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Non repairable/difficult to repair auto faults

Non repairable/difficult to repair auto faults image
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The Nigeria automotive market is such that is dominated by sales of foreign used vehicles, no thanks to the expensive nature of brand new vehicles or not readily available credit facility for such purchase. Vehicle being a necessity, most aspiring vehicle owners have resorted to the foreign fairly used vehicles. Many of the vehicles give a good value for money, thanks to a relatively good vehicle maintenance culture and also mandatory periodic and effective vehicle maintenance inspection in most of the countries where the vehicle comes from.

These however do not apply generally to all vehicles. All these vehicles come with one or more damage histories. Some are without issues, some could have different issues such as salvage accidental/flood, engine issue, transmission issue, and a host of others problems. Careful observation needs to be made prior to purchasing a vehicle. One of such considerations is to try knowing the type of defect on such vehicles.

Vehicle defect can be categorised into two types; non repairable/difficult to repair and repairable defects

Non repairable/ difficult to repair defect: This  defect happens to some parts on the vehicle that are difficult to repair, such defects could lead to other issues such as drivability and stability issues.

Examples of non-repairable defects are: (A)Impacts that have affected the vehicle chassis/frame: the vehicle chassis/frame is the undercarriage of the vehicle on which other parts are mounted. It gives the structurer support to the vehicle.  A defect on this part alters the vehicle’s structure and its effect could cause irregular tyre wear, suspension and drivability are some  of the issues. (B)Flooded vehicle: A flooded vehicle is regarded as a vehicle that has a heavy intrusion of water due to heavy flooding. Water being an electrolyte could easily short circuit electrical circuits as well as damage electronic components and also induce corrosion on the wiring system of a vehicle. A flooded vehicle would have a lot of electrical malfunction and this starts to show up after some month of purchase. From experience, it is always a difficult task repairing such a vehicle. One issue would always lead to another one. (C) Rust: Vehicles that come from some areas are known to have rusted due to the salty nature of their water. This eats deep into the metal and makes it brittle and easy to break. The extent of rust could be unimaginable on some vehicles and these need to be determined before such a vehicle is bought.

This piece is written by my mentee Ibrahim Ogundele

Generic codes

P1121: Electric throttle control actuator (adsbygoogle = window.adsbygoogle || []).push({});

Meaning

Electric throttle control actuator consists of throttle control motor, throttle position sensor, etc. The throttle control motor is operated by the engine control module and it opens and closes the throttle valve.

The throttle position sensor detects the throttle valve position, and the opening and closing speed of the throttle valve and feeds the voltage signals to the ECM. The ECM judges the current opening angle of the throttle valve from these signals and the ECM controls the throttle control motor to make the throttle valve opening angle properly in response to driving condition.

Possible symptoms

  • Engine light ON (or service engine soon warning light)
  • No throttle pedal response

Possible causes

  • Faulty electric throttle control actuator
  • Electric throttle control actuator harness is open or shorted
  • Electric throttle control
  • Actuator circuit poor electrical connection

P1122: Throttle position sensor circuit intermittent low voltage

Meaning

Electric throttle control actuator consists of throttle control motor, throttle position sensor etc. The throttle control motor is operated by the engine control module and it opens and closes the throttle valve.

The throttle position sensor detects the throttle valve position, and the opening and closing speed of the throttle valve and feeds the voltage signals to the ECM. The ECM judges the current opening angle of the throttle valve from these signals and the ECM controls the throttle control motor to make the throttle valve opening angle properly in response to driving condition.

Possible causes

  • Faulty electric throttle control actuator
  • Electric throttle control actuator harness is open or shorted
  • Electric throttle control actuator circuit poor electrical connection

P1123: Throttle position sensor circuit intermittent high voltage

Meaning

The powertrain control module monitors the throttle position sensor. The PCM sets the diagnostic trouble code when it detects the throttle position sensor circuit is intermittent high voltage.

Possible causes

  • Faulty throttle position sensor
  • Throttle position sensor harness is open or shorted
  • Throttle position sensor circuit poor electrical connection
  • Faulty powertrain control module

P1124: Throttle control motor relay circuit short

Meaning

Power supply for the throttle control motor is provided to the Engine Control Module via throttle control motor relay. The throttle control motor relay is ON/OFF controlled by the ECM. When the ignition switch is turned ON, the ECM sends an ON signal to the throttle control motor relay and battery voltage is provided to the ECM. When the ignition switch is turned OFF, the ECM sends an OFF signal to the throttle control motor relay and battery voltage is not provided to the ECM.

Possible causes

  • Faulty throttle control motor relay
  • Throttle control motor relay harness is open or shorted
  • Throttle control motor relay circuit poor electrical connection

P1125: Throttle position sensor intermittent

Meaning

The accelerator pedal position sensor 1 and the APP sensor 2 are potentiometer type sensors, each with the following circuits:

  • A 5-volt reference circuit
  • A low reference circuit
  • A signal circuit

The control module provides the APP sensors with a 5-volt reference circuit and a low reference circuit. The APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed.

The APP sensor 2 signal voltage is low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 and the APP sensor 2 signal circuits are out of correlation with each other, DTC P1125 sets.

Possible causes

  • Faulty accelerator pedal position sensor
  • Accelerator pedal position sensor harness is open or shorted
  • Accelerator pedal position sensor circuit poor electrical connection

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