure

1. Ground screws

  • Switch off ignition.
  • Loosen and tighten the body screws.

2. Motor relay signal circuit I

  • Between ground and ECM terminal 3, check the voltage as given:

Ignition switch off: 0V

Ignition switch on: 11 – 14V

  • If OK: proceed to 10, if no good: proceed to 3

3. Motor relay input signal circuit II

  • Switch off ignition
  • Disconnect the harness connector to the ECM
  • Disconnect the harness connector E 14 of IPDM E/R.
  • Between ECM terminal 3 and IPDM E/R terminal 28:-harness continuity. Continuity should be there.

Harness for short to ground / power.

4. Part that is malfunctioning

  • Harness connectors E50, F1.
  • Harness connector E14 of IPDM E/R.
  • Harness for open/short between ECM and IPDM E/R

Repair open / short to ground / power in harness / connectors.

5. Motor relay power supply circuit I

  • Connect all the harness connectors.
  • Switch off ignition
  • Between ground and ECM terminal 104 check the voltage.(battery).

6. Motor relay power supply circuit.

  • Disconnect the harness connector to the ECM.
  • Disconnect the harness connector E17 of IPDM E/R
  • Between ECM terminal 104 and IPDM E/R terminal 70 check for continuity (there should be continuity).
  • Harness for short to ground / power.

If OK: proceed to 8. If no good: proceed to 7

7. Find the malfunctioning part. Check:

  • IPDM E/R harness connector E17.
  • Between ECM and IPDM E/R harness for open/short.
  • Repair open / short to ground / power in harness / connectors.

8. Fuse

  • Disconnect the fuse (20A)
  • Check for a blown fuse

If OK: proceed to 9. If no good: replace the fuse

9. Intermittent incident

Refer to Trouble Diagnosis for Intermittent Incident

If OK: replace IPDM E/R. If no good: repair/replace harness/connectors.

10. For open / short in motor output signal circuit

  • Switch off ignition.
  • Disconnect the harness connector to the actuator.
  • Disconnect the harness connector to the ECM.
  • Check for harness continuity between terminals

ACTUATOR TER ECM TER CONTINUITY

3 5 no

4 yes

6 5 yes

4 no

Harness for short to ground / power.

If OK: proceed to 11. If no good: repair / replace.

11. Visually inspect actuator.

  • Take the intake air duct out
  • Look for dirt grease etc. in the valve and housing.

If OK: proceed to 12. If no good: clean the inside of the actuator.

12. Inspect motor

If OK: proceed to 13. If no good: proceed to 14

13. Intermittent Incident

Refer to Trouble Diagnosis for Intermittent Incident.

14. Replace the Actuator

End of Inspection

Component Inspection

Disconnect the harness connector to the actuator.

Between terminals 3 & 6 check the resistance: approx: 1 – 15 O at 25°C or 77°F

If no good: replace and proceed to next step.

Remember that the customer already replaced the throttle control actuator himself, in hopes of a simple fix. But we still have to follow the diagnostic procedures in order for us to be as thorough as possible.

Nissan Altima Trouble codes P1122 and P1128

Ok, lets do a quick recap:

VEHICLE: 2002 Nissan Altima SE 3.5L, V6, MFI, DOHC, VIN -, Eng Desg VQ35DE, 3498 CC

MILEAGE: 218168

Customer Concern: Throttle doesn't respond. Trouble codes P1122 and P1128 present. Replaced the throttle control actuator.

After performing the standard diagnostic tests above, one of my techs decided to go a different route. This is the test he performed.

Tests:

1. Check the resistance of the throttle control motor. Specification is 1 to 15 ohms at 77 degrees °F (a known good resistance value is around 8 ohms).

2. Check the circuit between the Electronic Control Module (ECM) and the throttle control motor. Disconnect the throttle control motor and the ECM. Wire a headlight bulb to the Blue/Black and Blue/White wires at the throttle control motor connector. Locate pins 5 (Blue/Black) and 4 (Blue/White) at the ECM connector then apply battery voltage to one wire and a ground on the other. Check the headlight bulb. The headlight bulb will flow about 4 amps through the circuit. If the bulb lights and is bright, wiggle test the harness.

3. Voltage drop the powers and grounds at the ECM. Also voltage drop the Orange wire at pin 3 of the ECM connector (everything connected and backprobing).

Potential Causes:

(A) Electronic Control Module (ECM)

(B) Throttle Motor Control Relay

(C) Wiring is corroded

Confirmed Fix: Repaired Engine Control Module (ECM) Ground(s)

Tech Tips: Trouble code P1128 is set when the ECM detects a shorted throttle control motor circuit or the throttle control motor is shorted. The P1122 is typically set when the throttle control function does not operate properly. It is common to see the throttle control motor supply voltage low due to a poor throttle motor relay. The ECM receives this voltage from the relay and distributes it to the throttle motor.


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    • profile image

      robert 5 years ago

      i learned something new today.

    • hardlymoving profile image

      hardlymoving 7 years ago from Memphis, TN

      Unbelievable. Finding an electrical short is such a pain.

    • earnestshub profile image

      earnestshub 7 years ago from Melbourne Australia

      Very useful data. No matter how good your analyser is, you still can't beat having that 25 years of experience.

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